Phosphorylation and activation of tyrosine hydroxylase mediate the acetylcholine-induced increase in catecholamine biosynthesis in adrenal chromaffin cells.

Abstract

Acetylcholine, the natural secretagogue, increased catecholamine biosynthesis in isolated purified bovine adrenal chromaffin cells.This effect was calcium dependent, mimicked by other secretagogues such as carbamyl choline, veratridine, elevated KCI, and A23187, and antagonized by blockers of depolarization-dependent calcium influx (MnCL, MgC12, DBOO).Acetylcholine did not influence the rate of 3,4-dihydroxyphenylalanine decarboxylation in situ, and neither elevated tyrosine (100 PM), exogenous pterin (1 mM), nor exogenous catecholamines (up to 1 m) attenuated the increase in catecholamine biosynthesis produced by acetylcholine.Tyrosine hydroxylase activity, measured in vitro after sonication of the cells, was increased by prior treatment of the chromaffin cells with acetylcholine.And, acetylcholine increased 32P incorporation into tyrosine hydroxylase within intact chromaffin cells preincubated with 32Pi.The activation of the enzyme required extracellular calcium, and the phosphorylation of the enzyme was inhibited by either MnClz or ethylene glycol his@-aminoethyl ether)-NjVJV'&"tetraacetic acid.In the preceding report (Meligeni, J.