inhibitory effect of spironolactone on the …

Indian J Physiol Pharmacol 1994; 38(1) : 85-88

INHIBITORY EFFECT OF SPIRONOLACTONE ON THE CONTRACTIONS OFTHE RABBIT UTERINE HORN AND THE HUMAN MYOMETRIAL STRIP.

BEKIR COKSEVIM* AND MEHMET TAYYAR **

*Department ofPhysiology and**Department of Obstetrics and Gynecology,

Uni\lersilY of Erciyes, Faculty of Medicine,Kayseri, Turkey

( Received on July 12, 1993 )

Abstract: The spontaneous eon,rat:tions of the rabbit uterine horns and the humanmyometrial strips were stimulated by oxytocin ane! buscrclin acctate in isolated preparations.Spironolactone application to these models produced inhibitory effects on the contractions.It is concluded that spironolactone has inhibitory effcct on the rabbit uterine hom andthe human myometrial strip contractions.

Kc)' words: spironolactonc

INTRODUCTION

rabbit uterinc hom human myomctrial strip

rvIETHODS

Spironolactone (SP) is an aldosterone antagonistthat is used in the treatment of congestive heart failure,primary aldosteronism, hepatic ascites, essentialhypertension, hirsutism acne, precocious puberty, andpremenstruel tension (1,2,3 ,4,5,6).

In our upublished data on rats, we observedinhibitory effect of SP on the ileum, trachea and ulerine(all of them have smooth muscle) spontaneouscontractions. Up to date we did not coincide a manuscriptabout the effects of SP on the uterus. Therefore, weplanned to study the effect of SP on the humanmyometrium and the rabbit uterine horn.

We used oxytocin (Oxy) and a gonadotropinreleasing hormone (GnRH) agonist buserelin acetate(BA) to stimulate spontaneous contractions. Thestimulatory effect of GnRH agonist leuprolide acetateon the human myometrium firstly reported byKendall el al (7). We studied GnRH agonist BA onthe human myometrial strip and the rabbit uterinehorn motilities and observed the stimulatory effectof BA on the spontaneous uterine contractions (8).Because of this new knowledge we decided tostudy SP on the Oxy and BA stimulated uterinecontractions.

"Corresponding Author: P. K. 316, 38002 Kayseri. TUR KEY

The study was realised at the Erciyes UniversityPhysiological Experimental Laboratory. Female NewZealand white rabbits were used for the study and theirweights were 2500 g to 3000 g. Intraperitoneal thiopental30 mg/kg in dose was used to get general anasthesia.The abdomen of the rabbits were opened through aventral midline incision. The uterine horns were excisedand used for isolated preparations. The humanmyometrial strips were obtained from the tissues excisedat hysterectomy from the patients with dysfunctionaluterine bleeding.

The human myometrial strips and the rabbit uterinehorns were suspended in the organ bath containing 15ce of Lock-Ringer's solution. The temperature of thissolution was kept 37°C. It was aired by 95% oxygenand it's pH was 7.4. One end of the uterine hom andthe myometrial strip were applied to the transducer.The tension of 5 g was applied to the human myometrialstrip and 1 g tension was applied to the rabbit uterinehorn.

Control and experimental motility traces wererecorded by force displacement transducer (TB 611 TNihon Kohden) by using polygraphic system (RM 6000Nihon Kohden). Amplitude, duration and frequency of

86 Coksevim and Tayyar Indian J Physiol Pharmacol 1994; 38(2)

the contractions were observed andthe samples of the traces wererecorded during application of theagents (Oxy, BA, ritodrinehydrochloride (Rit), SP).

Oxy (Synpitan, Deva Co.,Istanbul, Turkey) was used in dose0.5 x 10_3 IU/ml to 1.0 x 10_2 lUI

mL) to stimulate contractions. Also,GnRH agonist BA (Suprefact,Hoechst, AG, Frankfurt, Germany)was used in doses 0.105 x 10-2 mglml to 1.05 x 10_2 mg/mlto stimulatecontractions. SP (PotassiumCanrenoate-Sanofi Chimie Co.,France) was used 0.1 x 10_3 mg/ml

to 0.2 x 10-3 mg/ml doses to inhibitthe contractions. Also, well knowntocolytic agent Rit (Prepar,Eczacibasi, Co., Istanbul, Turkey)was used 1.25 x 10_3 mg/ml to 2.5x 10_3 mg/ml to compare theinhibitory effect of SP.

Fig. I : Shows the inhibitory effect of SP on the Oxy stimulated human uterine myometrial strip.

lXIO- 3 mg/ml I,' ,.' I .'1'1'1

The inhibitory effects of SP on the stimulated

Fig, 2: Shows the inhibitory effect of SP on the Oxy stimulated rabbit uterine hom.The traces were analysedaccording to their amplitude,

tension, and inhibition percentage.Statistical analysis were performed using Student-t test.

RESULTS

spontaneous contractions are presented in Table I.Fig. 1 and 2 shows the inhibitory effect of SP on thecontractions of human myometrial strip and rabbit uterinehorn contractions which were stimulated by Oxy. Fig.

