Nimodipine does not increase cerebral blood flow during subarachnoid hemorrhage in the rat.

The purpose of this study was to determine the effects of nimodipine, a calcium antagonist, on regional cerebral blood flow (CBF) in experimental subarachnoid hemorrhage (SAH) rats. Regional CBF was measured by the radioactive microspheres method. Experimental SAH was induced by a single injection of autologous arterial blood (0.3 ml) into the cisterna magna in anesthetized rats. Rats subjected to SAH showed an immediate and marked reduction of CBF in all brain regions throughout the experimental period. The infusion of nimodipine (1 microgram/kg/min) was started 30 min before the induction of the experimental SAH and continued during the experiments. Nimodipine did not prevent the reduction of regional CBF after SAH. It is concluded that nimodipine only increases regional CBF in normal animals, but dose not affect the reduction of CBF after experimental SAH.