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低氧夏氧对豚鼠心肌细胞钾通道电流及钙通道电流的影响 总被引:9,自引:1,他引:8
目的:建立豚鼠心肌细胞低氧复氧模型,研究低氧复氧对心肌细胞ATP敏感性钾通道及L型钙通道电流(Lca-i.)的影响,以探讨心肌低氧时动作电位时程(APD)缩短的机制,方法,采用膜片钳技术记录豚鼠心肌细胞动作电位,钾通道电流及钙通道电流,结果,发现低氧5~20分钟后豚鼠心肌细胞APD明显缩短(由384±65ms降至188±46ms,P〈0.05),外向性钾电流明显增加,电流-电压曲线随去极化增加呈线 相似文献
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本文对20例男性心肌梗塞患者及与之配对的20例正常人红细胞胰岛素受体进行检测,并根据Scatchard曲线计算受体的高、低亲和力位点数(Q1、Q2)及亲和力常数(K1、K2),同时测定了血浆性激素及胰岛素水平;并采用离体竞争结合的方法,研究性激素对胰岛素结合离体红细胞的影响。结果显示,心肌梗塞组K1、Q2、K2低于正常对照组;直线相关分析发现,血浆睾酮与K1呈负相关,与Q2呈正相关,胰岛素与Q2呈负相关;竞争结合实验发现睾酮能减低胰岛素与受体的结合,而雌二醇未见影响。这提示,心肌梗塞患者的胰岛素抵抗可能与胰岛素受体数目减低及亲和力改变有关,睾酮可降低红细胞胰岛素受体的结合。 相似文献
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低氧复氧对豚鼠心肌细胞钾通道电流及钙通道电流的影响 总被引:7,自引:0,他引:7
目的:建立豚鼠心肌细胞低氧复氧模型,研究低氧复氧对心肌细胞ATP敏感性钾通道及L型钙通道电流(ICa-L)的影响,以探讨心肌低氧时动作电位时程(APD)缩短的机制。方法:采用膜片钳技术记录豚鼠心肌细胞动作电位、钾通道电流及钙通道电流。结果:发现低氧5~20分钟后豚鼠心肌细胞APD明显缩短(由384±65ms降至188±46ms,P<0.05),外向性钾电流明显增加,电流-电压曲线随去极化增加呈线性变化,且能被优降糖所抑制,显示ATP敏感性钾通道开放。低氧可抑制ICa-L,ICa-L峰值降低(由1.35±0.18nA降至0.76±0.21nA,P<0.05),电流-电压曲线上移,复氧后APD可很快恢复,ICa-L则不能恢复。结论:本研究提示低氧时豚鼠心肌细胞APD缩短不仅为ATP敏感性钾通道开放所致,而且尚有内向性钙电流抑制过程参与。 相似文献
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镁离子对低氧心肌保护作用的离子通道机制探讨 总被引:8,自引:0,他引:8
探讨Mg2+对低氧心肌细胞保护作用的离子通道机制。方法采用膜片钳全细胞记录技术及细胞内透析的方法观察低氧时Mg2+对心肌细胞钾电流、钙电流、Na+-Ca2+交换电流及短暂性内向电流的调节作用。结果对10个细胞观察显示常氧时细胞内10mmol/LMg2+对动作电位无明显影响,但可显著抑制低氧时动作电位时程的缩短(P<0.05),同时细胞内Mg2+对10分钟低氧引起的外向性钾电流有明显的抑制作用,对10个细胞观察显示除极至0mV时其电流值从对照的2130±243pA降至1189±211pA,P<0.01;在常氧时细胞外10mmol/LMg2+对Na+、Ca2+交换电流有部分抑制作用,细胞外Mg2+可显著降低复氧早期短暂性内向电流的诱发率。结论细胞内Mg2+可抑制低氧心肌细胞K+外流,并对维持细胞内高钾及心肌细胞膜的正常兴奋性有重要意义。而细胞外Mg2+对防止心肌缺血再灌流引起的钙超载有一定的作用。 相似文献
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Objective To develop a cellular model of preconditioning by a brief period of hypoxia in isolated guinea pig cardiomyocytes and to determine whether or not an ATP sensiti ve K(+) (K(ATP)) channel is involved in ischemic precond itioning. Methods Single myocytes were isolated from the ventricle of adult guinea pigs.The expe rimental chamber allowed the cells to be exposed to low O(2)pressure.During h ypoxic preconditioning, the cells were equilibrated with normaxic solution for 1 0 minutes and then exposed to hypoxia for 5 minutes, followed by 10 minutes of re oxygenation.The cells were then subjected to 20-180 minutes of hypoxia and reoxygenation.Ionic currents were studied with the patch clamp technique in w hole-cell and cell-attached configurations. Results A 5-minute hypoxic preconditioning offered a significant protection from cell i n jury in subsequent hypoxia-reoxygenation.After a latency of more than 15 minu tes, hypoxia induced a time-independent outward K(+) current which could be blo cked by 5 μmol/L glibenclamide.At 10 mV, the current increased from 78 ±1 5 pA to 1581±153 pA (P<0.01, n=18).However, the latency to develop K(ATP) channel currents (I(KATP)) was greatly shortened in preconditioned c ells, and the current was increased acceleratively.At 10 mV, the current more than 4 nA was recorded in preconditioning cells.In the single channel record ings, the time interval from the first channel opening to maximum opening was also markedly abbreviated in preconditioned cells.Conclusion Isolated guinea pig cardiomyocytes can be preconditioned with a brief period of hypoxia.This hypoxic preconditioning may modify the K(ATP) channel, and make the channel open more readily during the second hypoxia. 相似文献
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对40例冠心病患者及30例正常人进行糖耐量、胰岛素及C肽释放试验,并计算胰岛素敏感指数。发现冠心病患者血糖面积、空腹胰岛素水平及胰岛素面积、空腹C肽水平及C肽面积均高于正常人,而胰岛素敏感指数低于正常。提示冠心病患者存在高胰岛素血症及胰岛素抵抗。 相似文献
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患者男,66岁。因反复腹痛伴腹胀、呕吐3年曾先后3次在本院住院治疗。第1次为2006年7月29日至8月3日,入院时腹部X线透视(腹透)检查示左侧上、中腹部多个气液平面,肠管充气、扩张,右侧上中腹部一气液平面,长约8cm。 相似文献