STUDIES IN GASTRIC SECRETION

IV. VARIATIONS IN THE CHLORINE CONTENT OF GASTRIC JUICE AND THEIR SIGNIFICANCE*

BY FRANKLIN HOLLANDERt

(From the Department of Physiology, New York Homeopathic Medical College, New York, and the Biological Laboratory,

Cold Spring Harbor, New York)

(Received for publication, April 21, 1932)

INTRODUCTION

The present investigation is a study of the variations in the concentrations of both total and neutral chloride of gastric juice, obtained from Pavlov pouch dogs by stimulation with either food or histamine. It differs from all such studies previously reported in that an attempt is here made to correlate these con- centrations with the acidity of the secretion, instead of with its rate of flow or with the time interval between stimulation and collection of the secretion. This problem of the chlorine content of gastric juice derives its importance from two major sources: first and foremost, its bearing on the question of the source of the neutral chloride occurring in gastric juice; and second, its signifi- cance for an understanding of the mechanism of formation of hydro- chloric acid. Because of its importance in these respects and also because of the failure of previous investigators to establish any significant regularity in connection with the problem, this reexami- nation of the nature and causes of variations in the concentration of gastric juice chlorides was undertaken.

A survey of the work published by numerous other investigators

* A preliminary report of this work was presented in the Proc. Sot. Exp. Biol. and Med., 29,640 (1932).

t The author wishes to express his indebtedness to Samuel Galburt, Gerson Hollander, and Eva Saper for their assistance at various stages of this investigation.

585

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586 Studies in Gastric Secretion. IV

of this subject fails to reveal any unanimity of opinion regarding it. Some of the workers with pure gastric juice have maintained that, even in the presence of wide variations in total acidity, the total concentration of chloride remains constant (Rosemann, 1907, 1911; Frouin and Gerard, 1912; Cohen, 1920; MacLean, Griffiths, and Williams, 1928; Bulger, Allen, and Harrison, 1928). In some of these papers the variation is small, whereas in others it is considerable; e.g., Cohen reports twenty-three chlorine values lying between 0.39 per cent and 0.54 per cent-a range equivalent to more than 30 per cent of ,the mean value. In contrast with these observers, others (Delhougne, 1926; Bliss, 1930) have recognized the exist’ence of major variations in the chloride concentration, but these were always less than the corresponding variations in acidity. That these relatively small fluctuations may not be accidental but have a real significance is suggested by the further observations of Bliss that, following gastric stimulation the total chloride concentration rises to a maximum and then decreases, and that the curves for chloride and acid secretion are at least qualitatively parallel.

A similar parallelism of chloride and acidity values is observable in the results of numerous clinical investigators, following stimula- tion either by mechanical means or by test meal (Girardi and Cipriani, 1925; Polland, Roberts, and Bloomfield, 1928; Steinitz, 1928; Bliss, 1930). Another group of workers with human sub- jects (Pfaundler, 1900; Katsch and Kalk, 1926; Mirkin, Mogi- lewsky, and Rabinowitsch, 1927; Gorham, Stroud, and Huffman, 1928) have noted the occurrence of unmistakable variations in chloride content which, however, bore no relation to fluctuations in acidity. Most of these reports indicate that such irregular variations occur within far narrower limits than obtain for the corresponding acidity values. Finally, there have been a number of publications (MacLean and Griffiths, 1928; Bulger, Stroud, and Heideman, 1928; Rudd, 1930) in which it is maintained that the total chlorine concentration of stomach contents is approximately constant, even though the acidity manifest the usual changes.

Regarding variations in the concentration of neutral chloride (or fixed base, since anions other than chloride are virtually absent from gastric juice), several different views are current at present. Numerous investigators have shown that there exists a reciprocal

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relation between t.he concentration of neutral chloride and the total acidity, whereby the one increases as the other decreases (Pfaundler, 1900; MacLean, Griffiths, and Williams, 1928; Bulger, Stroud, and Heideman, 1928; Close, 1929). More recently, it has been suggested that the neutral chloride-time curve is parallel to the corresponding pepsin activity-time curve (MacLean, Griffiths, and Hughes, 1929; Gilman and Cowgill, 1931). As yet, however, there has been no evidence to indicate the significance of these findings, or that either of these relations is a quanti- tative one.

