无机电解质在不依赖胆汁酸的胆小管胆汁形成中的作用。

Role of inorganic electrolytes in bile acid-independent canalicular bile formation.

作者信息

Anwer M S, Hegner D

出版信息

Am J Physiol. 1983 Feb;244(2):G116-24. doi: 10.1152/ajpgi.1983.244.2.G116.

DOI:10.1152/ajpgi.1983.244.2.G116

Abstract

Ion-replacement studies were carried out in the isolated perfused rat liver to obtain insight into the role played by inorganic electrolytes in bile acid-independent canalicular bile flow (BAICF). The BAICF decreased significantly when Na+ (146 mM) was replaced by 120 mM K+, Rb+, Cs+, or choline and when Cl- (127 mM) was replaced by 120 mM acetate or isethionate; there was no reduction in BAICF when Na+ was replaced by Li+ (146 mM) and Cl- by NO-3. K+, Rb+, and Cs+, however, also caused a simultaneous decline in the perfusion rate. The BAICF decreased by 50% when HCO-3 was replaced by equimolar tricine; under this condition replacement of Cl- by NO-3, but not Na+ by Li+, decreased BAICF by 45%. Thus the hepatic transport of Cl- cannot be explained by simple diffusion only, and a special mechanism, probably Na+-coupled Cl- transport, may contribute about 30% of the BAICF. With Li+ replacing Na+ in the medium, the intracellular concentration of Li+ in isolated rat hepatocytes was less than that calculated for electrochemical equilibrium and was increased by 2 mM KCN, indicating active extrusion of this ion. Li+ was unable to activate Mg2+-ATPase of isolated rat liver plasma membranes, and 1 mM ouabain did not affect the Li+ distribution. These results suggest the potential importance of ion pumps other than Na+-K+-ATPase in BAICF.

摘要

在离体灌注大鼠肝脏中进行了离子置换研究，以深入了解无机电解质在不依赖胆汁酸的胆小管胆汁流（BAICF）中所起的作用。当用120 mM的K⁺、Rb⁺、Cs⁺或胆碱替代Na⁺（146 mM），以及用120 mM的乙酸盐或羟乙基磺酸盐替代Cl⁻（127 mM）时，BAICF显著降低；当用Li⁺（146 mM）替代Na⁺且用NO₃⁻替代Cl⁻时，BAICF没有降低。然而，K⁺、Rb⁺和Cs⁺也会同时导致灌注速率下降。当用等摩尔的三（羟甲基）甲基甘氨酸替代HCO₃⁻时，BAICF降低了50%；在这种情况下，用NO₃⁻替代Cl⁻而非用Li⁺替代Na⁺会使BAICF降低45%。因此，Cl⁻的肝脏转运不能仅用简单扩散来解释，一种特殊机制，可能是Na⁺偶联的Cl⁻转运，可能对BAICF贡献约30%。在培养基中用Li⁺替代Na⁺时，离体大鼠肝细胞内Li⁺的浓度低于电化学平衡计算值，并且被2 mM的KCN增加，表明该离子的主动外排。Li⁺无法激活离体大鼠肝细胞膜的Mg²⁺ - ATP酶，并且1 mM的哇巴因不影响Li⁺的分布。这些结果表明，除了Na⁺ - K⁺ - ATP酶之外的离子泵在BAICF中可能具有重要作用。