[Experimental study on intrahepatic gas tensions measured by mass spectrometry: effect on temporary occlusion of the afferent hepatic circulation].

: In 24 mongrel dogs, a mass spectrometer was utilized to measure intrahepatic pO2 and pCO2 levels subjected to various degrees of inspired oxygen concentration, or interruption of the afferent hepatic circulation. The mean intrahepatic pO2 and pCO2 levels in dogs breathing 70% O2 were 46.0 +/- 13.3(SD) mmHg and 27.4 +/- 13.0mmHg, respectively. Progressive rise of the intrahepatic pO2 and pCO2 was observed with increase in the arterial pO2 and pCO2 when the hepatic circulation was kept constant. When the hepatic artery was interrupted, mean intrahepatic pO2 fell rapidly to 20% of the control value, and mean intrahepatic pCO2 rose to 200%. Rather wide dispersion of the values among the experimental animals during the hepatic artery interruption was speculated to reflect the variety of collateral hepatic arterial supply and various degrees of congestion of portal blood flow. Transient decrease in the mean intrahepatic pO2 was observed following interruption of the portal vein. Intrahepatic pO2 rapidly fell to zero and pCO2 increased in a lineal fashion when the total hepatic circulation was interrupted. The latter rose to 453% of the control value 30 minutes after interruption, then the rate of rise gradually decreased until a plateau was reached one hour later. This decrease in the rate of rise in intrahepatic pCO2 was regarded to reflect the reduction of energy production through the anerobic pathway due to irreversible hepatic parenchymal degeneration. It is suggested that the measurement of intrahepatic gas tensions under various conditions by a mass spectrometer technique is useful for evaluating changes of intrahepatic microcirculation and dynamic aspects of anerobic metabolism of the liver.