Difference between Halothane and Barbiturate Anesthesia in the Influence of Cerebral Ischemia on the Vagal Barorflex in Dogs

In halothane-anesthetized dogs, a decrease in baroreflex sensitivity (BRS) of approximately 20% was observed during the reperfusion period following 5-min global cerebral ischemia. When compared with our previous study on animals under pentobarbital anesthesia, the extent of the decrease in BRS was smaller and apparently more severe ischemia was necessary to damage the vagal component of the baroreflex. Substitution of halothane with pentobarbital during the reperfusion period failed to affect either BRS or the ratio of the vagal component. In another group, pre- and post-ischemic measurements of BRS was performed under halothane anesthesia, but the ischemic insult was given under thiopental anesthesia. In these animals, the extent of decrease in BRS (about 50%) was greater than that in animals subjected to ischemia under halothane anesthesia. The present results suggest that the anesthetics used during the ischemic insult may affect the extent of post-ischemic dysfunction of the baroreflex. The vagal component of the baroreflex may be more resistant to ischemia under halothane anesthesia than under barbiturate anesthesia.