Adrenergic mechanism of the drugs. Systemic arterial pressure changes caused by intravenous injection of reserpine following the administration of pheniprazine and pyrogallol in anesthetized dogs.

It has been reported that reserpine causes a prolonged hypertension after the pretreatment of ephedrine and metamphetamine46'47. This hypertension was observed in the previous experiments and the mechanism of the drugs producing the hypertension was discussed. Pheniprazine was proposed as a monoamine oxidase inhibitor by Horita , and reserpine produced a prolonged hypertension after the administration of pheniprazine . A similar pheniprazine-induced reserpine hypertension was recognized in the present experiments, however, this hypertension was clearly different from the reserpine hypertension after ephedrine and metamphetamine. Furthermore, pyrogallol (a catechol-0-methyltransf erase inhibitor) was used prior to the administration of reserpine. Additionaly, the influence of bilateral adrenalectomy and the pheniprazine tachyphylactic dog were tested, and the mechanism of the drugs , especially the catecholamine releasing action of the drugs were discussed in this paper.