Blood flow-dependent changes in intrarenal nitric oxide levels during anesthesia with halothane or sevoflurane.

We previously demonstrated that intrarenal nitric oxide (NO) levels and renal blood flow are reduced during halothane anesthesia. Studies were performed to determine if volatile anesthetics-induced reductions in renal NO levels are associated with blood flow changes. Halothane and sevoflurane at 0.8 and 2.4 Mac were administered by inhalation to dogs, and cGMP and NOx concentrations in the renal interstitial fluid were measured by a microdialysis method. Neither halothane nor sevoflurane at 0.8 Mac altered renal blood flow and renal interstitial cyclic guanosine monophosphate (cGMP) and NOx levels, but both anesthetics significantly decreased these values at 2.4 Mac. Using an adjustable aortic clamp, renal perfusion pressure was reduced in 2 steps without halothane and sevoflurane anesthesia. Renal blood flow as well as cGMP and NOx concentrations in the renal interstitial fluid were unchanged within the autoregulatory range, but significantly decreased below the autoregulatory range. Changes in cGMP and NOx concentrations in the renal interstitial fluid were highly correlated with renal blood flow changes during halothane or sevoflurane anesthesia, and during stepwise reductions in renal perfusion pressure. The results suggested that halothane- and sevoflurane-induced decreases in intrarenal NO levels result from reductions in blood flow.