In the present contribution it will be shown that for pure gastric juice (i.e. uncontaminated by food, saliva, regurgitated duodenal contents, and particularly blood and exudates arising from trauma) there exists a very simple mathematical relation between both the total and neutral chloride concentrations on one hand and the total acidity on the other. These relations are such as to be en- tirely in agreement with the views advanced in previous papers of this series concerning the nature of the parietal secretion and the process by which the usual extensive variations in stomach pouch acidity are brought about. Thus, the evidence will be shown to support a view regarding the several sources of the chlo- ride radical in gastric juice which is part of a consistent picture of some of the processes involved in gastric secretion.

Methods

The following observations were made on five dogs, provided with fundic pouches of the Pavlov type. Some of the data were gotten by means of the continuous colleclion technique generally employed in such work; others were obtained by the discontinuous collection method, which depends on the retention of the gastric juice by a sphincter at the mouth of the pouch. The details of both these procedures, as well as the preparation and care of the animals, have already been described (Hollander and Cowgill, 1931). In conformity with the usual practice in this laboratory, every possible precaution was taken to prevent admixture with the gastric juice of blood or exudate, particularly any that might arise from abrasion of the mucosa.’ The great importance of

* As a measure of the extent to which this high standard of technique was attained, it may be mentioned here that several samples of mucus-free juice

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Studies in Gastric Secretion. IV

extreme caution in this respect cannot be emphasized too strongly if results possessing any reliable quantitative significance are to be obtained. In some of the experiments, food was employed as stimulus to secretion; in others, a subcutaneous injection of histamine. When the cliscontinu.ous collection procedure was used, the specific precautions designed to yield “constant acidity juice” were omitted, since it was desired to obtain samples, the acidities of which extend throughout the normal range ordinarily en- countered.

Total acidity determinations were carried out by the micro titration method previously described (Hollander, 1931, a). Total chlorine determinations were performed by the method of Wilson and Ball (1928). Neutral chloride was calculated as the difference between the millimolar concentrations of total chloride and hydrochloric acid. Since the acid and chloride determina- tions are reliable to no better than 0.5 per cent, and the latter may even be as poor as 1.0 per cent, the reliability of the neutral chlo- ride concentration calculated from these is probably no better than 1.5 per cent.

Observations

Total Chloride Concentration

In the first series of experiments, an attempt was made merely to repeat the observations of other investigators under carefully controlled conditions. Nineteen experiments were performed, the continuous collection technique and all five of the dogs being used. Both types of stimulus were employed to induce secretion. Samples were collected at convenient time intervals and acidity and total chloride determinations were made on all of them. The results, in millimolar concentration, were plotted against the times corresponding to the mid-points of the collection intervals. Twelve of these experiments manifested very good evidence for a qualitative parallelism of the acidity and chloride curves, irrespec- tive of the conditions of the individual experiment. A very good example of this relation is shown in Fig. 1 (Experiment B-57),

obtained from one of these dogs showed a complete absence of phosphate when tested by the method of Fiske and Subbarow. The further signifi- cance of this observation will be discussed in the next paper of this series.

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in which it can be seen that, with but one exception (associated with a period of vomiting), every rise or fall in acidity is accom- panied by a like change in chloride concentration. In all the experiments, however, the total range of variation for chloride was very much less than that for acidity.

In the seven experiments in which this parallel relation between acid and chloride concentrations was not so apparent, masking of the parallelism may be accounted for in the following way. The experimental errors in the analytical methods, as we have already indicated, are relatively large; in the case of the neutral chloride values, this error may be 2 millimols or more. Also, in addition

170 170

l,o-~ .io

150- B

-1WE

q140- TOTAL ACID -1403

3130- 130

; 120- /--‘ii!

110 -

100 90 so

1 2 3 4 5 6

I;=

TIME IN HOURS % mM TOTAL ACID

Fro. 1 FIQ. 2

FIQ. 1. Total chloride and acidity as functions of time; Experiment B-571 FIG. 2. Total chloride as a function of acidity; Experiment B-57.

to the accidental variations which are notoriously inherent in all work with living animals, there are numerous speci& uncontrol- lable factors which obtain in the present work. Among these are the variations in the proportions of mucus, enzyme secretions, and other constituents which may be mixed with the pure parietal secretion; also, changes occur in the osmotic pressure of the blood, arising from the various processes which accompany digestion and secretion, and which exert a wholly unpredictable influence on the total electrolyte concentration of gastric juice throughout any one experiment. Consequently, we are dealing here with a suc- cession of chloride values which differ among themselves by only small amounts, and upon which there is superimposed an aggregate

