Effects of Iptakalim on intracellular free calcium concentration of cultured rabbit pulmonary arterial smooth muscle cells1

ObjectiveTo explore the effects of Iptakalim on intracellular free calcium concentration and on the proliferation of cultured rabbit pulmonary arterial smooth muscle cells induced by endothelin-1(ET-1) in vitro.MethodsA cell culture model, [3H]-thymidine([3H]-TdR) incorporation test and confocal microscope were used to observe proliferation and intracellular free calcium concentration([Ca2+]i) of rabbit PASMC induced by ET-1 in vitro.ResultsThe value of [3H]-TdR incorporation in ET-1 group was increased 1.468 times higher than that in control group. Iptakalim at the concentration of 10−7mol/L, 10−6 mol/L, 10−5 mol/L lowered [3H]-TdR incorporation by (19.8 ± 4.6)%, (41.2 ± 9.5)%, (54.7 ± 10.1)%, respectively, compared with the value of the cells treated with ET-1(P < 0.01); The intracellular fluorescence intensity of PASMC in ET-1 group was increased from 73.70 ± 10.12 to 143.84 ± 28.23, significantly higher than that in control group(P < 0.01); whereas with Iptakalim, the fluorescence intensity(FI) was only increased from 74.30 ± 10.20 to 86.03 ± 9.82, significantly lower than that in ET-1 group(P < 0.01).ConclusionIptakalim inhibited proliferation of PASMC and decreased intracellular free calcium concentration of cultured rabbit PASMC induced by ET-1.