Effects of Angiotensin II on the Cardiac Responses to Sympathetic Nerve Stimulation in Dogs

• Published in: Hypertension (Dallas, Tex. 1979) Tex. 1979), 1983-01, Vol.5 (1), p.26-33
• Main Authors: FURUKAWA, YASUYUKI, SCIPIONE, PAUL, LEVY, MATTHEW N
• Format: Article
• Language: English
• Subjects: Angiotensin II - pharmacology; Animals; Blood Pressure - drug effects; Dogs; Dose-Response Relationship, Drug; Electric Stimulation; Heart Rate - drug effects; Myocardial Contraction - drug effects; Sympathetic Nervous System - physiology
• ISSN: 0194-911X; 1524-4563
• DOI: 10.1161/01.hyp.5.1.26

In anesthetized dogs with the left cardiac sympathetic nerves and both vagal nerves intact, angiotensin II (All) induced a substantial, dose-dependent increase in arterial blood pressure and small increments in cardiac cycle length and ventricular contractile force. In dogs in which the cardiac sympathetic and vagal nerves had been interrupted, All produced similar increases in blood pressure and larger increases in contractile force, but it decreased the cardiac cycle length. In both groups of dogs, All augmented substantially the positive inotropic responses to sympathetic nerve stimulation, but it enhanced the positive chronotropic responses only slightly. However, AH did not appreciably prolong the cardiac responses to sympathetic nerve stimulation, nor did it alter signifi-cantly the cardiac responses to norepinephrine infusions. Hence, at the dosage levels used, All probably did not inhibit the neuronal uptake of norepinephrine appreciably nor did it enhance the responsiveness of the cardiac effector sites to norepinephrine. Therefore, the potentiation of the cardiac responses to sympathetic nerve stimulation by All in these experiments was probably achieved principally by facilitating norepinephrine release from the adrenergic nerve terminals in the heart.