[The effect of prazosin hydrochloride on cerebral vasospasm--an experimental study]

The effect of Prazosin, a new alpha-receptor blocking agent, to release and prevent experimental cerebral vasospasm induced by oxyhemoglobin was investigated. In the first group of cats Prazosin was administered one hour before the induction of vasospasm by oxyhemoglobin, and thirty minutes after the application of oxyhemoglobin in the second group. Doses of 0.5 mg/kg and 0.1 mg/kg were subjected to both groups respectively. In the third group, the divided administration of Prazosin was done; 0.05 mg/kg was given one hour before and two hours after the application of oxyhemoglobin. In the first group, prevention of vasospasm was observed. In the second group, induced vasospasm was released from three hours after the administration of Prazosin. These effects were seemed to be dependent on doses of Prazosin. In the third group, more constant prevention of vasospasm was observed than the former groups. The possible mechanism of preventing and releasing effect of Prazosin on cerebral vasospasm was discussed.