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590 Studies in Gastric Secretion. IV

of accidental errors of considerable magnitude relative to the range of these chloride values. In the case of the seven experiments which manifested no parallelism, this range was particularly small, and therefore the influence of such random variations might easily be sufficient to change the directions (up or down) of some of the line segments joining the successive chloride points in the graphs. Such a shift in the directions of only a few of the line segments would serve to disrupt entirely the parallelism which is so obvious in a majority of the experiments. It may be concluded, therefore, that our results verify the observations of previous investigators who have reported a qualitative parallelism between the acid and chloride concentrations in gastric juice. At the same time, the large experimental errors serve to explain why so many other workers have reported either variations in chloride values uncorre- lated with acidity, or else an ostensible constancy of this concen- tration factor.

Such a parallelism suggests the existence of an exact quantita- tive relation between chloride and acid concentrations, although such experiments have never been analyzed and studied from this point of view. Therefore, the same data were replotted with the exclusion of time as a variable; i.e., total chloride was plotted directly against total acidity. The result, in each case, was a straight line within reasonably narrow limits. In the illustration in Fig. 2, plotted from the same data as Fig. 1, no point deviates from the line by more than 3 millimols. Further, these deviations are entirely random; i.e., they manifest no systematic trend away from the straight line.

Now, the failure of the individual points to show an even closer approximation to the straight line than they do may be ascribed to these same factors which were discussed above as ordinarily contributing to the accidental errors in these experiments. In order to reduce the influence of these accidental and variable factors, the logical procedure would be to combine the results of a large number of such experiments and subject them to statistical treatment. This method, however, demands such a large body of data that it is made prohibitive by the practical difficulties in- volved in carrying out so many experiments. Accordingly, a highly simplified procedure was employed instead. The chlorine and acid values for the 121 points of all nineteen experiments were

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first arranged in the order of increasing acidity, and independently of the conditions of the original experiments. They were then grouped in such a way that all the chlorine values corresponding to acidities 100 to 109 mM were placed in the first group, acidities 110 to 119 mM in the second, and so on to the seventh group of acidi- ties 160 to 169 mM. When the averages for both acid and chloride values within each group were calculated and the results were plotted (Fig. 3), they yielded zb straight line from which no point deviated by more than about 1.5 mM. This result is all the more striking because it embodies the data of those experiments which showed no parallelism in the first place. It follows, therefore, that an analysis of the combined data of all nineteen experiments by t.his method of averages confirms the conclusion to be drawn from a majority of them when studied individually.

FIG. 3 FIG. 4 FIG. 3. Total chloride as a function of acidity; mean curve for nineteen

continuous collection experiments. FIG. 4. Total chloride as a function of acidity; mean curve for Experi-

ment C-19, a discontinuous collection experiment.

Since the first series, consisting entirely of experiments by the continuous collection technique, gave such striking results, it was next attempted to make a similar analysis of data obtained by the discontinuous collection procedure. Accordingly, in the second series of experiments, three sets of such data were obtained from as many dogs, with various foods as stimuli. In some instances, the samples had been retained in the pouches for 12 or more hours. The data so obtained were then grouped and averaged as before, observations for each animal being treated independently of the others. The resulting graph from one set of such observations, containing a total of twenty-nine samples from Dog R, is shown in Fig. 4. In this particular case, the maximum deviation is only about 0.5 mM. It follows, therefore, that the straight line

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592 Studies in Gastric Secretion. IV

relation between chloride and acid concentrations holds equally well for both methods of collecting gastric juice.

In final corroboration of the existence of this simple mathe- matical relation between the two variables, the same method of analysis with exclusion of the time factor was applied to some data from the work of another investigator. For this purpose a paper was chosen in which it was claimed that the chloride concentra- tion of pouch juice is constant throughout any one experiment. The values from two single experiments on different dogs, reported by MacLean, Griffiths, and Williams (1928) in their Figs. 1 and 2, were used for this purpose. From the resulting graph (Fig. 5), there can be no doubt but that these observations also support

I I I I " do 1:O do 130 140 150 160

m?d TOTAL ACID d TOTAL ACID

FIQ. 5 FIG. 6 FIQ. 5. Total chloride as a function of acidity; data from two experi-

ments by MacLean, Griffiths, and Williams. FIG. 6. Neutral chloride as a function of acidity; Experiment B-57.

the conclusion established by means of our own data. Thus, additional evidence to support the existence of this quantitative relation can be adduced even from the work of other investigators who failed to seek it.

