Membrane Cl- Currents and Liver Cell Proliferation
Document Type
Article
Publication Date
3-20-1998
Description
Hyperpolarization of hepatocyte membrane potential is among the early events during liver regeneration (Wondergem and Harder, J. Cell Physiol. 102:193, 1980). The accompanying changes in membrane ion conductances, however, and their significance for cell proliferation have not been identified. Thus, we used the whole-cell voltage clamp and inside/out membrane patches to identify an outwardly rectifying Cl- current and a corresponding 20-pS Cl- channel at 100 mV in the plasma membrane of a proliferating, non-transformed mouse liver cell line (AML12). Hypotonie stress (from 280 to 210 mOsm) activated an outwardly rectifying whole-cell current, which took 12 m to reach maximum conductance. Gluconate substituted for external Cl- inhibited this activated current. So did addition of either 4,4′-diisothiocyanatostilbene-2,2′-disulfonate (DIDS; 100 μM) at positive membrane voltage, or 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB; 50 μM) at all membrane voltages. Moreover, both DIDS (IC50 =200 μM) and NPPB (IC50 = 50 μM) inhibited cell growth as determined by cell counts over 4 d and by protein accumulation over 2 d. Mitogen-activated protein kinase (MAPK) activity, measured by western blot using an active MAPK antibody (Promega), increased during 30-m serum stimulation compared with 24-h serum starved cells. Treatment with either NPPB (100 μM) or DIDS (250 μM) during the 24-h serum deprivation inhibited serum activation of MAPK. We conclude that membrane Cl- currents, which can be activated by hypotonic stress, are involved in mechanisms controlling liver cell growth.
Citation Information
Wondergem, R.; Gong, W.; Monen, S.; Dooley, S.; Miller, R.; and Suttles, J.. 1998. Membrane Cl- Currents and Liver Cell Proliferation. FASEB Journal. Vol.12(5). ISSN: 0892-6638