Blockade of the systemic and renal vascular actions of angiotensisn II with the 1-sar, 8-ala analogue in the rat.

To assess the characteristics of blockade induced by 1-Sar, 8-Ala angiotensin II (P113) in the rat, dose-response relationships were established for angiotensin II and blood pressure, cardiac output and renal blood flow (measured with microspheres) and calculated total peripheral resistance. P113 infused at 1.0 μg/kg/min reduced renal and systemic vascular responses to angiotensin II, but did not modify the pressor response because of compensatory increase in cardiac output. Ganglionic blockade (pentolinium tartrate 2.5 mg) uncovered a significant influence of P113 at 1.0 μg/kg/ min on pressor responses to angiotensin II. P113 at 10 μg/kg/min totally prevented the pressor and renal vascular response to 1.0 μg/kg/min of angiotensin II. P113 at 10 and 100 μg/kg/min did not influence renal blood flow, cardiac output or total peripheral resistance, and had only a transient, small influence on blood pressure. P113 did not modify the renal or systemic vascular response to norepinephrine. The failure of P113 to influence renal blood flow in the rat and the relative insensitivity of the renal vasculature to angiotensin II suggest that the vascular receptor for angiotensin II in the rat differs from that in other species including the dog, rabbit and man.