Neutral Chloride Concentration

The evidence so far presented relates only to the total concentra- tion of chlorine in gastric juice. Possibly even more importance, however, attaches to the neutral chloride content; that is, all inorganic chlorides other than hydrochloric acid. It is generally assumed that organic chlorine is virtually absent from the gastric secretion; therefore, the difference between the concentrations of

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total chloride and acid is usually taken as equal to the neutral chloride concentration. Since no serious objection to this assump- tion has ever been advanced, the same procedure has been em- ployed in the present work. In each of Figs. 6, 7, and 8 there will be found a graph of the total acidity plotted against the concentra- tion of neutral chloride, calculated from the data of the correspond- ing figures (Figs. 2 to 4, respectively). As might be anticipated from the nature of the total chloride plots, the data in all three cases fit straight lines extremely well. Although it has been pointed out repeatedly by other investigators that the neutral chloride concentration increases as the acidity decreases, it has never before been shown that the relation is so precise a one as

110 120 130 140 150 160 mN TOTAL ACID mM TOTAL ACID

FIG. 7 FIG. 8 FIG. 7. Neutral chloride as a function of acidity; mean curve for nineteen

continuous collection experiments. FIG. 8. Neutral chloride as a function of acidity; mean curve for Experi-

ment C-19, a discontinuous collection experiment.

this. Thus it may be concluded that the neutral chloride con- centration, as well as the total chloride concentration, is linked to the acidity according to a straight line relation.

It is probable that the physiological connection between these three variables is correspondingly simple, and that some indication of its nature can be discovered from the characteristics of these mathematical relations. Chief among these characteristics are the following: (1) For both total and neutral chloride concentra- tions, the graphs are straight lines. (2) These lines are not hori- zontal but make angles with the acidity axis which are fairly uniform for all the cases examined. These angles are given in Columns 3 and 5 of Table I, under the headings CQ and “noi. The

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594 Studies in Gastric Secretion. IV

measured values for the tangents of these angles, which represent the slopes of the lines, are given by rnoi and ??&gCl in Columns 4 and 6. (3) In Column 7 under the heading IA, there are listed the intercepts of the neutral chloride lines with the acidity axis. For all the diverse cases here examined, these acidity values vary from 163 to 173 mM, which involves an extreme variation of only &3 per cent from the mean value of 168.

TABLE I

Characteristics of Straight Line Relalions between Total Chloride, Neutral Chloride, and Total Acidity

%l = the angle which the total chloride graph makes with the hori- zontal axis; aBCl = the angle which the neutral chloride graph makes with the horizontal axis; mQ = tan aC.; mBC, = tan agC1; IA = the intercept of the neutral chloride graph with the acidity axis.

Experiment

(1)

B-57 (19 experiments) c-19 MacLean c-20 C-25

-

Fig. No.

(2)

296 3,7 4,s 5 * *

- I Vl Yl

(3) (4) ~~

degrcca

10.9 0.19 15.8 0.28 11.2 0.20 9.2 0.16

10.8 0.19 18.4 0.33

OBCI mBCl ‘A

(5) (6) (7) ---

degrees ?nH

128.9 -0.81 168 125.5 -0.72 167 128.8 -0.80 173 130.0 -0.84 163 129.0 -0.81 173 123.8 -0.67 166

* These are the two discontinuous collection experiments, the graphs for which have not been presented here.

DISCUSSION

The chief interest in experiments such as those with which we are dealing here arises from the light which they may throw on the origin of the chloride radical in pure gastric juice. It is generally recognized that one major source of this element is the hydro- chloric acid of the parietal secretion. It is only about the remain- ing portion, the so called neutral chloride, that there has been any extensive controversy.

On this question, investigators are divided into two schools. One of these groups maintains that the non-acid fraction also arises primarily from the parietal cells. The mechanism of acid secretion postulated by these workers involves the initial formation

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F. Hollander

of an isotonic solution of neutral chlorides from the blood, via the lymph and the parietal cytoplasm. These salts are then converted in varying degree to hydrochloric acid, the cation so liberated from the salt being reabsorbed and ultimately returned to the blood stream. Thus, the parietal secretion which enters the lumen of the stomach is an isotonic mixture of hydrochloric acid and neutral chlorides, in which the proportion of the latter decreases as the rate of secretion and the acidity both increase. This conception was first introduced by Rosemann (1907); since that time it has received support from an ever increasing number of investigators of gastric juice chlorides (Delhougne, 1926; Close, 1929; Duth- rie, 1930).

