Stimulation of adenylate cyclase in homogenates of isolated intestinal epithelial cells from hamsters. Effects of gastrointestinal hormones, prostaglandins, and deoxycholic and ricinoleic acids

The mechanism by which intestinal secretagogues evoke fluid secretion in the small bowel and colon has been suggested to involve mucosal adenylate cyclase. Adenylate cyclase activity was assayed by conversion of [32P]ATP to [32P]cyclic AMP in a system of pure epithelial cells isolated from the small intestine of the hamster by vibration in buffer. Several gastrointestinal hormones were tested for their capacity to stimulate adenylate cyclase; vasoactive intestinal peptide and impure cholecystokinin-pancreozymin (but not the 99% pure preparation or pure cholecystokinin octapeptide) were potent stimuli, but pentagastrin, glucagon, secretin, and gastric inhibitory peptide were impotent. Two prostaglandins, PGE1 and PGE2, were potent stimuli of adenylate cyclase. Two other compounds that provoke intestinal secretion of fluid, deoxycholic acid and ricinoleic acid (castor oil), were ineffective stimuli of adenylate cyclase. These experiments do not support a clear-cut relationship between a compound's ability to stimulate adenylate cylase and its activity as an intestinal secretagogue.