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实验观察了钠氢交换或钠钙交换抑制剂 5 (N ,N 二甲基 )氨氯吡咪 (DMA)对正常和心肌肥厚大鼠分离心室肌细胞钙瞬变和细胞收缩的影响。通过负载荧光染料Fura 2 /Am ,应用离子影像分析系统 (IonImagingSystem)同步测定离体大鼠心肌细胞钙瞬变和细胞长度。结果表明 :DMA 10 μmol/L分别使钙瞬变和细胞缩短从对照组的 2 0 9.6 0± 5 4.96和 3.0 7± 0 .97μm增加到 2 38.5 0± 80 .41和 4.0 7± 1.0 2 μm (P <0 .0 5 ,n =7)。应用特异性反向钠钙交换阻断剂KB R7943可完全阻断DMA的激动作用。DMA还可使尼卡地平抑制L 型钙通道后的钙瞬变和细胞收缩增加。在肥厚心肌细胞 ,DMA表现出相同的药理作用 ,但对钙瞬变和细胞缩短的刺激作用更强。结果表明 :DMA可通过反向钠钙交换途径增加正常和肥厚大鼠心肌细胞钙瞬变和细胞收缩 ,且对肥厚心肌细胞的影响比对正常心肌细胞大。
The effects of Na + exchange or sodium-calcium exchange inhibitor 5 (N, N-dimethyl) amiloride (DMA) on calcium transients and cell contraction in ventricular myocytes isolated from normal and hypertrophied rats were observed. Simultaneous determination of calcium transients and cell lengths in isolated rat cardiomyocytes was performed using a fluorescent dye, Fura 2 / Am, using the Ion Imaging System. The results showed that DMA 10 μmol / L increased calcium transients and cell shortening from 20 060 ± 5 4.96 and 3.0 7 ± 0.97 μm in the control group to 2 38.5 0 ± 80 .41 and 4.0 7 ± 1.0 2 μm, respectively (P <0. 05, n = 7). Application of specific reverse sodium-calcium exchange blocker KB R7943 completely blocked the excitement of DMA. DMA also enables nicardipine to inhibit calcium transients and cell contractions after L-type calcium channels. In hypertrophic cardiomyocytes, DMA shows the same pharmacological effect but is more stimulatory to calcium transients and cell shortening. The results showed that DMA could increase calcium transients and cell contraction in normal and hypertrophied rat myocytes by reversing Na + / Ca2 + exchange and had a greater effect on hypertrophic cardiomyocytes than normal cardiomyocytes.