Stimulation of mucosal bicarbonate secretion in rat duodenum in vivo by BW755C

Abstract

HCO3- secretion from 12 mm segments of duodenum just distal to the Brunner''s gland area was titrated (pH 7.60) in situ in anesthetized rats. I.v. BW755C (10-20 mg/kg) increased both HCO3- secretion and the transmucosal electrical potential difference and pretreatment with indomethacin (3 mg/kg i.v.) prevented these effects. Indomethacin also inhibited stimulation of HCO3- secretion by luminal acid (10 mM HCl) but had no effect on the rise in secretion in response to exogenous (luminal) prostaglandin [PG]E2. Evidently the endogenous PG mediate the HCO3- response to acid, consistent with the demonstration that BW755C increased PG formation in homogenates of rat intestinal mucosa. Stimulation of HCO3- secretion by BW755C was not enhanced but attenuated by preexposure to luminal acid; the latter apparently increases secretion by effects other than mucosal mobilization of arachidonate.