Effects of the intravenously administered anaesthetics ketamine, propofol, and thiamylal on the cortical renal blood flow in rats.

Intravenous anaesthetics such as ketamine, propofol, and thiamylal are widely used, although the direct effects of these anaesthetics on the renal blood flow (RBF) have not been well elucidated. In this study, we examined the effects of bolus and continuous administrations of ketamine, propofol, and thiamylal on cortical RBF and the effects of noradrenaline (NA) on RBF under continuous administration of these anaesthetics. We used laser Doppler flowmetry to measure the effects of bolus injection and continuous infusion of ketamine, propofol, and thiamylal on cortical RBF in male Wistar rats. We also examined the effects of the anaesthetics on mean arterial blood pressure (MAP) and heart rate (HR). Bolus injections of ketamine, propofol, or thiamylal (1-8 mg/kg each, n = 10) at clinically relevant concentrations did not affect MAP, HR, or RBF. Continuous administration of ketamine, propofol, or thiamylal (1-8 mg/kg/h each, n = 10) did not affect MAP, HR or RBF. Exogenous NA (2 microg/kg) caused an increase in MAP and a decrease in RBF and HR. In experiments with continuous infusions of propofol or thiamylal (1-8 mg/kg/h each, n = 10), similar results were observed without infusion of any anaesthetics. However, bolus injection of NA did not result in a decrease in RBF during continuous ketamine infusion (98.8 +/- 6.7% of control, n = 6, p < 0.05), while ketamine did not affect the NA-induced increase in MAP. In conclusion, bolus and continuous administrations of ketamine, propofol, and thiamylal did not affect the RBF. From our present findings, ketamine would be useful for maintaining the RBF.