Effects of nimodipine on acute focal cerebral ischemia.

Nimodipine is a calcium slow channel blocker with several pharmacologic properties suggesting the potential to favorably modify outcome in focal cerebral ischemia. Thirty adult cats underwent unilateral middle cerebral artery (MCA) occlusion for 4 hours. Seventeen cats were treated with an ipsilateral intracarotid infusion of nimodipine (1 microgram kg-1 min -1) beginning 15 minutes before MCA occlusion and continuing throughout the occlusion period. Eight nimodipine treated cats maintaining MAP greater than 90 mmHg were assigned to a Higher Pressure Nimodipine (HPN) group. The remaining nine treated cats with MAP less than 90 mmHg were assigned to the Lower Pressure Nimodipine (LPN) group. Thirteen cats were untreated, receiving an isovolumetric amount of vehicle through the ipsilateral carotid artery. Local cerebral blood flow (ICBF) was continuously monitored using thermal diffusion probes. The brains, assessed for colloidal carbon perfusion, fluorescein and Evans blue staining, electroencephalographic activity (EEG), and histological changes, revealed no significant differences by any of these methods between the HPN and control animals with the exceptions of: HPN treated cats exhibited a preservation of EEG activity at 15 minutes post-occlusion compared to the untreated cats, and Post-ischemic surface colloidal carbon perfusion was better preserved in the treated cats than in the untreated cats. Mild hypotension, as demonstrated by the LPN group, negated these two positive effects. Prior to MCA occlusion, ICBF was bilaterally significantly increased after nimodipine infusion in the HPN group as compared to vehicle infusion. Intra-arterially infused nimodipine did not reduce infarct size.