Inhibition of catecholamine release by alpha-adrenergic activation: interaction with Na, K-ATPase.
In rat adrenal gland incubated in vitro, phenylephrine and naphazoline inhibited the release of catecholamines (CA) induced in a medium containing K+ (5.6mM). In K+-free medium or in the presence of ouabain (10(-3) M) phenylephrine and naphazoline had no effect on CA release. The alpha-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 of alpha-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.
D000109:Acetylcholine / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism*; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D002395:Catecholamines / Q000378:metabolism*; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008861:Microsomes / Q000201:enzymology; D009278:Naphazoline / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D010643:Phenoxybenzamine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011458:Prostaglandins E / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D002395:Catecholamines; D011458:Prostaglandins E; D010643:Phenoxybenzamine; D010656:Phenylephrine; D010042:Ouabain; D012964:Sodium; D000251:Adenosine Triphosphatases; D009278:Naphazoline; D008274:Magnesium; D000109:Acetylcholine; D011188:Potassium; D010646:Phentolamine