Effects of ketamine and propofol on autonomic cardiovascular function in chronically instrumented rats

In this study, we systematically examined the effects of ketamine and propofol at various doses (5-20 mg/kg) on blood pressure, heart rate and renal sympathetic nerve activity in chronically instrumented Wistar rats. We also assessed the effects of these anesthetics on the baroreflex control of heart rate and renal sympathetic nerve activity. Ketamine (10 mg/kg) increased blood pressure by 30.0+/-4.5%, heart rate by 17.7+/-3.3% and renal sympathetic nerve activity by 38.8+/-14.6%, while propofol (10 mg/kg) decreased blood pressure by 18.9+/-3.5%, heart rate by 5.5+/-2.5% and renal sympathetic nerve activity by 7.5+/-2.1%. These variables showed dose-dependent responses to both agents. Both ketamine and propofol decreased the range and maximum gain of the logistic function curve obtained by relating mean blood pressure to heart rate and blood pressure to renal sympathetic nerve activity. In conclusion, ketamine and propofol had different effects on autonomic cardiovascular function, but attenuated the baroreflex sensitivity of heart rate and renal sympathetic nerve activity in a dose-dependent manner. These results suggest the possibility that baroreflex sensitivity may reflect the depth of anesthesia. (C) 2001 Elsevier Science B.V. All rights reserved.