Protein kinase C activators 1,2-oleoylacetylglycerol (OAG, 0.5-50 microM), a synthetic diacylglycerol analog, and phorbol-12,13-dibutyrate (Pb(Bu)2, 0.016-1.6 microM) depressed the calcium (Ca)-dependent components of action potentials in isolated superior cervical ganglion cells of rabbits. Similar depressions were elicited when the M2-muscarinic receptors were activated. This muscarinic modification of the action potential was obscured after the perfusion with protein kinase C inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7, 50 microM). It seems that protein kinase C is an intermediator between the M2-muscarinic receptors and the Ca channels regulating the firing rate of the postganglionic cells.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine Action Potentials