In a controlled double blind experiment the influence of a continuous i.v. infusion of
Nimodipine (1 microgram kg-1 min-1) upon
infarct size, histopathology and neurological outcome in rats with permanent middle cerebral artery (MCA) occlusion was examined. The infusion was started 20 min. before the induction of
ischemia and continued 4 hours thereafter. The
nimodipine treated animals were subdivided into hypotensive (MABP lower than 85 mmHG for more than 5 minutes after
arterial occlusion) and normotensive groups.
Infarction size, documented by TTC, H&E and Nissl staining was significantly smaller (p less than 0.001) in
nimodipine normtonic rats than the lesions in placebo and saline treated rats, as well as compared with hypotonic
nimodipine animals (largest
infarction). These differences were found to be entirely at the expense of the cortical (frontoparietal) component of the lesion, suggesting "penumbra" action of the
drug. Moreover,
nimodipine normotonic rats displayed lower cortical neuronal injury in the periinfarct zone. These findings were corroborated by corresponding better neurological scores. Our results indicate that
nimodipine is effective in reducing focal
cerebral ischemia, provided the MABP is maintained higher than 85 mmHg.