EFFECTS OF KETAMINE HCL ON CARDIOPULMONARY FUNCTION IN SNAKES

We determined the effects of ketamine HCl on cardiopulmonary function in 10 grey ratsnakes (Elaphe obsoleta), weighing 320 +/- 150 g (mean /- SD). To establish normal values of cardiovascular response, we meas ured arterial blood pressure, carotid arterial blood flow, heart rates , breathing rates, and arterial blood gases in conscious snakes positi oned both horizontally and in a 45 degrees head-up tilt. Then we measu red the same variables following intravascular administration of ketam ine HCl (41 +/- 6 mg/kg), Administration of ketamine produced signific ant tachycardia, hypertension, and decreases in breathing rates which were reflected in modest changes of arterial pH and respiratory gas pr essures. Arterial oxygen saturation, however, exceeded 95% in both con scious and anesthetized snakes, Administration of ketamine produced ne arly twofold increases in systolic, diastolic, mean, and pulse systemi c arterial pressures of resting snakes in horizontal position. In resp onse to head-up tilt, central arterial pressures decreased in anesthet ized snakes but did not fall below levels that were regulated by refle xogenic increases in conscious snakes, Thus, administration of ketamin e HCl to snakes produced significant hypertension but did not seriousl y compromise cardiovascular performance in response to gravitational s tress.