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KMID : 0613820090190101484
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Journal of Life Science
2009 Volume.19 No. 10 p.1484 ~ p.1488
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Effect of Extracellular Potassium on Delayed Rectifier Potassium Channel Proteins of KCNQ3 and KCNQ5 in Familial Hypokalemic Periodic Paralysis
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Kim Sung-Jo
Kim Dong-hyun
Kim June-Bum
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Abstract
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Familial hypokalemic periodic paralysis (HOKPP) is an autosomal dominant muscle disorder characterized by episodic attacks of muscle weakness with concomitant hypokalemia. Mutations in either a calcium channel gene (CACNA1S) or a sodium channel gene (SCN4A) have been shown to be responsible for this disease. The combination of sarcolemmal depolarization and hypokalemia has been attributed to abnormalities of the potassium conductance governing the resting membrane potential. To understand the pathophysiology of this disorder, we examined both mRNA and protein levels of delayed rectifier potassium channel genes, KCNQ3 and KCNQ5, in skeletal muscle fibers biopsied from patients with HOKPP. Our results showed an increase in the cytoplasmic level of KCNQ3 protein in patients’ cells exposed to 50 mM external concentration of potassium. However, mRNA levels of both channel genes did not show significant change in the same condition. Our results suggest that long term exposure of skeletal muscle cells in HOKPP patients to high extracellular potassium alters the KCNQ3 localization, which could possibly hinder the normal function of this channel protein. These findings may provide an important clue to understanding the molecular mechanism of familial hypokalemic periodic paralysis.
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KEYWORD
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Hypokalemic periodic paralysis, potassium channel, KCNQ3, KCNQ5, delayed rectifier
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