[Effect of phenoxybenzamine on the experimental cerebral vasospasm in cats (author's transl)]

Effects of topical and intravenous administration of phenoxybenzamine (PBZ) on the experimental vasospasm were studied in cats. Cerebral vasospasm was produced by a topical application of blood, prostaglandin (PG) E2 or PGF2alpha to be exposed basilar artery. Topical PBZ caused a significant dilatation of the basilar artery and the occurrence of vasospasm was completely prevented either with blood, PGE2 or PGF2alpha. Intravenous administration of PBZ in the dosage with which the pressor response to phenylephrine was completely blocked, or three times that dosage, failed to show any preventive effect on the vasospasm. From these experimental results, it seems that the antispasmogenic action of topically applied PBZ is due largely to the non-spacific vasodilator action of PBZ and not to its alpha adrenergic blocking action. It is also suggested that the role of alpha adrenergic mechanism in the genesis of vasospasm in this experimental design is not significant.