3 and 4 shows the inhibitory effect of SP on thecontractions of human myometrial strip and rabbit uterine

TABLE I :.The inhibitory effect of SP on the human myometrium strip and the rabbit uterine hom.

Induction (mm) Inhibition (mm) Inhibition (%)

The name of the prepartion Amplitude and Tension X ± SO X ± SO X ± SOOxy BA SP

8.48 ± 1.67 0.05 ± 0,01* 100.0Tension (mm).

Human Myometrial Strip 17.80 ± 8.15 5.20 ± 3.80* 64,0(n:IO) 21.00± 1.84 4.70 ± 2.27* 77.6

Amplitude (mm)37.10 ± 4.35 20.60 ± 4,96* 44,5

19.90 ± 1.64 2.25 ± 0,82* 88.6Rabbit Uterine Hom Tension (mm)(n:IO) 5.16 ± 3,9 2.50 ± 0.50· 51.5

27.40 ± 1.77 3.20 ± 0.10· 88.3Amplitude (mm) 29.5 ± 4,87 7.60 ± 0.90· 74.2

*Sutistical comparison showed statistically significanl difference when compared to the induction levels «P<0.05).

Indian J Physiol Phannacol 1994; 38(2) ~ffect of Spiroholacto.\\e on the Uterus 87

Fig. 4 : Shows the inhibitory effect of SP on the BA stimulated rabbit uterine hom.

Fig. 3 : Shows the inhibitory effect of SP on the BA stimulated human myometrial strip.

Also, we investigated Ritand SP on the Oxy stimulatedcontractions of the humanmyometrial strip in order tocompare their inhibitory effects(Fig. 5).

When the rabbit uterine homcontractions were stimulated byOxy the tension was inhibited88.6% by using SP. Whereas BAstimulated experiments showed51.5% inhibition. Statisticalanalyses revealed that tensionvalues got by inducing andinhibiting have significantdifferences (P<O.05). Amplitudelevels showed 88.3% inhibitionwhen SP applicated to the Oxystimulated contractions of therabbit .. terine horn. But, BAinducted contractions showed74.2% amplitude inhibition.Therefore, amplitude inhibitionvalues of SP showed statisticallysignificant (P<O.05) differencebetween Oxy and BA usedpreparations.

inhibition. Therefore, amplitudeinhibition values of SP showedstatistically significant (P<O.05)difference between Oxy and BAused preparations.

.=--1 _--'--';0:'-" ..__

--:: -=.-- lRit:l .'5 IO-3mQ/ml~~ - .i.'. tz

- o_Rlt:~ 5 'l)-3mq/ml .'"I"IO-~ t'n9/mHll...-....~--Oxy: /u III

Fig. 5 : Shows the inhibitory effect of Rit and SP on the Oxy stimulated human myometrial strip.

hom contractions which were stimulated by BA. DISCUSSION

When the human myometrial strip contractionswere stimulated by Oxy the tension was inhibited 100%by using SP. Whereas BA stimulated experimentsshowed 64% inhibition. Statistical analysis revealedthat tension values got by inducing and inhibiting havesignificant differences (P<O.05). Amplitude levels shows77.6% inhibition when SP applicated to the Oxystimulated contractions of the human myometrial strip.But. BA induced contractions showed 44.5% amplitude

In our unpublished data we used SP on the trachea,ileum, and uterus of the rat as isolated preparations,and we got inhibitory effects on their spontaneousactivities. Even we concluded that the SP could beused as toco!ytic agent. To get more support wereplanned the present study.

According to our data SP has inhibitory effect onthe BA and Oxy stimulated spontaneous contractionsof the rabbit hom and the human myometrial strip.

88 Coksevim and Tayyar Indian J Physiol Pharmacol t994; 38(2)

The tension was less reduced in the rabbit hom model.This is probably due to different contractions anddispersion of the receptors in the rabbit.

Probable pathways of inhibitory effect of SPare; (a) effect on the receptor level, (b) inhibition ofadenyl cyclase activity, (c) slow calcium channels similarto that calcium blockers, (d) inhibiting ATPase andcarbonic anhydrase, (e) modifying electrolyte transport(9,10,11,12). Further analyses shall reveal the exactpathway of inhibitory effect of SP.

To test the inhibitory effect of SP on thecontractions Rit was applicated to the preparations andcumulative doses of Rit produced amplitude and tensionincreamem. At that time SP was applicated to thepreparation. Then, the amplitude and tension were

dramatically reduced.

Rit is a worldwide used tocolytic agent. It hassome side effects (tachycardia, hypotension, chesttightness or actual pain, pulmonary edema,hyperglycemia, hypokalemia, lactic and ketoacidosis,emesis, headaches, tremulousness, fever andhallucinations) (13,14). Because of these side effectswe think that SP could be used as a 'tocolytic agenton some pregnant patients like cor pulmonale andcardiac failure, because it has also some useful effects(positive inotropic effect, potassium sparing effect(15,16).

In conclusion, SP has efficient inhibitory effecton the uterus contractions. Further clinical analysis shallclarify it's usage in obstetrics.

REFERENCES

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