Human colonic adenylate cyclase. Stimulation of enzyme activity by vasoactive intestinal peptide and various prostaglandins via distinct receptor sites

The effects of meclofenamic acid on basal and hormone-stimulated adenylate cyclase in human colonic mucosa were tested. It is shown that meclofenamic acid is a relatively specific inhibitor of the stimulatory action of prostaglandins on the level of mucosal adenylate cyclase. This compound did not inhibit significantly the effects of vasoactive intestinal peptide (VIP) on the human enzyme system. VIP18-28 did not act as a partial agonist and did not inhibit the response to the intact VIP. Our studies suggest the existence of distinct receptor sites for both secretagogues (VIP and prostaglandins) in human colonic mucosa.