Central site of the hypertensive action of bradykinin

The intraventricular injection of 1 mug of bradykinin (BK) in rats anesthetized with urethane (1.5 g/kg i.p.) caused an increase in mean arterial blood pressure with little or no change in pulse pressure or heart rate. A similar hypertensive response followed the local administration of 0.5 mug of BK at the pars ventralis of the lateral septal area, whereas local application at other subcortical regions, known to be involved in cardiovascular regulation, caused no effect. Injections of 0.5 or 1 mug of synthetic substance P or 1 mug of 9-desarginine-bradykinin at the pars ventralis of the lateral septal area caused no change in blood pressure. In addition, bilateral electrolytical lesions placed in the lateral septal area either markedly reduced or completely blocked the pressor response to intraventricular BK. These results suggest that the pars ventralis of the lateral septal area is involved in the pressor action of BK in the central nervous system. They also indicate that this brain region responds fairly specifically to BK and that local vascular changes are unlikely to be involved in the mediation of the central action of BK.