Effects of phencyclidine and ketamine on cardiovascular activity and temperature in the squirrel monkey

Heart rate (HR), mean arterial blood pressure (BP) and core temperature (TEMP) were recorded from chair-restrained squirrel monkeys surgically prepared with chronically indwelling arterial and venous catheters to determine the effects of acute intravenous (i.v.) injections of phencyclidine and ketamine and intramuscular (i.m.) injections of ketamine. Phencyclidine (0.03-3.0 mg/kg) and ketamine (0.3-30.0 mg/kg) i.v. increased BP and decreased TEMP, and the changes in BP and in TEMP were greater in magnitude and duration after phencyclidine. Heart rate also increased monotonically after 0.03-0.3 mg/kg phencyclidine or 0.3-10.0 mg/kg ketamine, but the effects of higher doses of either drug were biphasic with decreases followed by increases in HR. When either of two doses of ketamine (10.0 and 30.0 mg/kg) was injected i.m., the effects were qualitatively similar to those observed after i.v. administration although of much less magnitude, and there was no evidence of a biphasic change in HR. The data show that these two dissociative anesthetics differ in duration of action and in magnitude of effect on cardiovascular activity and core temperature in the squirrel monkey, and that phencyclidine is approximately ten times as potent as ketamine.