Preservation of baroreflex control of vascular resistance under ketamine anesthesia in rats.

The aim of this study was to examine the effects of ketamine and pentobarbital on the baroreceptor reflex control of vascular resistance in rats. The gains of baroreflex were assessed by relating changes in arterial pressure to changes in hindlimb perfusion pressure, using an extracorporeal perfusion circuit with a delay system. Reflex-induced vasodilation or vasoconstriction in response to a rise or a fall in arterial pressure were elicited by injections of phenylephrine or nitroprusside, respectively. The gains of baroreflex were not altered by ketamine 1 and 5 mg/kg (i.v.), whereas those were depressed by pentobarbital 5 mg/kg (i.v.). The results suggest that ketamine preserves the baroreflex control of vascular resistance and pentobarbital depresses it. The preservation of the baroreflex control of vascular resistance may be advantageous for patients with hypovolemia to sustain the blood pressure.