CENTRALLY MEDIATED CARDIOVASCULAR EFFECTS OF ANGIOTENSIN II

¹ Department of Pharmacology, University of Pittsburgh School of Pharmacy,Pittsburgh, Pennsylvania

The intraventricular administration of angiotensin in chloralose-anesthetizedcats produced centrally mediated cardiovascular effects which consisted of hypertension and tachycardia and, in more than 50% of the experiments, contraction of the nictitating membrane. Section of the spinal cord at the C₁ level essentially abolished the response to intraventricularly administered angiotensin. The data presented suggest that physiologic levels of brain norepinephrine are necessary for the production of the angiotensin-induced pressor response following intraventricular administration and that either a reduction orelevation of brain norepinephrine significantly decreases the response. Additional data have been presented providing evidence that angiotensin acts directly or indirectly on centralsympathetic structures, thereby inducing a prolonged increase in peripheral blood pressure.The intraventricular administration of norepinephrine produced a centrally mediated hypotensive effect and bradycardia which could be reversed by "central depletion" of norepinephrine by reserpine or metaraminol.

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