Epinephrine Prepotency Over Pressoreceptor Responses Elicited by Elevated Blood Pressure

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Abstract
The blood pressure effects of progressively increasing doses of intravenously injected 1-epinephrine were determined on ten dogs anesthetized with 30 mg. of pentobarbital sodium per kg. The dogs were fully atropinized (test: vagal block to tetanic stimulation) after a midcervical left vagotomy. The same doses of epinephrine were repeated. Comparison of results before and after atropine and vagotomy showed no significant differences in: control blood pressure; magnitude of rises; peak blood pressures; and dose-response curve parameters. The 2 largest doses of epinephrine, 10 [mu]g. and 50 [mu]g./kg., showed greater mean duration of the pressor phase of the blood pressure at probability levels, respectively, of 0.05 < P < .1 and 0.025 < P < .05. It appears that the pressoreceptors are ineffective in moderating the vascular responses to injected epinephrine and, analogously, to secreted epinephrine. Postulate: the pressoreceptors are of little importance in protection against generalized hypertension; their function is reflex protection against hypotension.