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

In this study, we systematically examined the effects of ketamine and propo fol at various doses (5-20 mg/kg) on blood pressure, heart rate and renal s ympathetic nerve activity in chronically instrumented Wistar rats. We also assessed the effects of these anesthetics on the baroreflex control of hear t 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 sympathe tic nerve activity by 38.8+/-14.6%, while propofol (10 mg/kg) decreased blo od 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 respons es to both agents. Both ketamine and propofol decreased the range and maxim um gain of the logistic function curve obtained by relating mean blood pres sure to heart rate and blood pressure to renal sympathetic nerve activity. In conclusion, ketamine and propofol had different effects on autonomic car diovascular function, but attenuated the baroreflex sensitivity of heart ra te and renal sympathetic nerve activity in a dose-dependent manner. These r esults suggest the possibility that baroreflex sensitivity may reflect the depth of anesthesia. (C) 2001 Elsevier Science B.V. All rights reserved.