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目的 探讨不同浓度二十碳五烯酸(EPA)对糖尿病大鼠冠状动脉的舒张作用及其机制.方法 40只SD大鼠随机分为正常组和糖尿病组,分离冠状动脉.采用微血管张力测定技术评估不同浓度(0.1、1、3、10、30、100μmol/L)EPA对正常和糖尿病大鼠冠状动脉的舒张作用并观察孵育(100nmol/L)大电导钙激活钾通道(BK通道)特异性阻滞剂伊比蝎毒素(IBTX)后血管张力的变化;酶消化法分离正常和糖尿病大鼠冠状动脉平滑肌细胞并采用单通道膜片钳技术记录灌流不同浓度(0、10、30、100、300、1000pmol/L)EPA时BK通道开放概率的变化;采用蛋白印迹技术测定正常和糖尿病大鼠冠状动脉BK通道亚单位蛋白表达.结果 EPA对正常组和糖尿病组大鼠冠状动脉舒张的比例随浓度升高而增加,孵育IBTX后舒张作用明显减弱;EPA对正常组和糖尿病组大鼠冠状动脉平滑肌细胞BK通道的激活随浓度升高而增强,且与正常组比较,EPA对糖尿病组大鼠冠状动脉的舒张作用及BK通道的激活作用较弱.两组大鼠冠状动脉BK通道蛋白α亚单位表达无差异,但糖尿病大鼠冠状动脉BK通道蛋白β1亚单位表达明显低于正常组(0.4247±0.0362vs0.8923±0.0535,n=6,P<0.05).结论 EPA对糖尿病冠状动脉具有舒张作用,其机制与激活BK通道有关,糖尿病时BK通道β1亚单位表达减少,EPA对BK通道的激活作用减弱.
Objective To investigate the effects of different concentrations of eicosapentaenoic acid (EPA) on coronary vasodilatation in diabetic rats and its mechanism.Methods 40 SD rats were randomly divided into normal group and diabetic group, and the coronary arteries were isolated.Using the microvascular tension measurement The effects of EPA at different concentrations (0.1, 1, 3, 10, 30, 100μmol / L) on coronary vasodilatation in normal and diabetic rats were evaluated and the specificity of incubation with 100nmol / L large-conductance calcium-activated potassium channel The changes of vascular tone after blocker IBPX were detected by enzyme-linked immunosorbent assay (ELISA). Smooth muscle cells of normal and diabetic rats were isolated by enzymatic digestion and single-channel patch-clamp technique was used to record the changes of vascular tension at different concentrations (0, 10, 30, 100, , 1000 pmol / L) EPA, and the protein expression of BK channel subunit of coronary artery in normal and diabetic rats was detected by Western blotting.Results The ratio of EPA to coronary diastolic in normal and diabetic rats increased with concentration Increased and then increased, and the vasodilation obviously decreased after IBTX incubation. The activation of BK channel in coronary artery smooth muscle cells of normal and diabetic rats increased with the increase of EPA, Compared with the control group, the diastolic function of the coronary artery and the activation of the BK channel in diabetic rats were weaker than those in the diabetic rats.No difference was found in the expression of BK channel protein α subunit in the coronary artery of diabetic rats, but there was no difference in the BK channel protein β1 subunit (0.4247 ± 0.0362vs0.8923 ± 0.0535, n = 6, P <0.05) .Conclusion EPA has a diastolic effect on diabetic coronary arteries, the mechanism of which is related to the activation of BK channels, and the expression of BK channel β1 subunit Reduced expression of EPA, BK pathway activation weakened.