fm1-43 and chelerythrine

The effect of hyposmotic shock on exocytosis was examined in isolated hepatocytes of turbot, a marine flatfish, using the molecular probe FM1-43. Sudden exposure to a reduced osmolality caused an increase in cell exocytic activity related to the osmotic gradient between intra- and extracellular fluids. Cytoskeletal microtubules could contribute to this hyposmotic-induced exocytosis since colchicine inhibited the process. Protein kinase C, phosphatidylinositol-3 kinase, phospholipases A2, C and D could constitute key enzymes in the mechanism since their inhibition by specific agents altered the hyposmotic-induced exocytic activity. Moreover, arachidonic acid and derivates from the 5-lipoxygenase pathway as well as calcium could participate in the process. As regulatory volume decrease (RVD) exhibited by turbot hepatocytes following hyposmotic stimulation involves similar features, a potential role of exocytosis in volume regulation is suggested. In particular, exocytosis could serve RVD by contributing to ATP release since this latter process similarly appeared to be phospholipase D-dependent and related to the osmotic gradient. This study provides the first evidence of a volume-sensitive exocytosis that could aim at volume constancy in a marine teleost fish cell type.

Topics: 1-Butanol; Alkaloids; Androstadienes; Animals; Benzophenanthridines; Cell Membrane; Colchicine; Cytochalasin B; Cytoskeleton; Estrenes; Exocytosis; Flatfishes; Fluorescent Dyes; Hepatocytes; Indomethacin; Ionomycin; Isoquinolines; Masoprocol; Osmotic Pressure; Phenanthridines; Pyridinium Compounds; Pyrrolidinones; Quaternary Ammonium Compounds; Quinacrine; Signal Transduction; Sulfonamides; Thapsigargin; Wortmannin