CAJ | 학술논문

目的评价不同浓度右美托咪定对大鼠肠系膜动脉平滑细胞大电导钙激活钾通道(BKCa)的影响.方法 SD大鼠,雌雄不拘,体重180～220 g,经两步法酶消化分离肠系膜动脉平滑肌细胞.选取10个肠系膜动脉平滑肌细胞,采用单通道内面向外式膜片钳技术进行记录,钳制电压为40 mV,游离钙离子浓度为10-7 mol/L,采用浓度累积法加入右美托咪定,分别于0(基础值)、10-9、10-8、10-7、10-6、10-5 mol/L右美托咪定时记录BKCa开放概率(NPo)、电流幅度(Am)、平均开放时间(To)和平均关闭时间(Tc).结果与基础值比较,10-7、10-6、10-5 mol/L右美托咪定时NPo升高,且呈浓度依赖性,10-9、10-8、10-7、10-6、10-5 mol/L右美托咪定时Tc缩短(P＜0.05或0.01)；与10-9mol/L右美托咪定比较,10-8mol/L右美托咪定时Tc缩短(P＜0.05),不同浓度右美托咪定时Am和To 差异无统计学意义(P＞0.05).结论 10-7、10-6、10-5 mol/L右美托咪定可呈浓度依赖性地激活大鼠肠系膜动脉平滑肌细胞BKCa通道,是其降压作用的机制之一.
목적 평개불동농도우미탁미정대대서장계막동맥평활세포대전도개격활갑통도(BKCa)적영향.방법 SD대서,자웅불구,체중180～220 g,경량보법매소화분리장계막동맥평활기세포.선취10개장계막동맥평활기세포,채용단통도내면향외식막편겸기술진행기록,겸제전압위40 mV,유리개리자농도위10-7 mol/L,채용농도루적법가입우미탁미정,분별우0(기출치)、10-9、10-8、10-7、10-6、10-5 mol/L우미탁미정시기록BKCa개방개솔(NPo)、전류폭도(Am)、평균개방시간(To)화평균관폐시간(Tc).결과 여기출치비교,10-7、10-6、10-5 mol/L우미탁미정시NPo승고,차정농도의뢰성,10-9、10-8、10-7、10-6、10-5 mol/L우미탁미정시Tc축단(P＜0.05혹0.01)；여10-9mol/L우미탁미정비교,10-8mol/L우미탁미정시Tc축단(P＜0.05),불동농도우미탁미정시Am화To 차이무통계학의의(P＞0.05).결론 10-7、10-6、10-5 mol/L우미탁미정가정농도의뢰성지격활대서장계막동맥평활기세포BKCa통도,시기강압작용적궤제지일.
Objective To evaluate the effects of different concentrations of dexmedetomidine on large-con-ductance Ca2+-activated K+ (BKca) channels in the rat mesenteric arterial smooth muscle (MASM) cells.Methods Sprague-Dawley rats of both sexes,weighing 180-220 g,were used in this study.Single MASM cell was freshly isolated from mesenteric arteries in two steps.Ten cells were chosen and studied.When holding potential was 40 mV and the concentration of free calcium ions was 10-7 mol/L,inside-out patch-clamp technique was used to record the single BKCa channel current before and after application of different concentrations of dexmedetomidine (0,10-9,10-8,10-7,10-6,10-5 mol/L).Total open probability (NPo),amplitude (Am),mean open time (To) and mean close time (To) of single BKca channel were observed and recorded.Results Compared with the baseline value,dexmedetomidine 10-7,10-6 and 10-5 mol/L increased NPo in a concentration-dependent man-ner,and dexmedetomidine 10-9,10-8,10-7,10-6,10-5mol/L shortened Tc (P ＜0.05 or 0.01).Compared with the value obtained when the concentration of dexmedetomidine was 10-9 mol/L,Tc was significantly shortened when the concentration of dexmedetomidine was 10-8 mol/L (P ＜ 0.05),and no significant change was found in Am and To obtained when different concentrations of dexmedetomidine were applied (P ＞ 0.05).Conclusion Dexmedetomidine 10-7,10-6 and 10-5 mol/L activate BKca channels in rat MASM cells in a concentration-depen-dent manner,which is one of the mechanisms of decrease in blood pressure by dexmedetomidine.