Altered expression of potassium channel genes in familial hypokalemic periodic paralysis

ABSTRACT

We analyzed the mRNA expression patterns of major potassium channel genes to determine the mechanism of hypokalemia in familial hypokalemic periodic paralysis. We used quantitative RT-PCR to examine the mRNA levels of both inward (KCNJ2, KCNJ6, and KCNJ14) and delayed rectifi er (KCNQ1 and KCNA2) potassium channel genes in skeletal muscle cells from both normal and patient groups, prior to and after exposure to 4 mM and 50 mM potassium buffers. Quantitative RT-PCR analysis revealed no changes in the mRNA levels of these genes in normal and patient cells on exposure to 4 mM potassium buffer. However, after exposure to 50 mM potassium buffer, which was used to induce depolarization, normal cells showed a signifi cant decrease in KCNJ2, KCNJ6, and KCNJ14 expression, but no change in KCNQ1 and KCNA2 expression. In contrast, patient cells showed no change in KCNJ2 and KCNJ6 expression, but an increase in KCNJ14 expression. Furthermore, KCNQ1 and KCNA2 showed decreased expression. We found that the expression levels of both inward and delayed rectifi er potassium channel genes in patient cells differ from those in normal cells. Altered potassium channel gene expression in patient cells may suggest a possible mechanism for hypokalemia in familial hypokalemic periodic paralysis.