|
||
The Journal of General Physiology, Vol 105, 507-535, Copyright © 1995 by The Rockefeller University Press
ARTICLES |
F Wehner, H Sauer and RK Kinne
Max-Planck-Institut fur molekular Physiologie, Abteilung Epithelphysiologie, Dortmund, Germany.
We studied the ionic mechanisms underlying the regulatory volume increase of rat hepatocytes in primary culture by use of confocal laser scanning microscopy, conventional and ion-sensitive microelectrodes, cable analysis, microfluorometry, and measurements of 86Rb+ uptake. Increasing osmolarity from 300 to 400 mosm/liter by addition of sucrose decreased cell volumes to 88.6% within 1 min; thereafter, cell volumes increased to 94.1% of control within 10 min, equivalent to a regulatory volume increase (RVI) by 44.5%. This RVI was paralleled by a decrease in cell input resistance and in specific cell membrane resistance to 88 and 60%, respectively. Ion substitution experiments (high K+, low Na+, low Cl-) revealed that these membrane effects are due to an increase in hepatocyte Na+ conductance. During RVI, ouabain-sensitive 86Rb+ uptake was augmented to 141% of control, and cell Na+ and cell K+ increased to 148 and 180%, respectively. The RVI, the increases in Na+ conductance and cell Na+, as well as the activation of Na+/K(+)-ATPase were completely blocked by 10(-5) mol/liter amiloride. At this concentration, amiloride had no effect on osmotically induced cell alkalinization via Na+/H+ exchange. When osmolarity was increased from 220 to 300 mosm/liter (by readdition of sucrose after a preperiod of 15 min in which the cells underwent a regulatory volume decrease, RVD) cell volumes initially decreased to 81.5%; thereafter cell volumes increased to 90.8% of control. This post-RVD-RVI of 55.0% is also mediated by an increase in Na+ conductance. We conclude that rat hepatocytes in confluent primary culture are capable of RVI as well as of post-RVD-RVI. In this system, hypertonic stress leads to a considerable increase in cell membrane Na+ conductance. In concert with conductive Na+ influx, cell K+ is then increased via activation of Na+/K(+)-ATPase. An additional role of Na+/H+ exchange in the volume regulation of rat hepatocytes remains to be defined.
This article has been cited by other articles:
![]() |
K. S. Lang, S. Myssina, P. A. Lang, V. Tanneur, D. S. Kempe, A. F. Mack, S. M. Huber, T. Wieder, F. Lang, and C. Duranton Inhibition of erythrocyte phosphatidylserine exposure by urea and Cl- Am J Physiol Renal Physiol, June 1, 2004; 286(6): F1046 - F1053. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Myssina, S. M. Huber, C. Birka, P. A. Lang, K. S. Lang, B. Friedrich, T. Risler, T. Wieder, and F. Lang Inhibition of Erythrocyte Cation Channels by Erythropoietin J. Am. Soc. Nephrol., November 1, 2003; 14(11): 2750 - 2757. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. J. Rozansky, J. Wang, N. Doan, T. Purdy, T. Faulk, A. Bhargava, K. Dawson, and D. Pearce Hypotonic induction of SGK1 and Na+ transport in A6 cells Am J Physiol Renal Physiol, July 1, 2002; 283(1): F105 - F113. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. Lyall, G. L. Heck, J. A. DeSimone, and G. M. Feldman Effects of osmolarity on taste receptor cell size and function Am J Physiol Cell Physiol, October 1, 1999; 277(4): C800 - C813. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. J. Ahn, D. R. Brooker, F. Kosari, B. J. Harte, J. Li, S. A. Mackler, and T. R. Kleyman Cloning and functional expression of the mouse epithelial sodium channel Am J Physiol Renal Physiol, July 1, 1999; 277(1): F121 - F129. [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] |
||||
![]() |
W. C. O'Neill Physiological significance of volume-regulatory transporters Am J Physiol Cell Physiol, May 1, 1999; 276(5): C995 - C1011. [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] |
||||
|
|