Effect of Intracisternal Injection of Endothelin-1 on Regional Cerebral Blood Flow in Cats

The effect of endothelin-1 on regional cerebral blood flow (rCBF) was investigated in adult mongrel cats. Endothelin-1 was injected into the cisterna magna and rCBF was measured by the hydrogen clearance method before and every 30 minutes for 180 minutes after the injection. Endothelin-1 (10-11 mol and 10-9 mol) induced a significant decrease in rCBF and an increase in arterial pressure. The effects of endothelin-1 on rCBF and arterial pressure were mediated, at least in part, by Ca2+, because pretreatment with intracisternally injected nicardipine prevented the changes. Cerebral angiograms obtained before and after endothelin-1 injection demonstrated severe constriction of the basilar artery, but constriction of the internal carotid and middle cerebral arteries was mild. Since the rCBF measured was in the territory of the middle cerebral artery, the decrease in blood flow was probably not solely due to the artery constriction. Other mechanisms such as arteriole constriction and/or regulation of rCBF by the central nervous system may also occur.