Abstract
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.
Footnotes
- Received October 24, 1967.
- Accepted September 17, 1968.
- © 1969, by The Williams & Wilkins Company
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