Effects of ethanol and diabetes on galactose oxidative metabolism and elimination in rats

Blood galactose clearance after an intravenous galactose load has been wide ly used for years as an index of liver function. We developed a noninvasive [C-13]galactose breath test, which explores galactose oxidative metabolism ; this test is well correlated with liver fibrosis in patients with chronic Viral hepatitis. The goal of this study was to evaluate the influence of n onhepatic factors such as diabetes and ethanol on whole-body galactose clea rance (measured as the serum galactose elimination capacity test) and oxida tive metabolism (measured as the [C-13]galactose-induced breath (CO2)-C-13 production) in rats. Acute ethanol administration induced a significant dec rease of galactose clearance and (CO2)-C-13 production. There was a signifi cant correlation between the amount of ethanol given and the inhibition of galactose metabolism (R-2 = 0.72, p < 0.0001). In streptozotocin-induced di abetic rats, the [C-13]galactose-induced breath (CO2)-C-13, production was significantly reduced (p < 0.0001) and normalized by insulin treatment. How ever, diabetes did not decrease whole-body galactose clearance, indicating an isotopic dilution of [C-13]glucose produced from [C-13]galactose metabol ism into the enlarged glucose pool. These results must be taken into accoun t when using the [C-13]galactose breath test as a quantitative liver functi on test.