Intracellular calcium and pH alterations induced by tri-n-butyltin chloride in isolated rainbow trout hepatocytes: a flow cytometric analysis.
The effects of tri-n-butyltin chloride (TBT) on ionic homeostasis on isolated trout hepatocytes were investigated by flow cytometry (FCM), using the Ca(2+)-sensitive and pH-sensitive fluorescent probes Indo-1 and SNARF-1, respectively. Cell viability was monitored concurrently. Treatment of hepatocytes with 1 and 5 microM TBT caused a rapid and sustained elevation of cytosolic free Ca2+ concentration [Ca2+]i and an important cytoplasmic acidification. These changes were dependent upon TBT concentration and were maintained over 60 min, the maximum exposure period investigated. At 0.5 microM TBT, there was a slight but not significant increase in [Ca2+]i and a significant reduction in intracellular pH (pHi) only after 60 min of exposure. A rise in [Ca2+]i and cytoplasmic acidification were observed before loss of viability was detectable. Experiments carried out in Ca(2+)-free medium suggest that TBT mainly mobilizes Ca2+ from intracellular stores in trout hepatocytes. The cytoplasmic acidification following TBT exposure seems to be caused by the combination of intracellular Ca2+ mobilization and by direct action of TBT. The present results suggest that ionic homeostasis perturbations could be early events in the mechanism of cell injury by TBT.
Department of Biophysics, Norwegian Radium Hospital, Oslo.
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Denizeau
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002469:Cell Separation; D002470:Cell Survival; D003600:Cytosol / Q000378:metabolism; D004787:Environmental Pollution; D005434:Flow Cytometry; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D014220:Trialkyltin Compounds / Q000494:pharmacology*
D014220:Trialkyltin Compounds; C011559:tributyltin; D002118:Calcium