P29 GASTROINTESTINAL RESPONSE TO ORAL VERSUS JEJUNAL FEEDING OF DEFINED FORMU- LA DIETS. E.A.Voung, L.A.Cioletti, V.Ealderas and M.Taylor. Dept.of Med., Univ. of Texas Health Science Center, San Antonio, TX T8284.

The gastrointestinal response to oral versus continuous jejunal feeding of a variety of defined formula diets (DFD) was compared. Male Sprague- Dawley rats (ZOO-2509) were randomly assigned to 2 experimental groups: group O,sham-operated, orally-fed, and group J, operated, jejunally-fed. Subsets of animals in each group were isocalorically nourished exclusively on one of the following diets: Vivonex (V), Flexical (F), Vital (Vit), or Vivonex HN (VHN). Urine (24hr) was collected every other day and assayed for total nitrogen. After 2 weeks rats were killed and the liver and small intestine removed. The intestine was divided into 8 equal segments and weighed. Mucosal weight, protein and DNA per cm segment were determined. Liver weight and lipid content were measured. The rate of weight gain over the Z-wk period of 0 and J groups was significant (ANOVA<0.005), due mainly to specific diet effect. All animals were maintained in positive N balance, with N retention being significantly greater (p& 0.01) in VHN and Vit animals (400-600 mg/day) than in V or F animals (200-250 mg/day). While liver weights (g and %body weight) were similar in all 0 and J groups fANOVA. NS). liver lioid content was sianificantlv different fANOVA. p< O.GO5):.V-fed animals accumulated the most lipid (0 = 10.69 + 2:58%, J = 17.51 + 3.23%) compared to animals on the other three diets. Intesti- nal segment weight and mucosal weight, protein and DNA showed a normal pro- ximal to distal decreasing gradient on all 0 animals, while all J animals showed significantly increased intestinal mass in segments 2-5 correspon- ding to the site of jejunal infusion. Significant differences in gut mass were also noted between specific DFD (ANOVA, p< 0.05 - p< 0.005), with V animals consistently maintaining lowest gut mass. Conclusion: Gastroin- testinal responses to isocaloric DFD are significantly modified by jejunal versus oral feeding, as well as by the specific diet used. (Supported by Abbot Laboratories, Chicago, IL).

P3OSTUDIES ON THE ABSORPTION OF OLIOPEPTIDES AND FREE AMINO ACIDS IN ELEMEN- TAL DIETS. Yoshiya Mashima and Ken-ichi Yamazaki. 1st Surg.Dept.,Chiba Univ., School of M d e ., Ch' lba City and Terumo Co., Hatagaya, Shibuyaku, Tokyo, Japan.

It has been suggested that di- and tri-peptides are more rapidly ab- sorbed from the small intestine than free amino acid (AA), and thus, more suited for the nitrogen source of elemental diets. Recent availability of the egg albumin hydrolysate (80% of the content are di-and tri- peptides) promted us to examine this theory by performing a series of obsorption studies on Thiry-Vella loops in 6 mongrel dogs (10 to 12 kg). The length of the isolated intestinal loop (upper jejunum) was 40 cm. Twenty-five percent solution of the formulated elemental diet (Carbohydrate 68%, AA or the peptides 18.8%). or 5% solution of the protein hydrolysates or the equivalent AA were infused continuouslv bv Holter numo from the oral ori- fice of the loop at the speed of 0.05 ml/min/kg. After initial infusion for 30 min. for equilibration, the fifteen minute samplings of the dis- charge through the distal orifice were performed 4 or 5 times for each solution, followed bv the same studies with a different solution. after one hour interval. C-14 polyethylene glycol was added to the perfusing solution as a volume indicator. The discharge was analyzed for nitrogen content and C-14 radioactivity. The orders of the solutions were randomly altered. The calculated nitrogen absorption rates of the solutions were (1) 65.3 2 9.6 % (n=6) for the oligopeptide solution, (2) 46.1 + 22.7 % (n=6) for AA solution, (3) 40.4 + 12.7% (n=22) for the elemental diet with the oligopeptide, and (4)'29.7-t-11.7 % (n = IS) for the elemental diet with AA mixture (Mean value + SD). The difference between the values of (3) and (4) is significant (p 0101). These results indicate that the oli- gopeptides presently examined are more easily absorbed in the intestine than the equivalent AA mixtures, even at the existent of a large amount of carbohydrate component, which tendet to decrease the absorption rate of both nitrogen sources.

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