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THE ROLE OF GLUTATHIONE IN BILE SECRETION OF ENDOGENOUS TRACE-ELEMENTS IN RATS

DIJKSTRA, M., KUIPERS, F., SMIT, EP., HAVINGA, R. & VONK, RJ., Jun-1993, In : Journal of Laboratory and Clinical Medicine. 121, 6, p. 751-758 8 p.

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To evaluate the role of glutathione in biliary secretion of endogenous trace elements, we quantitated trace element output rates by proton-induced x-ray emission under various conditions with altered biliary glutathione secretion and hepatic glutathione content in the rat. Treatment with phenobarbital (80 mg/kg body weight, 4 days), ethanol (0.9 gm/kg body weight, 4 days), or diethylmaleate (3.9 mmol/kg body weight) resulted in changes in biliary glutathione secretion of +114%, -56%, and -95%, respectively, and in hepatic glutathione content of -0%, +25%, and -86%, respectively, when compared with control values. Biliary glutathione level was below detection limits in mutant Groningen Yellow Wistar rats, whereas hepatic glutathione content was increased by 114% in these animals. Glutathione secretion showed a linear relationship with bile flow when data from all experiments were included in the analysis; the apparent choleretic activity of glutathione was 67 mul/mumol. Six trace elements (iron, zinc, copper, manganese, molybdenum, bromine) could always be detected in bile. Potassium and calcium were measured for comparative purposes. No relation was found between biliary trace element secretion and hepatic glutathione content. Biliary output rates of iron, molybdenum, and bromine correlated, albeit poorly, with biliary glutathione efflux (r values: iron, 0.67; molybdenum, 0.40; bromine, 0.53; respectively). Copper, manganese, and zinc secretion did not show any consistent relationship with glutathione secretion. The secretion rates of iron, molybdenum, and bromine, like that of calcium, showed a highly significant correlation with bile flow (r values: iron, 0.89; molybdenum, 0.75; bromine, 0.80; and calcium, 0.90; respectively, p <0.001). Multiple regression analysis, with trace element secretion as the dependent variable and bile flow and glutathione secretion as the independent variables, revealed that bile flow, but not glutathione, significantly contributes to regulation of trace element secretion. Bile secretion of iron, molybdenum, and bromine also significantly correlated with that of the freely permeable cation potassium, with intercepts of the regression lines near zero. The data indicate that glutathione does not ploy a direct regulatory role in bile secretion of the major endogenous trace elements in rats. However, biliary glutathione indirectly provides a driving force for the secretion of iron, molybdenum, and bromine by Stimulating bile flow.

Original languageEnglish
Pages (from-to)751-758
Number of pages8
JournalJournal of Laboratory and Clinical Medicine
Volume121
Issue number6
Publication statusPublished - Jun-1993

    Keywords

  • EXPERIMENTAL IRON OVERLOAD, BILIARY CALCIUM SECRETION, HEPATOCYTE LYSOSOMES, COPPER EXCRETION, FLOW, DIETHYLMALEATE, ZINC, TRANSPORT, DOG

ID: 6351748