Mechanism of Arterial Pressure Response to Histamine-Liberators

¹ From the Research Division, Cleveland Clinic Foundation and the Frank E. Bunts Educational Institute Cleveland, Ohio

Experiments with pharmacologic blocking agents indicate that, in the barbiturate anesthetized rat, the depressor response to injected histamine-liberators is attributable to the release into the circulation of a mixture of serotonin and histamine. The data do not suggest participation of any other depressor agent. The effect of such release on blood pressure can be simulated by infusion of a mixture of serotonin and histamine, indicating that the depressor response to endogenous release or exogenous administration is undistinguishable, although tissue responses are very different. The depressor responses to histamine liberators or to infusions of histamine-serotonin mixtures can be suppressed by pretreatment with an antihistamine such as promethazine and an antiserotonin agent such as BOL. Inhibition is also obtained with drugs possessing both properties such as phenoxybenzamine.