Osmotic Swelling-Induced Changes in Cytosolic Calcium Do Not Affect Regulatory Volume Decrease in Rat Cultured Suspended Cerebellar Astrocytes

摘要: Hyposmotic swelling-induced changes in intracellular Ca 2+ concentration ([Ca ] i ) and their influence on regulatory volume decrease (RVD) were examined rat cultured suspended cerebellar astrocytes. media (50 or 30%) evoked an immediate rise [Ca from 117 nM to a mean peak increase of 386 (50%) 220 (30%), followed by maintained plateau phase. influx through the plasmalemma as well release internal stores contributed this osmosensitive elevation. Omission external addition Cd , Mn Gd 3+ did not reduce RVD, although it was decreased La (0.1-1 mM). Verapamil affect either swelling-evoked RVD. Maneuvers that deplete endoplasmic reticulum (ER) stores, such treatment (in -free medium) with 0.2 μM thapsigargin (Tg), 10 2,5-di-tert-butylhydroquinone, 1 ionomycin, 100 ATP abolished but However, prolonged exposure Tg blocked RVD regardless ER content cytosolic levels. Ryanodine (up μM) caffeine (10 mM) modify BAPTA-acetoxymethyl ester (20 elevation without affecting at higher concentrations BAPTA prevented cell swelling We conclude occurs consequence increased permeability plasma organelle membranes, appears relevant transduction signal for