In opposition to this school of opinion we have another which maintains that the neutral chloride of the gastric juice is derived from cells in the gastric mucosa other than the parietal cells. Beginning with Heidenhain and Pavlov, we find the view advanced that the parietal secretion contains a constant concentration of hydrochloric acid, and that all of the commonly observed fluctua- tions in acidity can be traced to the partial neutralization of this fluid by the mucous film which covers the mucosa at the beginning of secretion. In harmony with this conception, it has been main- tained by many (among them Katsch and Kalk, 1926; Gamble and McIver, 1928; Bulger, Stroud, and Heideman, 1928; and McCann, 1929) that the neutral chlorides of the pure gastric juice are derived primarily from the mucous secretion rather than from the parietal secretion.

Recently, the Heidenhain-Pavlov theory was directly confirmed by Hollander and Cowgill (1931) who found that when gastric juice is collected from stomach pouch dogs in such a way as to reduce the mucous secretion to a minimum, the acidity actually is constant. The magnitude of this normal constant acidity was independent of the velocity of secretion, type of stimulus, indi- vidual animal, etc. In fact, evidence of various kinds, including the observations of Gamble and McIver (1928), suggested that it was determined predominantly by the osmotic concentration of the blood at the time of formation of the secretion. In contra- distinction to the original theory, however, these observations indicated that the agent which causes the ordinary fluctuations in acidity of the pouch juice is elaborated continuously during

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Studies in Gastric Secretion. IV

the secretory process, instead of being formed entirely before the beginning of hydrochloric acid secretion, as Pavlov believed. This agent consists of mucous secretion, peptic secretion, epithelial detritus, and possibly a lymph transudate, with the mucus playing by far the most important part.

In order to compare this modification of the Heidenhain-Pavlov theory with the results of t,he present investigation, it is necessary to extend the former still further so that it can be formulated quantitatively. Accordingly, as a preliminary working hypothe- sis, we conceive of gastric pouch juice as being a mixture of (1) the parietal secretion-which is an isotonic solution of hydrochloric acid containing no base and therefore no neutral chloride; and (2) a neutral or alkaline fluid-which is predominantly mucus. In the absence of data on the composition of pure gastric mucus, this fluid is assumed to be a colloidal dispersion of mucin in an isotonic mixture of neutral chlorides and bicarbonates, the con- centration of the latter being smaller than that of the former. Other lymph constituents, like the phosphate radical, are also present, though in very small amounts.

When two such liquids are mixed, the acidity of the parietal secretion will be reduced by neutralization, with the loss of carbon dioxide, and also by dilution. The extent of this reduction will vary with the proportions of the components. Thus, the concen- tration of hydrochloric acid in the mixed gastric juice can possess any value between a maximum, corresponding to pure parietal secretion, and an “acid deficit”, corresponding to the bicarbonate content of the mucous mixture. The total chloride concentration, however, will fluctuate within much narrower limits; the minimum value, fixed by the chloride concentration of the mucus, is not very much less than the maximum value, determined by the pure parietal secretion. The extent of this chloride range is equal to the bicarbonate concentration of the alkaline constituent. Since this is assumed to be less than half the total concentration of base in mucous, it follows that the decrease in total chloride suffered by the parietal fluid on admixture with the other will always be much less than the corresponding diminution in its total acidity value. As for the concentration of base in the mixed gastric juice, its value will fluctuate between zero and a maximum value corre- sponding to the unacidified mucous mixture.

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Let us now examine some of the results of the present investi- gation, in the light of the opposing hypotheses advanced by Rose- mann and by ourselves.

