Taurolithocholate and taurolithocholate 3-sulphate exert different effects on cytosolic free Ca2+ concentration in rat hepatocytes.
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.
Marrero
I
I
Department of Human Anatomy and Cell Biology, University of Liverpool, U.K.
Sanchez-Bueno
A
A
Cobbold
P H
PH
Dixon
C J
CJ
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012433:Ryanodine / Q000494:pharmacology; D013658:Taurolithocholic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology*
C066776:taurolithocholic acid 3-sulfate; D012433:Ryanodine; D013658:Taurolithocholic Acid; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D002118:Calcium