Inhibition of catecholamine release by alpha-adrenergic activation: Interaction with Na, K-ATPase

Publisher Website
Google Scholar
Abstract
In rat adrenal gland incubatedin vitro, phenylephrine and naphazoline inhibited the release of catecholamines (CA) induced in a medium containing K+ (5.6 mM). In K+-free medium or in the presence of ouabain (10−3 M) phenylephrine and naphazoline had no effect on CA release. Theα-adrenergic blockers, phentolamine and phenoxybenzamine, increased CA release in a K+-medium but had no effect on CA release from adrenal medulla in a K+-free or ouabain (10−3 M) containing medium. PGE2 inhibited the release of CA both in the presence and in the absence of K+, as well as in the presence of ouabain (10−3 M). Activation ofα-adrenergic receptors in the adrenal medulla by phenylephrine and naphazoline resulted in increased Na, K-ATPase activity but no effect on Mg-ATPase. PGE2 acts through a different mechanism.