It has been found that, within the limits of error permitted by experimentation of this kind, the relation between total chloride concentration and acidity can be expressed by a straight line which is not parallel to the acidity axis. The occurrence of a straight line relation implies that the several factors which deter- mine these concentrations are quantitative and exact; that is, variations in these concentrations are probably the result of a simple chemical or physiological process. That the line is not parallel with the acidity axis is especially significant, for if it were, it would betoken a constancy of total chloride concentration simultaneous with changes in acidity, such as the Rosemann hypothesis predicates. Fluctuations in the general osmotic equilibrium of the animal, according to this view, might manifest themselves by an increase in the random deviations of the indi- vidual points from the line, or by a vertical displacement of the line in its entirety; the general trend, however, would always conform to a horizontal line. Our hypothesis, on the contrary, implies that a decrease in acidity is always accompanied by a cor- responding decrease in the total chloride concentration. The magnitude of this chloride change must invariably be less than that for the acidity. With these latter implications, the present obser- vations conform completely.2

A second point of agreement between our present view of the secretion process and the facts can be demonstrated in the follow- ing way: according to our hypothesis, the maximum acidity attain- able in gastric juice is that which corresponds to the pure parietal secretion, undiluted and unneutralized; this fluid is characterized by (1) the absence of fixed base, and (2) a concentration of hydro- chloric acid which is isotonic with the blood. On the other hand, the intercept of the experimental neutral chloride graph with the acidity axis, which corresponds to a secreted fluid of zero salt

2 It, may be of value here to point out, that it has already been shown from acidity data alone (Hollander, 1931, b) that “the major argument on which Rosemann based his opposition to the Heidenhain-Pavlov theory” is falla- cious. The present evidence only serves to complete the refutation of his picture of the secretory process.

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Studies in Gastric Secretion. IV

concentration and the maximum attainable acidity, has a mean value of 167 mM for all the data of this study. But this acidity- intercept value is in good agreement with that concentration of hydrochloric acid which is isotonic with mammalian blood (here- after designated as the isosmotic concentration of the acid).

Hill (1931) has estimated that the mean osmotic pressure of mammalian blood, calculated from data of Abderhalden on twelve different species, is equivalent to that of 0.1613 molal NaCl. This value is almost identical with the mean value for human blood as determined by Margaria (1930) under resting conditions. The freezing point depression corresponding to this concentration of NaCl is the same as that of a 157 mM HCl solution, as calculated from the data in the International Critical Tables. However, Margaria’s values, regardless of sex, fluctuate within f3 per cent of their mean; i.e., 0.907 to 0.962 gm. of NaCl per 100 gm. of water. Further, under conditions of exercise, the freezing point depression may be increased by as much as 11 per cent. Since the dogs used in the present work were never maintained in a state of complete rest, it follows that a concentration of hydrochloric acid which exceeds this isosmotic value by only 6 per cent (i.e. 167 mM as compared with 157 mru) is unquestionably isotonic within the limits of experimental variation. Therefore, a sample of gastric juice containing no neutral chloride would be isotonic with mammalian blood, and no acidity significantly higher than the acid concentration of such a solution can be attained under normal conditions. Thus, by extrapolation from the observed data, it can be shown that the two most significant prop- erties of the parietal secretion conform to the demands of our hypothesis.

Finally, a third point of agreement between the results of experiment and of theory can be established as follows: On the basis of a process of dilution and neutralization such as we have postulated, it is possible to develop equations for both total and neutral chlorides as functions of the acidity. Likewise, it is pos- sible to set up equations which describe the experimental graphs for these variables. When this was done, it was found that the empirical and theoretical equations possess certain specific char- acteristics in common, thus establishing another point of accord between observation and hypothesis. The mathematical develop- ment follows.

Throughout the discussion, symbols with single primes refer to the parietal secretion, those with double primes to the mucus- containing mixture, and letters without any primes relate to the mixed gastric juice. The following symbols are used:

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CHCl = total acidity cc1 = “ concentration of chloride CB =“ “ “ base CBCl = concentration of neutral chloride CBHCO, =

“ “ bicarbonate CO = the isosmotic concentration3

According to our theory, the parietal secretion is an isotonic solution of hydrochloric acid, which contains no other cations; we have, therefore,

C’Cl = c, (1)

C’B = 0 (2)

The alkaline component, however, constitutes a solution of organic matter (mucin, enzymes, etc.) in an isotonic mixture of neutral chloride and bicarbonate.4 Therefore,

c”C1 = C”CB,

C”B = C”BCI + C”BHCO~ = C,

Combining Equations 3 and 4, we get

(3)

(4)

C”c1 = C, - C”BHCO~ (5)

Now, gastric juice such as enters into this discussion contains free hydrochloric acid,5 and therefore all of its alkali and alkaline earth bicarbonate has been converted to neutral chloride by reac- tion with this acid. Thus

CB = CBCl (6)

CC1 = CBCl + ‘&Cl (7)

3 Since the present argument is only a first approximation, it is here assumed that the isosmotic concentration of hydrochloric acid is identical with that for the mixed neutral chlorides and bicarbonates, within the limits of error of this investigation.

