Measurement of ischemic changes in cerebral blood flow by the hydrogen clearance technique and brain cortical temperature. Influence of flunarizine.

In dogs global cerebral ischemia was produced by clamping reversibly the left subclavian and brachiocephalic arteries, supplying the head. The intercostal arteries were ligated permanently. Cerebral blood flow (CBF) was measured discontinuously using a hydrogen saturation-desaturation technique. Clamping of the former two vessels caused an increase in systemic blood pressure. When this increase was not blunted by previous splenectomy and blood withdrawal a still important CBF remained during the clamp. However, if this rise in blood pressure was impaired, CBF decreased to 9 +/- 8% (mean +/- S.D., n = 14) of the pre-ischemic value. Flunarizine is known to have anti-hypoxic/ischemic properties. The influence of this drug (0.1 mg/kg i.v.), injected 10 min after the beginning of a 30-min ischemia period, on the post-ischemic CBF was investigated. Two-three hour after ischemia CBF was significantly lower in the solvent-treated animals than in the flunarizine-treated group, in which CBF approached the preischemic values. Changes in CBF were also followed continuously by measurement of the variations of brain versus aortic temperature. It was analyzed what information this can provide on CBF.