PORCINE MALIGNANT HYPERTHERMIA. VII: HEPATIC METABOLISM

Hepatic metabolism during porcine malignant hyperthermia (MH) was investigated in seven Pietrain pigs. The estimated hepatic blood flow decreased during MH, but an increase in oxygen extraction enabled the splanchnic oxygen uptake to be maintained. There was a large release of glucose and potassium from the liver in MH which made an important contribution to the hyperglycaemia and hyperkalaemia. Measurement of hepatic uptake of the precursors of gluconeogenesis, lactate, glycerol and alanine, showed that glucose efflux from liver was derived mainly from glycogenolysis. Lactate uptake by the liver increased during MH, and there was no evidence of hepatic lactate production during the profound acidosis as suggested by in vitro studies with the isolated liver. There was no evidence of major abnormality of hepatic function during porcine MH. t- t Changes in circulating metabolites during porcine malignant hyperthennia (MH) have been described in detail (Berman et al., 1970; Jones et al, 1972; Lucke, Hall and Lister, 1976) and are considered to be secondary to the increased muscle metabolism, although the contribution of other organs and tissues cannot be discounted. In this study with Pietrain pigs, we have examined liver function during the hyperthermic response to determine the contribution of liver metabolism to concentrations of substrates in the blood. In parti-cular, the progressive lactic acidosis characteristic of MH may result from both increased anaerobic muscle metabolism and impaired lactate uptake by the liver. There is considerable evidence from in vitro studies of the liver that an acidic perfusate reduces lactate uptake and also causes hepatic lactate production (Hems et al., 1966; Lloyd et al., 1973; lies et al., 1977). If this mechanism operates in porcine MH, it could be responsible for the fulmin-ating nature of the acidosis