PT - JOURNAL ARTICLE AU - O. D. GULATI AU - S. D. GOKHALE AU - H. M. PARIKH AU - B. P. UDWADIA AU - S. R. KRISHNAMURTY TI - EVIDENCE FOR A SYMPATHETIC <em>ALPHA</em> RECEPTOR BLOCKING ACTION OF <em>BETA</em> RECEPTOR BLOCKING AGENTS DP - 1969 Mar 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 35--43 VI - 166 IP - 1 4099 - http://jpet.aspetjournals.org/content/166/1/35.short 4100 - http://jpet.aspetjournals.org/content/166/1/35.full SO - J Pharmacol Exp Ther1969 Mar 01; 166 AB - Pronethalol, dichloroisoproterenol and d-, dl- and l-N-isopropyl-p-nitrophenylethanolamine blocked the contractile responses of the rabbit aortic strip to epinephrine and/or norepinephrine. Propranolol blocked the contractile responses of the rabbit aortic strip to methoxamine. Dichloroisoproterenol and pronethalol did not alter the responses to 5-hydroxytryptamine, angiotensin or acetylcholine but blocked the responses to histamine. Propranolol and N-isopropyl-p-nitrophenylethanolamine blocked the responses to 5-hydroxytryptamine and histamine but did not affect those to angiotensin and potentiated those to acetylcholine. Antagonism of the excitatory effects of epinephnine and norepinephnine by pronethalol, dichlonoisoproterenol and N-isopropyl-p-nitrophenylethanolamine and that of methoxamine by propranolol fulfilled the conditions of competitive antagonism. Antagonism by propranolol of the excitatory effects of histamine did not fulfill the conditions of competitive antagonism. © 1969, by The Williams &amp; Wilkins Company