Complicated central effects of endothelin on blood pressure in rats

The role of endothelin (ENT) in the control of systemic blood pressure (BP) was examined in conscious rats. Intracerebroventricular (i.c.v.) administration of ENT (0.002 or 0.2 micrograms, i.e., 0.78 or 78 pmol/2 microliters 0.9% saline) to conscious rats had complicated effects on BP. A significant fall in BP occurred in the initial 2-4 min after administration; and then after recovery toward the control level, BP decreased again within 17 min, following which a constant rise in BP occurred. In addition to the changes in BP, 3 of 9 rats which received 0.2 micrograms lapsed into severe barrel rotation-like behavior only to die 6-8 min after i.c.v. injection. It was therefore assumed that ENT had central effects on BP regulation and motor activity.