Abstract
Cell volume regulation is a fundamental function for living cells. In hypertonic situations, the intracellular osmolality is increased by accumulation of osmolytes and water is driven into the cell for recovery of original cell volume. In some cases, cells with chronic exposure to hypertonic media ultimately swell over their initial volume (rebound cell swelling: RCS). The RCS was considered to cause edema, however mechanisms of this phenomenon were not well known. In the present study, to elucidate molecular mechanisms of RCS, we observed cell volume and morphological change of C6 glia cells incubated in hypertonic media. Cells were cultured up to 50% confluence in normal media and exposed to the hypertonic media for 48 h, which were made by adding sucrose and urea directly to normal media. When cells were acclimated to the hypertonic sucrose and urea media, the cell volume exceeded its initial volume. The RCS in the sucrose medium was accompanied by intracellular vacuolation, whereas cells in the urea medium did not form vacuoles in the cytoplasm. In hypertonic sucrose media, cells had a rounded shape, while cells in the urea medium exhibited a flatter shape and an irregular surface with flutter edge. These results suggest that a feature of RCS is dependent on kinds of osmolytes, and that a disruption of cellular metabolism and formation of cytoskeletons are caused by extracellular hyperosmolality. Supported by JSPS 15659052 (YM), 15590189 (NN), 15790120 (HM), MHLW 15A-1. [Jpn J Physiol 54 Suppl:S77 (2004)]
