新型钾通道开放剂QO-58对SD大鼠离体小动脉血管张力的影响及机制

Effect of novel potassium channel opener QO-58 on constrictions of human intrrapulmonary arteries ex vivo and its mechanisms

目的 观察离体状态下不同浓度的新型钾通道开放剂（QO-58）对SD大鼠冠状小动脉血管张力、舒张能力的影响,并探究QO-58对于加强血管舒张功能的可能作用机制.方法 显微镜下离体分离20只SD大鼠的冠状小动脉20根,直径1.0-1.5mm,将每根动脉制成血管环10条,每条长1.8-2.0mm,并作如下实验：（1）每只大鼠取6条内皮完整血管环作平行实验,加入A2受体激动剂（U46619）、60mmol/L高钾溶液、内皮素-1（ET-1）处理后产生均持续性收缩,记录最大收缩幅度100%,在此基础上给予不同浓度的QO-58作对比试验,分为实验1组（10μmol/L）、实验2组（20μmol/L）、实验3组（50μmol/L）、实验4组（100μmol/L）、实验5组（500μmol/L）,并另取1条离体冠状小动脉给予二甲基亚砜（DMSO）作对照组,对比各组小动脉血管环的舒张水平（血管张力）指标;（2）另取每只大鼠4条内皮完整血管环,预收缩处理后,取舒张最为明显的一组的用药浓度为实验浓度,每只取4条血管环作对比试验,A组血管环在给予QO-58前加入eNOS抑制剂（L-NAME）孵育30min,B组用药前不予处理,对比A、B组血管环的血管舒张水平;C组血管环在给予QO-58前去内皮,D组为内皮完整血管环,对比C、D组血管环的血管舒张水平,探究QO-58舒张作用机制.结果 （1）SD大鼠的离体冠状小动脉的50%舒张效应血管张力指数（PD2）、最大舒张率（Emax）值均首先随着加入QO-58的浓度的升高而增加,50μmol/L达到峰值,随后逐渐降低,对照组血管环则均无明显舒张作用,其中实验3组的PD2为3.92±0.13、Emax为（99.78±0.65）%,均为最高、舒张效果最为明显（F=2.927,P=0.013）;（2）关于舒张机制的研究结果显示,A组的PD2、Emax均显著高于B组（P=0.000）;而C、D组血管环的PD2、Emax则比较差异无统计学意义（C组比D组,PD2：P=0.845,Emax,P=0.715）.结论 新型钾通道开放剂（QO-58）对于SD大鼠离体冠状小动脉血管具有良好的舒张作用,且呈浓度依赖性,但浓度过大则舒张作用逐渐减弱,QO-58的血管舒张作用机制无内皮依赖性,但QO-58可能有助于促进NO释放进而达到扩张血管平滑肌、改善血管张力的作用,具有临床应用价值.

Objective To study the effect of novel potassium channel opener QO-58 on constrictions of human intrrapulmonary arteries ex vivo and its probable mechanisms.Methods Under a microscope in vitro separation of 20 SD rats coronary artery 20 small,1-1.5 mm in diameter,make every artery vascular ring 10,each 1.8 2.0 mm long,and the following experiments： （1）Each rat only six complete endothelial vascular ring for parallel experiment,add A2 agonists （U46619）,high tendency of 60L potassium solution,endothelin 1 （ET1） after processing to produce sustained contraction,the biggest contraction rate of 100%,on the basis of given different concentrations of QO-58 comparison test,divided into the experimental group 1 （10 μmol/L）,experiment group 2 （20 μmol/L）,experiment 3 groups （50 μmol/L）,experiment 4 groups （100 μmol/L）,experiment 5 groups （500 μmol/L）,and another 1 in vitro small coronary arteries give DMSO as the control group,contrast groups of small artery diastolic level （vascular tension） ring;（2） Take each other rats four endothelial vascular ring,complete shrinkage after processing,take a set of drug concentration of diastolic most obvious experiment concentration,each taking four loop comparison test,group A vascular ring before give QO-58 join L-NAME （eNOS inhibitors） incubation for 30 min,group B will not be processing before using this drug,compared to A,B group of vascular ring vasodilation level;Group C loop in the endothelium,before give QO-58 group D for endothelial vascular ring,complete contrast C,group D vascular ring vasodilatation,explore QO-58 diastolic function mechanism.Results （1）SD rats in vitro small coronary arteries of PD2 （50% relaxation effect vascular tension index）,Emax （maximum diastolic rate） are as the first to join QO-increases with the rising of concentration of 58,50 mu mol/L peak,then gradually reduced,the control loop is no apparent diastolic function,and the PD2 （3.92±0.13）and Emax [（99.78±0.65）%] for Experiment Group 3 were the highest,diastole effect was most pronounced （F=2.927,P=0.013）;（2）Research on mechanism of diastolic,according to the results of PD2,Emax of group A were significantly higher than that of group B （P=0.000）;And group C,group D vascular ring PD2,Emax is more difference has no statistical significance （group C vs.group D,PD2： P=0.845,Emax,P=0.715）.Conclusion Noble potassium channels open agent （QO-58） in SD rat in vitro small coronary arteries good diastolic function,and the concentration dependence,but excessive concentration of diastolic function weakened,QO-58 without endothelium dependent vasodilatation function mechanism,but QO-58 May help promote the NO release and to expand the role of vascular smooth muscle,improve vascular tension,have clinical application value.