* Throughout this discussion, minor constituents like the phosphate radical are considered so small as to be negligible in a first approximation.

6 This mathematical analysis can be developed in such a way as to in- clude gastric juice which possesses an “acid deficit” ; i.e., some unneutralized bicarbonate. The resulting complications, however, are hardly justified by the increase in mathematical rigor and universality which would be attained, and so the present discussion is restricted to acidity values greater than zero.

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600 Studies in Gastric Secretion. IV

and by combining Equations 6 and 7 we get

CHCl = ‘%I - CB (8)

Suppose that the acid and alkaline components are mixed in varying proportions to form a series of gastric juice samples of graded acidities, and let p = the fraction of parietal secretion in any one mixture, and (1 - p) = the fraction of the alkaline com- ponent. Then, for each of the resulting mixtures,

cc1 = p x C’Cl + (1 - PI x C”Cl (9)

cF3 = p x C’B + (1 - p) x C”‘B 00)

Substituting Equations 9 and 10 in Equation 8

CHCl = P x (C’Cl - C’B) + (1 - p) x (C”c1 - C”B) (11)

In order to obtain Cc, as a function of Cncl, let us solve Equa- tions 9 and 11 for p and equate the resulting expressions.

cc1 - C”C1 CHCl - (c”Cl - C”B)

c’cl - c”Cl = (c’cl - C’B) - (c”Cl - c”B) (12)

Substituting Equations 5, 1, 4, and 2 in Equation 12, we obtain

cc1 - (Co - C”BHC0,) CHCI - CC0 - C”BHCO* - Co 1

Co - (Co - C”BHCOA = (Co - 0) - CC0 - C”BHCO* - G 1

and finally, solving for Coi,

CC1 = CHCl x C”BEiCOa

co + C”BHCOa I[ + G2

Co + C”BHCO~ 1 (13)

Similarly, to obtain Cnor as a function of Cnoi, let us Solve Equations 10 and 11 for p and equate the resulting expressions.

CB - c”B CHCl - (C”Cl - C”B)

C’B - c”B = (C’Cl - C’B) - (c)‘Cl - c”B) 04)

Substituting Equations 6, 4, 5, 1, and 2 in Equation 14, we get

CBCl - C, C.cl - (Co - C”BHCO~ - Co 1

0 -co = (C, - 0) - (co - C”BHCOt - c,)

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F. Hollander 601

and finally, solving for Csoi, we obtain

CBCl = CHCl x C - ClJ

co + C”BHC0, I[ + co2

co + C”BHCOr 1 (15)

Since the bracketed fractions in Equations 13 and 14 are all parameters, these expressions are equations for a straight line in the intercept form, y = mx + b. They describe the relations, according to our hypothesis, among the variables Coi, Cnoi, and c nC1. But, the graphs representing the empirical relations among these variables may also be represented by equations in the inter- cept form as follows:

CC1 = ‘W31 x CHCl + ICl (13, 4

CBCl = mBC1 x CHCl + IBCl (15, a)

where Ioi and Inor are the intercepts on the vertical axes, and mcl and msol are the slopes of the respective lines. These slopes are given by the tangents of the angles which the lines make with the horizontal axes (see Columns 4 and 6 of Table I). Thus, Equations 13, a and 15, a, arrived at empirically, are identical in form with Equations 13 and 15 respectively, which were developed solely from theoretical considerations associated with our hypothesis.

