HEMODYNAMIC ACTIONS OF A NITRIC-OXIDE (EDRF) SYNTHESIS INHIBITOR IN CONSCIOUS BABOONS (PAPIO-HAMADRYAS)

1. The haemodynamic effects of intravenous nitric oxide inhibitor, N-n itro-L-arginine (NOLA), were examined in four conscious non-restrained baboons (Papio hamadryas). Mean arterial pressure, (MAP), systemic va scular resistance (SVR) and cardiac output (CO) were measured at timed intervals up to 24 h after a bolus injection of NOLA. 2. N-nitro-L-ar ginine increased blood pressure in a dose-dependent manlier up to 9.5 mg/kg. Increases in blood pressure were accompanied by increases in SV R and decreases in CO, with a significant fall in heart rate. 3. One a nimal received 9.5 mg/kg NOLA and became unconscious, suggesting cereb ral vasospasm. 4. Vascular effects of nitric oxide contribute signific antly to the regulation of arterial blood pressure under physiological conditions in the baboon.