Calcium-calmodulin-dependent activation of adenylate cyclase in prostaglandin-induced electrically-monitored intestinal secretion in the rat.

The calcium-calmodulin antagonist 5-iodo-C8-W7 inhibited the PGE2-induced stimulation of cAMP production by isolated enterocytes from rat small intestine. It also reduced the secretory response of intestinal sheets to PGE2, measured as a rise in short-circuit current. It did not however, inhibit the electrical responses to forskolin and dibutyryl cAMP, nor to acetylcholine, a secretagogue whose effect is not mediated by cAMP. It is concluded that the receptor-mediated activation of adenylate cyclase and the subsequent secretory response are dependent upon calcium-calmodulin.