Local effect of anaesthesia on cerebral blood flow in the rat.

Abstract

Local blood flow was measured in 81 cerebral structures of the paralysed rat during nitrous oxide, sodium pentobarbital and glucochloralose anaesthesia. With a ventilatory mixture of 75% nitrous oxide and 25% oxygen the flow values in comparable structures were slightly lower than those reported in awake animals. Pentobarbital and chloralose depressed the local flow by an average of 32 +/- 2% and 39 +/- 2%, respectively, as compared to values measured during nitrous oxide administration. In some areas the flow was reduced below 40% of the control, whereas other regions showed no significant change at all. Based on the coefficients of correlation, the distribution of local flow values is similar under pentobarbital and chloralose, but differs considerably from the pattern observed during nitrous oxide anaesthesia. The results indicate that the effect of anaesthesia on cerebral blood supply depends a great deal on local factors, and experimental data collected under different types of anaesthesia are not directly comparable.