Effects of hyperglycemia on quantitative liver functions by the galactose load test in diabetic rats

Blood galactose clearance after an intravenous galactose load has been widely used as a quantitative liver function test. We have developed a novel quantitative rat liver function test, the galactose single point (GSP) method, to assess residual liver function with various injuries by measuring single time point galactose concentration in blood after an intravenous bolus injection of galactose. The goal of this study was to evaluate the influence of nonhepatic factors such as hyperglycemia on GSP and galactose elimination capacity (GEC) in rats. Four groups of animal studies were carried out, as follows: (1) normal control (NC), (2) streptozotocin-induced diabetes (DM), (3) carbon tetrachloride-induced hepatotoxicity (CCl(4)), and (4) streptozotocin-induced diabetes with CCl(4)-induced hepatotoxicity (DM + CCl(4)). The serum glucose levels in the diabetic groups (DM and DM + CCl(4)) were significantly increased compared with the NC and CCl(4) groups (P < .001). A significant increase in hepatic activities of aspartate aminotransferase and alanine aminotransferase was observed in the CCl(4)-treated groups (CCl(4) and DM + CCl(4)) compared with the NC and DM groups (P < .001). In comparison with the NC group, the values of GSP and GEC in the diabetic groups (DM and DM + CCl(4)) were significantly reduced (P < .001) and increased (P < .01), respectively. Galactose single point had highly significant correlations with GEC (P < .001). These results suggest that galactose metabolism tests-as quantitative parameters of liver function-should be interpreted with caution in the condition of a significant hyperglycemia.