Central and peripheral cardiovascular actions of urapidil in normotensive and Goldblatt hypertensive animals.

The central effect of urapidil on mean arterial blood pressure, heart rate, and reflex tachycardia was studied in anesthetized normotensive and Goldblatt hypertensive dogs and anesthetized cats. The administration of 1 mg intracisternally of urapidil decreased blood pressure and heart rate in normotensive dogs, whereas 2 and 4 mg decreased heart rate and returned blood pressure to the control level. Reflex tachycardia evoked by the intravenous administration of bradykinin was suppressed in a dose-dependent manner by urapidil. In the anesthetized cat, urapidil was administered intracisternally (50 to 400 micrograms) and had no effect on heart rate. The reflex bradycardia elicited by central vagal nerve stimulation was accentuated by urapidil given intracisternally, but this only occurred in the presence of beta adrenoceptor blockade with propranolol.