Effects of nitrous oxide on liver haemodynamics and oxygen consumption in the greyhound

The effects of increasing concentrations of nitrous oxide 30, 50 and 70% on the hepatic circulation and hepatic oxygen consumption were investigated in seven normocapnic greyhounds. Hepatic arterial and portal venous blood flows were measured continuously using electromagnetic flow probes, and mean arterial pressure and cardiac output monitored. The administration of nitrous oxide caused linear decreases in hepatic arterial, portal venous and total liver blood flows. Increases in mean arterial pressure, hepatic arterial resistance and mesenteric vascular resistance were noted. There were no significant changes in hepatic oxygen consumption. It is suggested that the decrease in liver blood flow may result from alpha-adrenoceptor stimulation.