It can also be shown that these two pairs of equations possess three specific characteristics in common. From Columns 4 and 6 of Table I we have

ma - mgc1= 1 (16)

From Equations 13 and 15, these two slopes are given by C”BHCOt

and - co

co + C”BHCOa co + C”BHC0, respectively. The algebraic dif-

ference of these expressions also equals one, which thus establishes a first point of identity. Again, from the empirical equations, we find that the ordinate intercepts are given by

ZCl = cc1 - mcl x CHCl (17)

IBCl = CBCl - mBC1 x CHCl 08)

Subtracting Equation 18 from Equation 17 we get

kl - IBCl = CC1 - CBCl - bW1 - nZBC1) x CHCl

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602 Studies in Gastric Secretion. IV

However, Coi = Csol + C noi and, from Equation 16, ??&I - msol = 1. Whence

ICI - &ccl = 0 Or ZCl = ZBCl (19)

But, the constant terms in Equations 13 and 15 are likewise

identical, being equal to co2

co + C"BHCOa Consequently, the two

pairs of equations are seen to possess a second characteristic in common. Finally, it was shown above that the experimental acidity intercept, IA, is equal to the “isosmotic concentration.” From Equation 15, however, we see that when csol = 0, CHCl = IA = C,. This establishes a third point of identity between the hypothetical and the empirical relations under consideration.

It is interesting to note that it is possible, from Equations 13, 15, 13, a, and 15, a and the corresponding graphs, to calculate the concentration of chloride in the alkaline constituent of the gastric juice. This has been carried out for the most representative graph (Fig. 3)) which is based on a greater number of samples than all the other graphs combined, and a value of 100 mM obtained. Since the actual composition of gastric mucus and the conditions which influence it are unknown, it remains for future investigation to decide whether the agreement of this value with that for blood plasma is significant or merely a coincidence.

Thus, it has been shown that not only are the experimental results in fundamental disagreement with the Rosemann theory, but that they conform in several specific respects to the demands of our own hypothesis. Although this does not constitute absolute proof, it follows with a high degree of probability, therefore, that the chloride ion of gastric pouch juice is derived in part from the parietal fluid and in part from the mucus and other secretions which are present in the pouch. As for the neutral chloride, this comes entirely from the neutral or alkaline components of the mixed juice; the major portion is secreted directly as such whereas the remainder is initially secreted as bicarbonate and subsequently converted to neutral chloride by interaction with the hydrochloric acid already present. The results also support our earlier con- tention that the normal fluctuations in acidity of pouch juice are not inherent in the parietal secretion but result from neutralization and dilution by mucus, etc.

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F. Hollander 603

SUMMARY AND CONCLUSIONS

1. The data here presented confirm the existence of a qualita- tive parallelism of the curves obtained by plotting the acidity and total chloride concentrations for pure gastric juice against the time. Likewise, the observations suggest an explanation for the occa- sional failure of other investigators to observe this phenomenon.

2. However, when the total chloride concentration and the acidity are plotted against each other, with the exclusion of time as a factor, the resulting graph is a straight line. This simple mathematical relation between the two variables has been demon- strated with data from a variety of sources.

3. Similarly, a straight line relation has been shown to exist between the neutral chloride concentration and the acidity.

4. A detailed hypothesis has been formulated to account for these quantitative variations in total and neutral chloride concen- trations, and also for the different types of acidity-time curves previously reported. This hypothesis assumes that pure gastric juice is a mixture of the parietal secretion with an alkaline fluid which is principally mucous secretion. The parietal secretion is essentially an isotonic solution of hydrochloric acid, and contains no fixed base. The alkaline component is an isotonic solution the principal constituents of which are neutral chlorides and bicar- bonates, the concentration of the former being appreciably greater than that of the latter.

5. Finally, it has been shown that the experimental findings support this hypothesis in the following respects: (a) As the acidity diminishes, the total chloride concentration also decreases but at a much lower rate. The Rosemann theory, on the contrary, presumes a concentration of chloride which is constant, inde- pendently of variations in acidity. (6) The maximum acidity which can be attained by gastric juice under normal conditions is that of a solution of hydrochloric acid which contains no neutral chloride and is isotonic with mammalian blood. (c) The mathe- matical equations relating the acidity with the total and neutral chloride concentrations, arrived at theoreticaIly, are identical in certain specific respects with the corresponding equations de- veloped from the experimental graphs.

In conclusion, therefore, it may be stated that the concentra-

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Studies in Gastric Secretion. IV

tions of total and neutral chloride in pure gastric juice are func- tions of the acidity in agreement with the above hypothesis. The process as pictured here, however, is only a first approximation; it now remains to extend it by studying the properties of the several constituent secretions which enter into the mixed gastric juice.

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Franklin HollanderTHEIR SIGNIFICANCE

CONTENT OF GASTRIC JUICE ANDVARIATIONS IN THE CHLORINE

STUDIES IN GASTRIC SECRETION: IV.

1932, 97:585-604.J. Biol. Chem. 

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