ROLE OF 2ND MESSENGERS IN THE RELEASE OF MOTILIN FROM ISOLATED CANINEINTESTINAL-CELLS

We examined the intracellular mechanisms for the release of motilin in a preparation of mucosal cells obtained from dog duodenum. Enzymatica lly dispersed cells were separated by counterflow elutriation to enric h motilin content. Postreceptor activation process was studied by comp aring the release of motilin obtained with exogenous analogues or stim ulants of the various intrecellular signal pathways. Dibutyryl cyclic adenosine monosphate (10(-3) M) and forskolin (10(-5) M) induced a mod erate response in motilin secretion. Phorbol ester beta-phorphol-12-my ristate-13-acetate and phospholipase C were potent stimulants of motil in release. Raising intracellular calcium concentration by calcium ion ophore A23187 or increasing calcium content in the incubation milieu f ailed to modify the secretion of motilin. Analogues of 8-bromoguanosin e-3'5' cyclic monosphosphate were ineffective. Therefore, the motilin cell was very sensitive to protein kinase C activators and appeared mo derately responsive to a stimulation of the adenylate cyclase pathway.