Calcium currents and transients in co-cultured contracting normal and Duchenne muscular dystrophy human myotubes
Calcium currents and transients in co-cultured contracting normal and Duchenne muscular dystrophy human myotubes
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DOI：
10.1111/j.1469-7793.2001.00343.x
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发表时间：
2001-07-15
影响因子：
5.5
通讯作者：
Cognard, C
中科院分区：
文献类型：
--
作者：
Imbert, N;Vandebrouck, C;Cognard, C
1. 本研究的目的是探讨正常和杜氏肌营养不良（DMD）人收缩肌管与附着背根神经节的大鼠脊髓外植体共培养在钙运动方面的差异。记录膜电位、细胞内钙浓度变化及T型和l型钙电流。此外，利用电子显微镜对共培养物的超微结构进行了描述性和定量研究。静息膜电位在DMD组（-61.4 +/- 1.1 mV）略低于正常肌管组（-65.5 +/- 0.9 mV）。两种类型的肌管均显示自发动作电位（平均放电频率分别为0.42和0.16 Hz），触发了Indo-1.3测量的自发钙瞬态。在自发性Ca（2+）瞬态下，DUD肌管的时间积分（97 +/- 8 nM s）明显大于正常肌管（67 +/- 13 nM s）。膜片钳记录的L型和t型电流密度在DMD细胞中（分别为2.0 +/- 0.5和0.90 +/- 0.19 pA pF(-1)）小于正常细胞（分别为3.9 +/- 0.7和1.39 +/- 0.30 pA pF(-1)）。电压依赖性失活关系揭示了T型和l型电流失活半峰时（V-h,V-0.5）的调节电位向负电位较低的方向转移，从正常细胞的-72.1 +/- 0.7和-53.7 +/- 1.5 mV分别到DMD细胞的-61.9 +/- 1.4和-29.2 +/- 1.4 mV。电镜下的描述和定量研究表明，与正常肌管相比，DMD肌管发育更早。在相同表观尺寸下，DMD肌管的电容（408 +/- 45pf）明显大于正常肌管（299 +/- 34pf）。综上所述，这些结果表明，正常肌管和DMD肌管之间T型和l型钙电流的差异不能简单地解释DMD肌管中钙稳态的所有变化，因此表明与正常肌管相比，DMD肌管中其他跨膜钙运输机制也必须改变。
1. The goal of the present study was to investigate differences in calcium movements between normal and Duchenne muscular dystrophy (DMD) human contracting myotubes co-cultured with explants of rat spinal cord with attached dorsal root ganglia. Membrane potential, variations of intracellular calcium concentration and T- and L-type calcium currents were recorded. Further, a descriptive and quantitative study by electron microscopy of the ultrastructure of the co-cultures was carried out.2. The resting membrane potential was slightly less negative in DMD (-61.4 +/- 1.1 mV) than in normal myotubes (-65.5 +/- 0.9 mV). Both types of myotube displayed spontaneous action potentials (mean firing frequency, 0.42 and 0.16 Hz, respectively), which triggered spontaneous calcium transients measured with Indo-1.3. The time integral under the spontaneous Ca (2+) transients was significantly greater in DUD myotubes (97 +/- 8 nM s) than in normal myotubes (67 +/- 13 nM s).4. The L- and T-type current densities estimated from patch-clamp recordings were smaller in DMD cells (2.0 +/- 0.5 and 0.90 +/- 0.19 pA pF(-1), respectively) than in normal cells (3.9 +/- 0.7 and 1.39 +/- 0.30 pA pF(-1), respectively).5. The voltage-dependent inactivation relationships revealed a shift in the conditioning potential at which inactivation is half-maximal (V-h,V-0.5) of the T- and L-type currents towards less negative potentials, from -72.1 +/- 0.7 and -53.7 +/- 1.5 mV in normal cells to -61.9 +/- 1.4 and -29.2 +/- 1.4 mV in DMD cells, respectively,6. Both descriptive and quantitative studies by electron microscopy suggested a more advanced development of DMD myotubes as compared to normal ones. This conclusion was supported by the significantly larger capacitance of the DMD myotubes (408 +/- 45 pF) than of the normal myotubes (299 +/- 34 pF) of the same apparent size.7. Taken together, these results show that differences in T- and L-type calcium currents between normal and DMD myotubes cannot simply explain all observed alterations in calcium homeostasis in DMD myotubes, thus suggesting that other transmembrane calcium transport mechanisms must also be altered in DMD myotubes compared vith normal myotubes.