AJP - Gastrointestinal and Liver Physiology, Vol 258, Issue 2 299-G307, Copyright © 1990 by American Physiological Society

ARTICLES

Effects of osmotic stresses on isolated rat hepatocytes. II. Modulation of intracellular pH

D. Gleeson, J. G. Corasanti and J. L. Boyer
Department of Medicine and Liver Center, Yale University School of Medicine, New Haven, Connecticut 06510.

To assess the roles of acid-base transport systems in cell volume regulation in rat hepatocytes, intracellular pH (pHi) was measured in subconfluent monolayers loaded with 2'-7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) after exposure to hypotonic and relative hypertonic media, interventions that stimulate regulatory volume decrease (RVD) and increase (RVI), respectively. During RVD, pHi decreased from 6.98 +/- 0.11 to 6.85 +/- 0.08 in the absence of HCO3- and from 7.26 +/- 0.10 to 7.19 +/- 0.06 in its presence. Omission of Na+ or addition of 1 mM amiloride prevented the decline in pHi. Acute withdrawal or replacement of Na+ in hypotonic medium resulted in a slower rate of fall or recovery in pHi, respectively, than when the same maneuvers were carried out in isotonic medium. In contrast, during RVI, pHi increased from 6.86 +/- 0.11 to 7.15 +/- 0.15 in the absence of HCO3-, a rise in pHi that was also completely abolished by Na+ removal or by 1 mM amiloride. In the presence of HCO3-, the rise in pHi was less marked than in its absence, although net acid efflux was greater because of a greater intracellular buffering capacity. Cl- removal in the presence of HCO3- had no effect on the change in pHi during either RVD or RVI. Perfusion with 0.5 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) during RVD lowered pHi further and accentuated the subsequent pHi rise seen after the return to isotonic medium. These data suggest that Na(+)-H+ exchange in rat hepatocytes is downregulated during RVD and activated during RVI. Cl(-)-HCO3- exchange does not appear to be involved in hepatocyte volume regulation.

This article has been cited by other articles:

				S. L'Hoste, H. Barriere, R. Belfodil, I. Rubera, C. Duranton, M. Tauc, C. Poujeol, J. Barhanin, and P. Poujeol Extracellular pH alkalinization by Cl-/HCO3- exchanger is crucial for TASK2 activation by hypotonic shock in proximal cell lines from mouse kidney Am J Physiol Renal Physiol, February 1, 2007; 292(2): F628 - F638. [Abstract] [Full Text] [PDF]

				F. Wehner and H. Tinel Uptake of bromosulfophthalein via SO2-4/OH- exchange increases the K+ conductance of rat hepatocytes Am J Physiol Gastrointest Liver Physiol, June 1, 1999; 276(6): G1380 - G1390. [Abstract] [Full Text] [PDF]

				S. Kaiser Cell volume regulates liver phosphoenolpyruvate carboxykinase and fructose-1,6-bisphosphatase genes Am J Physiol Gastrointest Liver Physiol, March 1, 1998; 274(3): G509 - G517. [Abstract] [Full Text] [PDF]

				F. LANG, G. L. BUSCH, M. RITTER, H. VOLKL, S. WALDEGGER, E. GULBINS, and D. HAUSSINGER Functional Significance of Cell Volume Regulatory Mechanisms Physiol Rev, January 1, 1998; 78(1): 247 - 306. [Abstract] [Full Text] [PDF]

				A. Kramer-Guth, G. L. Busch, N. K. Kaba, S. Schwedler, C. Wanner, and F. Lang Effect of osmolarity on LDL binding and internalization in hepatocytes Am J Physiol Cell Physiol, October 1, 1997; 273(4): C1409 - C1415. [Abstract] [Full Text] [PDF]