Inhibitory effects of calmodulin antagonists on isoproterenol- and dibutyryl cyclic AMP-stimulated amylase release from rat parotid acinar cells.

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Abstract
The effects of three calmodulin antagonists on rat parotid amylase release were investigated in vitro using a dispersed acinar cell preparation. The potent calmodulin antagonists, trifluoperazine (TFP) and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), inhibited both 1 .mu.M isoproterenol (ISO)- and 1 mM dibutyryl cyclic AMP (DBcAMP)-stimulated amylase release in a dose-dependent manner at concentrations of 25-100 .mu.M. The IC50 values for the ISO-stimulated amylase release were 22 .mu.M with TFP and 42 .mu.M with W-7, and the values for the DBcAMP-stimulated release were 25 .mu.M and 48 .mu.M, respectively. The weak calmodulin antagonist, N-(6-aminohexyl)-1-naphthalene-sulfonamide (W-5), caused only slight inhibition at a concentration of 100 .mu.M. These calmodulin antagonists only had a very small effect on the spontaneous release of lactate dehydrogenase. The results suggest that the calcium-calmodulin system may play a role in the exocytotic process of amylase release from the rat parotid gland.