Nickel inhibition of the osmotic-sensitive ionic cellular channels

The effects of nickel on cell volume regulation were studied in isolated proximal renal tubules from Carassius auratus (goldfish). Variations in cell volume were measured as changes in the external tubular diameters as a function of time of exposure to NiCl2 (Ni(II] in both isotonic and hypotonic solutions. Renal tubules were first incubated in isotonic fish Ringer's solution (290 mOsm) with and without 0.05, 0.10, 0.50, and 1.00 mmol/L Ni(II) for three minutes. After this period, the bath solution was rapidly changed to hypotonic NaCl-poor Ringer's solution (110 mOsm). Renal cells exposed to Ni(II) (0.05 to 1.00 mmol/per L) did not undergo cell swelling in isotonic solutions. However, in a dose related manner, Ni(II) inhibited the volume regulatory process of cells exposed to hypotonic solutions. The effect of Ni(II) on cell volume regulation was specific to the osmoregulatory phase; that is, while there was no inhibition of the hypotonically-induced cell swelling (osmometric phase), there was a significant dose-dependent inhibition of the cellular volume regulatory decrease that follows (osmoregulatory phase). It is postulated by us that nickel inhibition of the osmoregulatory process is secondary to an inhibition of the osmotic sensitive ionic channels.