Ionic determinants of pH of acidic compartments under hypertonic conditions in trout hepatocytes

Abstract

SUMMARY 5 mmol l -1 ). Furthermore, hypertonicity-induced acidification was still noticeable in the presence of SITS. On the other hand, the hypertonicity-induced acidification was significantly reduced in the absence of extracellular Na + or Ca 2+ . However, BAPTA-AM induced an increase in steady-state pH L that was independent of V-ATPase inhibition. Moreover, the BAPTA-induced alkalinization was still apparent after depletion of intracellular Ca 2+ using the Ca 2+ ionophore A23187 in Ca 2+ -free medium. We conclude that pH L of trout hepatocytes is sensitive to hypertonicity and ionic determinants of hypertonicity. Thus, changes in pH L should be considered when studying pH adaptations to hypertonic stress.