Combettes L, Berthon B, Doucet E, Erlinger S, Claret M
Institut National de la Santé et de la Recherche Médicale, Unité de Recherche 274, Université Paris-Sud, France.
Eur J Biochem. 1990 Jul 5;190(3):619-23. doi: 10.1111/j.1432-1033.1990.tb15617.x.
In the present study, we investigated the possible role of external Ca2+ in the rise of the cytosolic Ca+ concentration induced by the monohydroxy bile acid taurolithocholate in isolated rat liver cells. The results showed that: (a) the bile acid promotes the same dose-dependent increase in the cytosolic Ca+ concentration (half-maximal effect at 23 microM) in hepatocytes incubated in the presence of 1.2 mM Ca2+ or 6 microM Ca2+; (b) taurolithocholate is able to activate the Ca2(+)-dependent glycogen phosphorylase a by 6.3-fold and 6.0-fold in high and low Ca2+ media, respectively; (c) [14C]taurolithocholate influx is not affected by external Ca2+, and 45Ca2+ influx is not altered by taurolithocholate. These results establish that the effects of taurolithocholate on cell Ca2+ do not require extracellular Ca2+ and are consistent with the view that monohydroxy bile acids primarily release Ca2+ from the endoplasmic reticulum in the liver.
在本研究中，我们调查了细胞外Ca2+在单羟基胆汁酸牛磺石胆酸诱导的分离大鼠肝细胞胞质Ca+浓度升高过程中可能发挥的作用。结果表明：(a) 在1.2 mM Ca2+或6 μM Ca2+存在的情况下孵育的肝细胞中，胆汁酸可促进胞质Ca+浓度呈相同的剂量依赖性增加（在23 μM时达到半数最大效应）；(b) 在高Ca2+和低Ca2+培养基中，牛磺石胆酸分别能够使Ca2(+)-依赖性糖原磷酸化酶a激活6.3倍和6.0倍；(c) [14C]牛磺石胆酸内流不受细胞外Ca2+的影响，45Ca2+内流也不会因牛磺石胆酸而改变。这些结果表明，牛磺石胆酸对细胞Ca2+的作用不需要细胞外Ca2+，这与单羟基胆汁酸主要从肝脏内质网释放Ca2+的观点一致。
