Efflux of protons from acidic vesicles contributes to cytosolic acidification of hepatocytes during ATP depletion

摘要: The objective of this study was to determine the relationship between cytosolic pH and vesicular during ATP depletion. Using digitized video microscopy single, cultured rat hepatocytes, were quantitated by ratio imaging BCECF (2′, 7′ biscarboxyethyl-5, 6-carboxyfluorescein) fluorescence fluoresceindextran fluorescence, respectively. Basal value for 7.26 basal 4.86. During depletion metabolic inhibition with KCN plus iodoacetic acid or antimycin A, decreased 0.71 units 6.55. In separate experiments under identical conditions, increased 1.59 6.45, suggesting that protons leaking from acidic vesicles Fluorescein-dextran remained punctate, indicating rise in due an efflux not loss vesicle integrity. To whether can acidify pH, we used two maneuvers result leakage without significantly decreasing cellular ATP: (a) hypotonic stress K+ free media (b) exposure cells H+ -ATPase inhibitor NBD-Cl. Both NBD-Cl 0.4 6.86 2.0 6.76, resulting near-equilibration pH. Thus intracellular compartments will hepatocytes (pH 6.86), but same degree as 6.55). Calculations based on buffering capacities relative volumes cytosol suggest into may account up 20% decrease anoxia observed hepatocytes. (HEPATOLOGY 1991;14:626–633.)