Physiologic responses to intravenous serotonin in the awake squirrel monkey.

Intravenous injections of serotonin in the monkey produces bradycardia and arrythmias, apnea followed by tachypnea, urination, and penile erection. These effects were not altered by anesthesia. Special consideration is given to the role of chemical and neural factors in the genital response, a reaction heretofore not noted in other species. An assortment of evidence suggests that this response is attributable to the local effect of serotonin on the genital vasculature.