Winkler K, Henriksen J H, Tygstrup N
Department of Clinical Physiology, Hvidovre Hospital, Denmark.
Am J Physiol. 1993 Jul;265(1 Pt 1):G9-14. doi: 10.1152/ajpgi.1993.265.1.G9.
Galactose elimination capacity is used as a quantitative measure of liver function on the assumption that galactose elimination outside the liver is negligible or easily corrected for. The relationship between hepatic and extrahepatic removal of galactose was studied in anesthetized pigs during quasi-steady-state conditions by continuous infusion of galactose. The hepatic removal approximated a constant [maximal velocity = 585 +/- 41 mumol/min, Michaelis constant (Km) = 0.24 +/- 0.07 mmol/l, mean +/- SE, n = 20]. The renal removal was less than the amount filtered, showing maximal tubular reabsorption (Tm 178 +/- 3.0 mumol/min, Km 3.8 +/- 0.9 mmol/l, n = 20). Metabolic conversion of galactose in the kidney was not demonstrable. At all concentrations studied (0.4-5.8 mmol/l), total galactose elimination from the body exceeded the sum of hepatic and renal elimination by approximately 100 mumol/min, independent of the concentration. At blood concentrations usually used for clinical estimation of the galactose elimination capacity (approximately 4 mmol/l), hepatic removal in the pig accounted for 55% and renal removal for 30% of total removal; 15% of removal occurred in other organs. We conclude that estimation of the hepatic galactose elimination capacity from whole body elimination curves requires correction for renal removal of galactose.
半乳糖清除能力被用作肝功能的定量指标，其假设前提是肝脏外的半乳糖清除可忽略不计或易于校正。通过持续输注半乳糖，在麻醉猪的准稳态条件下研究了肝脏和肝脏外对半乳糖清除的关系。肝脏清除近似为常数[最大速度 = 585±41 μmol/min，米氏常数（Km）= 0.24±0.07 mmol/L，均值±标准误，n = 20]。肾脏清除小于滤过量，显示出最大肾小管重吸收（Tm 178±3.0 μmol/min，Km 3.8±0.9 mmol/L，n = 20）。未证实半乳糖在肾脏中的代谢转化。在所有研究浓度（0.4 - 5.8 mmol/L）下，机体总的半乳糖清除量超过肝脏和肾脏清除量之和约100 μmol/min，与浓度无关。在通常用于临床评估半乳糖清除能力的血浓度（约4 mmol/L）下，猪的肝脏清除占总清除量的55%，肾脏清除占30%；15%的清除发生在其他器官。我们得出结论，根据全身清除曲线估计肝脏半乳糖清除能力需要校正肾脏对半乳糖的清除。
