Tissue amine levels and sympathetic blockade after guanethidine and bretylium.
A single dose of guanethidine produces a substantial, long-lasting depletion of tissue catecholamines in the rat, whereas a similar dose of bretylium has no effect. Both drugs produce block of the eserine-induced sympathetic pressor effect. Block by guanethidine is induced more rapidly than is amine depletion. When amine depletion is maximal, a noradrenaline infusion is capable of restoring the response to eserine, but no restoration of the response to eserine occurs after noradrenaline infusion into bretylium-treated rats. Catecholamine levels in isolated tissues are not reduced when complete block of sympathetic nerve stimulation has been produced by guanethidine. It is suggested that guanethidine possesses a primary bretylium-like, and a secondary reserpine-like, blocking action. Guanethidine produces a transient lowering of intestinal 5-hydroxytryptamine, and this coincides with increased intestinal motility.
D000578:Amidines / Q000494:pharmacology*; D000818:Animals; D001340:Autonomic Nerve Block; D001949:Bretylium Compounds; D002395:Catecholamines / Q000378:metabolism*; D006145:Guanethidine; D009638:Norepinephrine; D051381:Rats; D012110:Reserpine; D012701:Serotonin; D013564:Sympathetic Nervous System
D000578:Amidines; D001949:Bretylium Compounds; D002395:Catecholamines; D012701:Serotonin; D012110:Reserpine; C045166:bretylium; D009638:Norepinephrine; D006145:Guanethidine
AMIDINES/pharmacology; CATECHOLAMINES/metabolism