Effects of nilvadipine (a dihydropyridine-type calcium entry blocker) on cerebral blood flow in acute experimental brain ischemia in rats.

Abstract

The purpose of the present study was to examine the effect of nilvadipine (a dihydropyridine-type calcium entry blocker) on the cerebral circulation, experimental models of cerebral ischemia were used to measure abrupt changes in the cortical cerebral blood flow (CBF) at the 'penumbra' (the boundary region between the anterior cerebral artery (ACA) and the middle cerebral artery (MCA)). Left middle cerebral artery occlusion (MCAO) was performed in Sprague--Dawley rats, and then 8 or 16 micrograms kg-1 of nilvadipine was administered to two groups of the rats. The former group was referred to as the 8-MCAO(+) group (n = 8), and the latter group, the 16-MCAO(+) group (n = 8). To a control group (n = 8), only the solvent of nilvadipine was administered. After the administration in each group, CBF and the mean arterial blood pressure (MAP) were continuously measured for 60 min. The MAP in both the 8-MCAO(+) and 16-MCAO(+) groups was significantly lower than in the control group for 25 min after nilvadipine administration (Wilcoxon 2 sample test, p < 0.05). Also, the CBF in the 16-MCAO(+) group was significantly lower (about 20%) for 55 minutes than that in the control group. On the other hand, the CBF in the 8-MCAO(+) group three minutes after nilvadipine administration was not significantly lower than in the control group (Wilcoxon 2 sample test). Our findings confirmed that nilvadipine (8 micrograms kg-1) maintained CBF while lowering the blood pressure in the experimental model of acute cerebral ischemia.