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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 investigate the effect of endothelium-derived relaxing factor on the activity of calcium-activated potassium channel (KCa) in hypertensive and nonhypertensive patients. Methods 21 cases of hypertensive patients and 18 cases of non-hypertensive patients were selected from Affiliated Hospital of Luzhou Medical College from 2001 to 2003. The small mesenteric artery segments of the mesenteric artery were excised and the vascular smooth muscle cells were obtained by enzyme digestion. Patch-clamp technique was used to detect the activity of KCa channel. The average open time (To), average off time (Tc), average open probability (Po) and so on were recorded by real-time sampling with Pclamp software. Plasma nitric oxide (NO) content was determined by nitric acid reduction method, and plasma nitric oxide synthase (NOS) content was determined by colorimetry. Results (1) The changes of KCa channel activity in both groups were observed under the outer membrane in the cells. Compared with the non-hypertension group, the former increased the Po of KCa channel, prolonged Tc and shortened To. After adding Ca2 + into the bath respectively, both KCa channels were obviously activated. Compared with the pre-Ca2 + treatment, the increase of Po in non-hypertension group was significantly higher than that in hypertension group (P <0.01) The sensitivity of KCa channel to Ca2 + in blood pressure sickness group was significantly lower than that in normal blood pressure group. (2) Plasma NO and NOS in hypertensive patients were significantly lower than those in non-hypertensive patients. (3) There was a positive correlation between plasma NO and KCa channels Po, To in non-hypertension group and a negative correlation with Tc. The correlation between NO and KCa channel Po, To, Tc in hypertensive patients was significantly weaker than that in non-hypertensive patients. Conclusions The activity of KCa channel of mesenteric artery smooth muscle in patients with essential hypertension is significantly increased. Endothelium-derived relaxing factor is activated in the vascular smooth muscle cells of non-hypertensive and hypertensive patients.