ClC-2 chloride channels contribute to HTC cell volume homeostasis

被引:43
作者
Roman, RM
Smith, RL
Feranchak, AP
Clayton, GH
Doctor, RB
Fitz, JG
机构
[1] Univ Colorado, Hlth Sci Ctr, Dept Med, Denver, CO 80206 USA
[2] Univ Colorado, Hlth Sci Ctr, Dept Neurol, Denver, CO 80206 USA
[3] Univ Colorado, Hlth Sci Ctr, Dept Pediat, Denver, CO 80206 USA
[4] Univ Colorado, Hlth Sci Ctr, Dept Cell Biol, Denver, CO 80206 USA
来源
AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY | 2001年 / 280卷 / 03期
关键词
hepatocyte; purinergic receptors; liver;
D O I
10.1152/ajpgi.2001.280.3.G344
中图分类号
R57 [消化系及腹部疾病];
学科分类号
摘要
Membrane Cl- channels play an important role in cell volume homeostasis and regulation of volume-sensitive cell transport and metabolism. Heterologous expression of ClC-2 channel cDNA leads to the appearance of swelling-activated Cl- currents, consistent with a role in cell volume regulation. Since channel properties in heterologous models are potentially modified by cellular background, we evaluated whether endogenous ClC-2 proteins are functionally important in cell volume regulation. As shown by whole cell patch clamp techniques in rat HTC hepatoma cells, cell volume increases stimulated inwardly rectifying Cl- currents when non-ClC-2 currents were blocked by DIDS (100 muM). A cDNA closely homologous with rat brain ClC-2 was isolated from HTC cells; identical sequence was demonstrated for ClC-2 cDNAs in primary rat hepatocytes and cholangiocytes. ClC-2 mRNA and membrane protein expression was demonstrated by in situ hybridization, immunocytochemistry, and Western blot. Intracellular delivery of antibodies to an essential regulatory domain of ClC-2 decreased ClC-2-dependent currents expressed in HEK-293 cells. In HTC cells, the same antibodies prevented activation of endogenous Cl- currents by cell volume increases or exposure to the purinergic receptor agonist ATP and delayed HTC cell volume recovery from swelling. These studies provide further evidence that mammalian ClC-2 channel proteins are functional and suggest that in HTC cells they contribute to physiological changes in membrane Cl- permeability and cell volume homeostasis.
引用
收藏
页码:G344 / G353
页数:10
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