Effects of potassium channel blockers on the proliferation ofrat bronchial smooth muscle cells

AimTo investigate the effects of blockers of the three kinds of potassium channels: voltage-dependent K⁺ channel(K_V), calcium-activated K⁺ channel(K_Ca) and ATP-sensitive K⁺ channel(K_ATP), on the proliferation of rat bronchial smooth muscle cells (BSMCs). MethodsThe effects of three kinds of potassium channel blockers on the proliferation of BSMCs were detected by MTT method, immunocytochemistry staining and flow-cytometry. Their effects on the dynamic changes of Ca²⁺ concentration in BSMCs were investigated by the fluorophotometry of Fura-2/AM. ResultsThe K_V blocker 4-aminopyridine (4-AP) was shown to significantly increase the expression of proliferating cell nucleus antigen in cultured rat BSMCs (P<0.01), but the K_Ca blocker tetraethylammonium (TEA) and K_ATP blocker glibenclamide(Glib) did not show such effect (P>0.05). 4-AP was found to significantly increase the optical density value of the cultured BSMCs (P<0.01) by MTT method and the numbers of S+G₂M BSMCs(P<0.05) by flow-cytometry. TEA and Glib did not show such effects. 4-AP significantly increased the Ca²⁺ concentration in cultured BSMCs(P<0.01). TEA and Glib did not show such effects. ConclusionThis result suggests that inhibition of K_V activity can increase intracellular Ca²⁺ and proliferation of rat BSMCs, but inhibition of K_Ca and K_ATP showed no effect.