title: The response of plasma catecholamines to the vasodepression caused by beta-adrenoceptor antagonists in the spontaneously hypertensive rat.
abstract: The 15-20% decrease in mean arterial pressure (MAP) seen in conscious spontaneously hypertensive rats (SHR) after the administration of a single dose of the beta-adrenoceptor antagonists atenolol, betaxolol, oxprenolol, pindolol, propranolol or sotalol was not accompanied by an increase in plasma norepinephrine (NE) concentration. In marked contrast, plasma NE concentration increased by 50-75% when MAP was lowered at the same rate, and to the same extent with the vasodilator minoxidil. Atenolol, betaxolol and propranolol significantly suppressed plasma renin activity (PRA), whereas oxprenolol, pindolol and sotalol did not alter PRA significantly. Based on these observations, I conclude that beta-adrenoceptor antagonists impair the normal baroreflexly-mediated increase in plasma NE concentration which occurs in response to a decrease in MAP and this sympatho-inhibitory effect does not require the suppression of renin release.
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D006973:Hypertension / Q000188:drug therapy* / Q000235:genetics; D008297:Male; D008914:Minoxidil / Q000494:pharmacology; D009638:Norepinephrine / Q000097:blood*; D051381:Rats; D011918:Rats, Inbred SHR / Q000502:physiology*; D011919:Rats, Inbred Strains / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000187:drug effects*
chemical_list: D000319:Adrenergic beta-Antagonists; D008914:Minoxidil; D009638:Norepinephrine