Objective To investigate the role of C-type natriuretic peptide receptor (NPR-C) and large-conductance calcium-activated potassium channels ( BKCa ) in brain natriuretic peptide (BNP) induced porcine coronary artery dilation.Methods Porcine coronary artery rings were obtained and treated with BNP (10-6 mol/L), BNP + NPR-C antagonist cANF4-28 (10-6 mol/L) and BNP + BKCa blocker tetraethylammonium (TEA, 1 mmol/L). The vascular tone experiments were observed on 10 vessel segments. BKCa current density was measured by the whole-cell patch clamp technique.Results The maximum diastolic rate was similar between BNP group ( 68.51％ ± 11.50％ ) and cANF4-28 + BNP group (65.67％ ± 11.90％,P ＞ 0.05) while significantly reduced in TEA + BNP group (28.87％ ± 4.55％,all P ＜ 0.05 ).When the holding potential was set at + 60 mY,the BKCa current density of BNP group was (78.48 ±5.86) pA/pF,which was significantly higher than control group [ (53.84 ±4.55) pA/pF,P ＜0.05],which was equally reduced in the TEA group and TEA + BNP group [ (28.80 ± 2.76) pA / pF and (30.60 ± 3.88) pA/pF respectively,all P ＜ 0.05 vs.control group ].Conclusion BNP could relax the porcine coronary arterial smooth muscles by increasing BKca current,and this effect is not mediated by NPR-C.%目的 探讨利钠肽C受体( NPR-C)和大电导钙激活钾通道(BKCa)在B型利钠肽(BNP)舒张猪冠状动脉中的作用.方法 取健康成年家猪冠状动脉,血管张力实验随机分为BNP组、cANF4-28+ BNP组和TEA+ BNP组,每组均含10个血管段,观察BNP对猪冠状动脉的舒张作用及NPR-C阻断剂cANF4-28、BKCa阻断剂四乙铵(TEA)预处理后BNP舒血管效应的变化.全细胞膜片钳实验随机分为对照组、BNP组、TEA组和TEA+ BNP组,观察各种干预措施对BKCa电流密度的影响,每组均含10个细胞数.结果 BNP组血管最大舒张率为(68.51±11.50)％,cANF4-28+ BNP组最大舒张率为(65.67±11.90)％,两组间差异无统计学意义(P＞0.05).TEA+ BNP组最大舒张率为(28.87±4.55)％,低于BNP组,差异有统计学意义(P＜0.05).当钳制电位在+60 mV时,BNP组的电流密度为( 78.48±5.86) pA/pF,高于对照组的电流密度(53.84±4.55) pA/pF,差异有统计学意义(P＜0.05).TEA组和TEA+ BNP组的电流密度分别为(28.80±2.76)pA/pF和(30.60±3.88)pA/pF,两组间差异无统计学意义(P＞0.05),两组的电流密度均低于对照组,差异均有统计学意义(P均＜0.05).结论 BNP能通过激活BKCa对猪冠状脉平滑肌产生舒张作用,NPR-C未参与其中.
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