Open AccessBile acids mobilise internal Ca 2+ independently of external Ca 2+ in rat hepatocytes
Author(s) -
COMBETTES Laurent,
BERTHON Brigitte,
DOUCET Edith,
ERLINGER Serge,
CLARET Michel
Publication year - 1990
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1990.tb15617.x
Subject(s) - cytosol , endoplasmic reticulum , extracellular , bone canaliculus , chemistry , calcium , intracellular , biochemistry , endocrinology , medicine , biology , microbiology and biotechnology , enzyme , anatomy , organic chemistry
In the present study, we investigated the possible role of external Ca 2+ 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 μM) in hepatocytes incubated in the presence of 1.2 mM Ca 2+ or 6 μM Ca 2+ ; (b) taurolithocholate is able to activate the Ca 2+ ‐dependent glycogen phosphorylase a by 6.3‐fold and 6.0‐fold in high and low Ca 2+ media, respectively; (c) [ 14 C]taurolithocholate influx is not affected by external Ca 2+ , and 45 Ca 2+ influx is not altered by taurolithocholate. These results establish that the effects of taurolithocholate on cell Ca 2+ do not require extracellular Ca 2+ and are consistent with the view that monohydroxy bile acids primarily release Ca 2+ from the endoplasmic reticulum in the liver.