Kan K S, Coleman R
Department of Biochemistry, University of Birmingham, Edgbaston, U.K.
Biochem J. 1988 Dec 15;256(3):1039-41. doi: 10.1042/bj2561039.
The effect of an increase in intracellular Ca2+ concentration on tight-junctional permeability in rat liver was studied by using the calcium ionophore A23187. Infusion of 100 microliters of dimethyl sulphoxide containing various amounts of A23187 over 30 min into isolated perfused livers was followed by a pulse of horseradish peroxidase (HRP) under single-pass conditions. The first biliary HRP peak, a measure of junctional permeability, was increased 4-fold with 100 micrograms of A23187. There were, however, no significant effects on bile flow or on aspartate aminotransferase leakage as compared with the control at this dosage, and thus the increase in junctional permeability was occurring without evidence of appreciable cholestatic or hepatocellular damage. Higher dosages of A23187, however, caused not only an increase in HRP peak height but also changes in bile flow and increases in aminotransferase leakage, indicating more extensive effects at these higher dosages. A second peak of HRP secretion, occurring 20-25 min after the HRP pulse, was also elevated approx. 3.5-fold; this may indicate that pinocytosis and transcellular movement of HRP are also increased under these conditions.
利用钙离子载体A23187研究了细胞内钙离子浓度升高对大鼠肝脏紧密连接通透性的影响。在30分钟内，将含有不同量A23187的100微升二甲基亚砜注入离体灌注肝脏，然后在单通道条件下注入辣根过氧化物酶（HRP）脉冲。作为连接通透性指标的第一个胆汁HRP峰，在加入100微克A23187后增加了4倍。然而，在此剂量下，与对照组相比，胆汁流量或天冬氨酸转氨酶泄漏没有显著影响，因此连接通透性增加时没有明显胆汁淤积或肝细胞损伤的迹象。然而，更高剂量的A23187不仅导致HRP峰高度增加，还引起胆汁流量变化和转氨酶泄漏增加，表明在这些更高剂量下有更广泛的影响。HRP脉冲后20 - 25分钟出现的第二个HRP分泌峰也升高了约3.5倍；这可能表明在这些条件下，HRP的胞饮作用和跨细胞转运也增加了。
