Effects of nimodipine on brain blood flow following acute brain ischemia in the newborn piglet.

We examined the effect of the calcium channel blocker nimodipine on postischemic hypoperfusion in the newborn piglet brain. A severe pneumothorax (SP) was induced by injecting air into the right thorax until the mean arterial blood pressure fell to 25% of baseline and was maintained for 4 min. Blood flow was immediately reduced 70-90% from baseline in each brain region during SP. In untreated animals postischemic hypoperfusion existed at 60 min, following recovery from SP with regional brain blood flow reduced 20-30% from baseline. Nimodipine infusion after SP prevented postischemic hypoperfusion in all brain regions and increased blood flows by as much as 40% above baseline in midbrain and brainstem structures. Nimodipine infusion began after severe brain ischemia prevented postischemic hypoperfusion and enhanced brain blood flow in this model.