397 CHOLESTYRAMINE TNHIBITION OF JEJUNAL NaSECRETOH IN SMALL BOWEL BACTERIAL COLONIDATION

The effect of cholestyramine(Ch)on cAMP-mediated jejunal Na+secretion associated with increased luminal free fatty acids(FFA) and deconjugated bile salts(DBS)during bacterial colonization of the small bowel was studied.Male Wistar rats(70-90 gm) were injected with mecamylamine HCl for 3 days, to induce bacterial proliferation in the upper small bowel(MC);controls received NaCl(C). Half of each group were fed Ch 4% in the diet.Supernatants of small intestinal contents were assayed for FFA and DBS;jejunal mucosa was examined for cAMP and ATPases;jejunal Na+transport was measured by in vivo perfusion with Krebs-Henseleit buffer.MC rats not fed Ch had higher luminal concentrations of FFA and DBS as compared to C(FFA:.21±.03 vs .13±.003 mEq/l;p<.02. DBS: 1.11 vs .23 mM).They also had elevated cAMP(34.14±6.17 vs 10.7±2.73 pmol/mg protein;p<.01)and a marked Na+efflux into the jejunum(secretion of 101.07±33.5 vs absorption of 90.15±14.9 µEq/min/cm;p<.001). Feeding Ch to MC rats inhibited these effects:FFA and DBS were lower than in C and CAMP did not differ from C.While Na+efflux was noted in MC rats,Na+absorption did occur in MC rats fed Ch (38.14±21.6 µEq/min/cm;p<.001).The ATPases were similar in all groups. The data indicate that the cAMP-mediated jejunal Na secretion and the increased luminal FFA and DBS during small intestinal bacterial colonization is inhibited by oral Ch,which binds these products and renders them innocuous.