Effects of BK(Ca) and Kir2.1 Channels on Cell Cycling Progression and Migration in Human Cardiac c-kit(+) Progenitor Cells

Our previous study demonstrated that a large-conductance Ca(2+)-activated K(+) current (BK(Ca)), a voltage-gated TTX-sensitive sodium current (I(Na.TTX)), and an inward rectifier K(+) current (I(Kir)) were heterogeneously present in most of human cardiac c-kit(+) progenitor cells. The present study was designed to investigate the effects of these ion channels on cell cycling progression and migration of human cardiac c-kit(+) progenitor cells with approaches of cell proliferation and mobility assays, siRNA, RT-PCR, Western blots, flow cytometry analysis, etc. It was found that inhibition of BK(Ca) with paxilline, but not I(Na.TTX) with tetrodotoxin, decreased both cell proliferation and migration. Inhibition of I(Kir) with Ba(2+) had no effect on cell proliferation, while enhanced cell mobility. Silencing KCa.1.1 reduced cell proliferation by accumulating the cells at G0/G1 phase and decreased cell mobility. Interestingly, silencing Kir2.1 increased the cell migration without affecting cell cycling progression. These results demonstrate the novel information that blockade or silence of BK(Ca) channels, but not I(Na.TTX) channels, decreases cell cycling progression and mobility, whereas inhibition of Kir2.1 channels increases cell mobility without affecting cell cycling progression in human cardiac c-kit(+) progenitor cells.