Enhancement of noradrenaline release by 12-O-tetradecanoyl phorbol-13-acetate, an activator of protein kinase C.

12-O-Tetradecanoyl phorbol-13-acetate (TPA), an activator of protein kinase C (PKC), enhanced the electrically evoked overflow of [3H]noradrenaline in a concentration-dependent manner in rabbit hippocampal slices. 4-O-Methyl-TPA, which lacks the ability to activate PKC had no effect on the evoked tritium overflow. The enhancement of noradrenaline release by TPA was affected by neither the alpha 2-adrenoceptor antagonist yohimbine nor the alpha 2-adrenoceptor agonist clonidine. It is concluded from these results that PKC is involved in the mechanism of stimulus-secretion coupling in noradrenergic nerve terminals of the rabbit hippocampus.