VOLUME REGULATION IN RAT PHEOCHROMOCYTOMA CULTURED-CELLS SUBMITTED TO HYPOOSMOTIC CONDITIONS

The mechanisms at work in cell volume regulation have been studied in PC12 cultured cells. Results show, for the first time to our knowledge, that the volume readjustment process occurring after application of a hypoosmotic saline is sensitive to amiloride, IBMX and forskoline. The process is also inhibited by quinine hydrochloride and trifluoperazine. Volume readjustment is concomitant with a decrease in K+ and Cl- intracellular levels. The decrease in K+ level can be related to an assymetrical change in the fluxes in and out of the ion as shown by flux kinetics studies using Rb-86. These results are interpreted considering that the control of the activity of the ion channel pathways associated with volume readjustment in PC12 cells may implicate the Ca2+-calmodulin - cAMP system.