AJP - Regulatory, Integrative and Comparative Physiology, Vol 258, Issue 5 1230-R1237, Copyright © 1990 by American Physiological Society
Hemodynamic and behavioral effects of angiotensin II in conscious sheep
B. A. Breuhaus and J. E. Chimoskey
College of Veterinary Medicine, North Carolina State University, Raleigh 27606.
Intracerebroventricular (ivt) angiotensin II (ANG II) at 0.4, 2, 10, and 50
ng.kg-1.min-1 increased arterial pressure in conscious sheep in a
dose-related manner (26 mmHg, P less than 0.05, at 50 ng.kg-1.min-1). Total
peripheral resistance (TPR) and right atrial pressure also increased. Heart
rate, stroke volume, and cardiac output did not change. Pressor responses
to ivt ANG II were not caused by leakage of ANG II into the periphery,
because plasma concentrations of ANG II did not change from control (31 +/-
7 pg/ml) at the highest dose of ANG II infused. In contrast, intravenous
(iv) ANG II, 10 and 50 ng.kg-1.min-1, increased arterial pressure 29 and 47
mmHg, respectively (P less than 0.05), and decreased heart rate. ANG II, 10
ng.kg-1.min-1 iv, increased plasma ANG II levels from 36 +/- 6 to 354 +/-
69 pg/ml (P less than 0.05). Intracarotid (ic) ANG II, 10 ng.kg-1.min-1,
increased arterial pressure 31 mmHg (P less than 0.05) but did not alter
heart rate. ANG II ivt caused a dose-related drinking response, with a
positive correlation between the amount of water drunk during ivt ANG II
infusion and the increase in arterial pressure. Infusions of ANG II at 50
ng.kg-1.min-1 ivt were associated with decreased plasma osmolality and
potassium concentration and increased plasma vasopressin concentration.
