血管内皮源性舒张因子对血管平滑肌钙激活钾通道活性影响的对比研究

Comparison of the effects of EDRF on calcium-activated potassium channels of mesenteric artery smooth muscle between patients with essential hypertension and normotensive patients

目的 探讨血管内皮源性舒张因子对高血压及非高血压患者血管平滑肌钙激活钾通道 (KCa)活性的影响。方法 选择 2 0 0 1～ 2 0 0 3年泸州医学院附属医院 2 1例高血压病患者及 18例非高血压者 ,切取肠系膜动脉小分支节段用酶消化法获取血管平滑肌细胞 ,以膜片钳技术检测KCa通道的活性 ,通过Pclamp专用软件实时采样记录其平均开放时间 (To)、平均关闭时间 (Tc)、平均开放概率 (Po)等。采用硝酸还原法测定血浆一氧化氮(NO)含量 ,用比色法测定血浆一氧化氮合成酶 (NOS)含量。结果 (1)两组对象KCa通道活性变化 :于细胞内面向外膜片下 ,高血压病组与非高血压组比较 ,前者KCa通道Po增加 ,Tc延长、To缩短。在浴液中分别加入Ca2 +后 ,两组KCa通道均被明显激活 ,与加Ca2 + 前比较 ,非高血压组Po的增加显著高于高血压病组 (P <0 0 1) ,说明高血压病组KCa通道对Ca2 + 的敏感性显著低于血压正常组。 (2 )高血压患者血浆NO、NOS较非高血压组显著降低。 (3)非高血压组血浆NO与KCa通道Po、To呈正相关 ,与Tc呈负相关。高血压病组NO与KCa通道Po、To、Tc的相关性明显弱于非高血压组。结论 高血压病患者肠系膜动脉平滑肌KCa通道活性明显增高 ,血管内皮源性舒张因子对非高血压及高血压病患者血管平滑肌KCa通道均有激活作?

Objective To study the effects of Nitric oxide(NO),Nitric oxide synthases (NOS)on calcium-activated potassium channels (KCa) of mesenteric artery smooth muscle(SMC)between patients with essential hypertension (EH) and normotensive patients.Methods (1)Mesenteric artery branch from 21 EH and 18 normotensive patients respectively was digested by enzyme.Patch clamp technique was used to pull cell-attached and inside-out patches on mesenteric artery SMC from EH.The signal channel open number probability (Po),open dwell-time(To) and close dwell- time(Tc),were recorded.(2)The levels of plasma NO?NOS were measured by colorimetry analysis method.(3)The analysis of linear correlation was performed to estimate the relationship between the levels of plasma NO and Po?To?Tc of KCa of mesenteric artery SMC in the subjects of the two groups.Results (1)Compared to that of normotensive patients,the activities of KCa channels of patients with EH was higher.After adding Ca 2+ to cytoplasm,the Po of KCa channels in normotensive patients increased significantly.But there were few changes in EH group.(2)The levels of plasma NO?NOS were lower in EH group than in control group.(3)Linear correlation analysis showed that the levels of plasma NO were correlated positively with Po?To in normotensive patients,wherese the positive correlation were decreased in EH group.Conclusion The activities of KCa channels of patients with EH increase significantly.but the sensitivity to Ca 2+ decreased.NO?NOS may stimulate the KCa channels of normotensive and EH patients,but they may not be main factors in EH patients.