SYSTEMIC HYPOXIA AND HYPEROXIA, AND LIVER BLOOD-FLOW AND OXYGEN-CONSUMPTION IN THE GREYHOUND

The effects of systemic hypoxia upon liver blood flow and oxygen consumption were studied in a group of six pentobarbitone anaesthetised greyhounds. The effect of systemic hyperoxia upon the same factors were also studied in a further group of six greyhounds. Hypoxia studied at PaO2 tensions of 9.3, 7.3, 5.3 and 3.3 kPa was found to increase mean arterial pressure significantly at each PaO2 tension studied immediately the hypoxic gas mixture was introduced but this pressure had returned to control by the time 20 min had passed. At the same time a significant decrease in hepatic arterial blood flow was seen, returning to control by 20 min. No significant changes were seen in portal venous blood flow. Hepatic arterial and mesenteric vascular resistance increased significantly immediately hypoxia was instituted at all PaO2 tensions. Hepatic oxygen consumption, measured after 20 min, decreased at all PaO2 tensions, significantly at 3.3 kPa (25 mm Hg). Hepatic venous oxygen content decreased significantly at each PaO2, decreasing to 20% of control at 3.3 kPa (25 mm Hg). Hyperoxia studied at PaO2 tensions of 26.6, 39.9 and 53.2 kPa produced no significant effects upon liver blood flow. However, there was a small increase in hepatic oxygen consumption. © 1979 Springer-Verlag.