Single rat hepatocytes show repetitive oscillations in cytosolic free Ca2+ concentration ([Ca2+]i) when stimulated by agonists acting through the phosphoinositide signalling pathway. We have studied the effect of a natural bile acid, taurolithocholate (TLC), and its sulphated form, taurolithocholate 3-sulphate (TLC-S), on [Ca2+]i in single isolated rat hepatocytes. Although these bile acids are believed to act through a common mechanism to permeabilize the intracellular Ca2+ pool, the [Ca2+]i responses induced by the two compounds were different. Whereas TLC induced a sustained elevation of [Ca2+]i, TLC-S evoked repetitive [Ca2+]i oscillations. In addition, we show that ryanodine, which blocks the Ca(2+)-induced Ca2+ release (‘CICR’) mechanism, blocked TLC-S-induced oscillations in 50% of hepatocytes, but did not affect the TLC-induced rise in [Ca2+]i.
Taurolithocholate and taurolithocholate 3-sulphate exert different effects on cytosolic free Ca2+ concentration in rat hepatocytes
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I Marrero, A Sanchez-Bueno, P H Cobbold, C J Dixon; Taurolithocholate and taurolithocholate 3-sulphate exert different effects on cytosolic free Ca2+ concentration in rat hepatocytes. Biochem J 1 June 1994; 300 (2): 383–386. doi: https://doi.org/10.1042/bj3000383
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