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目的腹部血流在维持消化系统和循环系统的稳态中发挥重要作用,其中肠系膜动脉阻力血管起关键作用。我们应用膜片箝技术,研究Wistar大鼠肠系膜动脉阻力血管平滑肌钙离子单通道特性及硝普钠对其影响。方法从Wistar大鼠肠系膜动脉分支阻力血管分离新鲜平滑肌细胞。以100mmol·LBa~为载流子应用细胞贴附式(cell attached)膜片箝方法,记录细胞膜钙离子单通道电流(I_(Ca))。箝制电压为-70mV,检测电压分别为10mV和+20mV。结果此(I_(Ca))的平均电流幅值(A)开放时和开放概率(Po)分别为(平均数标准差10):在检测电压10mV时;A(1.16±0.28)pA,(1.7±0.82)ms和Po(0.16±0.09);检测电压+20mV时:A(1.14±0.34)pA,(1.5+0.76)ms和Po(0.20±0.10)。Bay K 8644(L型钙通道的激动剂)可激活I_(Ca)将一氧化氮(NO)供体硝普钠(10~9mol·L~1)加入细胞浴液,数秒之内I_(Ca)活动即被灭活或抑制,并于数分钟内恢复,有时在对I_(Ca)的抑制作用之后可记录到兴奋作用,此时如再次应用同样剂量的硝普钠I_(Ca)活动可再被抑制。结论 NO可灭活肠系膜动脉A_4A_5段阻力血管平滑肌细胞膜I_(Ca)随后所产生的兴奋作用,可能由NO的代谢产物所致,这是首次在同一膜片记录到NO双向和的报道。
Objective Abdominal blood flow plays an important role in maintaining the homeostasis of the digestive and circulatory systems, in which the resistance mesenteric artery plays a key role. We used patch clamp technique to study the single-channel calcium channel characteristics of mesenteric artery resistance vascular smooth muscle in Wistar rats and the effects of sodium nitroprusside on it. Methods Fresh smooth muscle cells were isolated from resistance vessels in the mesenteric artery of Wistar rats. The cell membrane calcium ion single channel current (I_ (Ca)) was recorded using cell attached patch clamp method with 100 mmol·L Ba ~ as carrier. Clamping voltage is -70mV, the detection voltage is 10mV and +20 mV. Results The average current amplitude (A) at open time and open probability (Po) were (mean standard deviation 10) at the detection voltage of 10 mV; A (1.16 ± 0.28) pA, ± 0.82) ms and Po (0.16 ± 0.09), respectively; A (1.14 ± 0.34) pA, (1.5 + 0.76) ms and Po (0.20 ± 0.10) at the detection voltage of +20 mV. Bay K 8644 (L-type calcium channel agonist) can activate I_ (Ca) Nitric oxide (NO) donor sodium nitroprusside (10 ~ 9mol·L ~ 1) added to the cell bath within a few seconds I_ (Ca ) Activity is inactivated or inhibited, and recovered in a few minutes, and sometimes I_ (Ca) inhibition can be recorded after the excitement, this time if the same dose of sodium nitroprusside I_ (Ca) activity can be Restrained. CONCLUSION NO-induced inactivation of I_ (Ca) in the vascular smooth muscle cell membrane of A_4A_5 segment of mesenteric artery may be caused by NO metabolites. This is the first time that NO bi-directional summation has been reported on the same membrane.