槲皮素改善高糖损伤大鼠冠脉肌原性反应的机制研究

Mechanism of quercetin improving rat coronary artery myogenic response under high glucose

目的:通过大鼠冠状动脉(coronary artery,CA)张力测定和全细胞膜片钳记录CA血管平滑肌细胞(vascular smooth muscle cells,VSMC)的电压门控性钾通道(voltage-gated K^+channel,Kv)电流,研究槲皮素改善高糖损伤大鼠CA肌原性反应的机制。方法:从正常SD大鼠急性分离得到CA环,然后分成6组:(1)正常对照组;(2)高糖组;(3)高糖+低剂量(3μmol/L)槲皮素组;(4)高糖+中剂量(10μmol/L)槲皮素组;(5)高糖+高剂量(30μmol/L)槲皮素组;(6)高糖+蛋白激酶C(protein kinase C,PKC)抑制剂C6303+高剂量槲皮素组。利用血管张力测定,检测CA环对血管收缩剂(60 mmol/L KCl和0.1 mmol/L U46619)的反应,并将CA环用60 mmol/L KCl预收缩后,用乙酰胆碱(acetylcholine,ACh;10^(-9)~10^(-5)mol/L)进行舒张,计算ACh引起CA环张力下降幅度与预先收缩的百分比。急性分离得到大鼠CA的VSMC,然后记录Kv电流。结果:与正常対照组相比,高糖组CA环对60mmol/L KCl和0.1 mmol/L U46619的反应明显升高;中、高剂量槲皮素的干预可以使高糖所致CA环对血管收缩剂的反应降低,孵育PKC特异性抑制剂C6303可减弱槲皮素的作用。与正常对照组相比,高糖组大鼠离体CA环对ACh的舒张幅度明显减弱。槲皮素的干预可以改善高糖孵育的大鼠离体CA环对ACh的舒张反应,C6303可以减弱槲皮素的作用。高糖孵育明显抑制CA VSMC的Kv电流,槲皮素干预可以减弱高糖对CA VSMC Kv电流的影响,孵育C6303可减弱槲皮素的作用。结论:槲皮素对高糖损伤大鼠CA肌原性反应具有保护作用,该作用与增大VSMC的Kv电流和激活PKC有关。

AIM：To investigate the mechanism of quercetin improving rat coronary artery myogenic response under high glucose （ HG） by measuring muscle tension of coronary arterial ring and recording voltage -gated K ＋channel （ Kv） current of coronary artery smooth muscle cells by whole cell patch clamp .METHODS：The coronary rings from the normal SD rats were acutely isolated , and then divided into 6 groups：（1） control group;（2） HG group;（3） HG＋low dose （3 μmol/L） of quercetin group;（4） HG＋moderate dose （10 μmol/L） of quercetin group; （5） HG＋high dose （30 μmol/L） of quercetin group;（6） HG＋C6303 （PKC inhibitor） ＋high dose of quercetin group.Determinations of coronary artery response to vasoconstrictor （60 mmol/L KCl or 0.1 mmol/L U46619） or vasodilator （Ach at 10 -9 ~10 -5 mol/L） were performed, and the percentage of coronary ring tension was calculated using the contraction as 100%caused by 60 mmol/L KCl.The rat coronary artery smooth muscle cells were acutely isolated for recording the Kv current using whole cell patch clamp .RESULTS：Compared with control group , the contraction amplitudes to 60 mmol/L KCl or 0.1 mmol/L U46619 were significantly increased under HG incubation .Quercetin intervention concentration-dependently re-duced the coronary artery contraction amplitude .Incubation of PKC specific inhibitor C 6303 attenuated the effect of querce-tin.Compared with control group , the diastolic amplitude to Ach decreased significantly in HG group , and quercetin inter-vention concentration-dependently increased the coronary artery diastolic amplitude .Incubation of PKC specific inhibitor C6303 attenuated the effect of quercetin .Compared with control group , HG incubation inhibited Kv current of coronary ar-tery vascular smooth muscle cells significantly , and quercetin intervention attenuated the inhibitory effect of HG on Kv cur-rent intensity .Incubation of PKC specific inhibitor C 6303 attenuated the effect of quercetin .CONCLUSION： Quercetin has a protective effect on myogenic response of coronary artery under HG and the effects is related to the increase in Kv cur -rent and the activation of PKC in vascular smooth muscle cells .