Kv7在尼古丁致小鼠肺动脉肌张力增强中的作用研究OA

AIM:To investigate the role of Kv7 channels in nicotine-induced enhancement of pul-monary arterial tension in mice.METHODS:Mice were anesthetized,and lung tissues were quickly re-moved and placed in 4℃ Krebs-Henseleit(K-H)buffer.Pulmonary arteries were dissected under a microscope and cut into rings approximately 2 mm in length.Effect of nicotine on isolated pulmonary artery tension under agonist prestimulation:pul-monary artery rings with a basal tension>2 mN were precontracted with norepinephrine(NE)or phenylephrine(PE)to reach a plateau.Different concentrations of nicotine(10-11-10-5 mol/L)were then added,and changes in tension were recorded.The half-maximal effective concentration(EC50)was calculated and used as the optimal intervention concentration for subsequent experiments.Detec-tion of intracellular Ca2+in pulmonary artery smooth muscle cells(PASMCs):fresh PASMCs were isolated from mouse pulmonary arteries using enzy-matic digestion and incubated in Ca2-free HBSS so-lution.Cells were stained with the Ca2+-sensitive flu-orescent probe Fluo-4 AM,stimulated with EC50 nicotine,and fluorescence intensity before and af-ter stimulation was recorded to evaluate changes in intracellular Ca2+concentration.Effect of incuba-tion time on nicotine-induced pulmonary arterial tension:pulmonary artery rings were incubated with EC50 nicotine for 0,6,12,and 24 h,respective-ly,followed by NE or PE stimulation.The contractile responses at different incubation times were com-pared.Effect of nicotine incubation on Kv7 channel function:Pulmonary artery rings were incubated with EC50 nicotine for 24 h,then treated with the Kv7 channel inhibitor XE991(10-8-10-5 mol/L).The induced contractions were recorded to assess Kv7 channel activity.RESULTS:After mild prestimula-tion with NE or PE,nicotine induced concentration-dependent contractions of mouse pulmonary arter-ies(P<0.01),with an EC50 of 10-8 mol/L.Nicotine stimulation at 10-8 mol/L significantly increased in-tracellular Ca2+levels in PASMCs(P<0.01).Nicotine(10-8 mol/L)incubation for 0,6,12,and 24 h pro-gressively enhanced NE-and PE-induced contrac-tions,with the 24 h group showing the most pro-nounced effect(P<0.01),which was selected as the optimal intervention duration.Compared with the control group,nicotine(10-8 mol/L,24 h)incuba-tion significantly attenuated XE991-induced pul-monary artery contraction(P<0.01).CONCLUSION:Nicotine increases pulmonary arterial tension in mice,and the underlying mechanism may be relat-ed to the inhibition of Kv7 channels.