MEMBRANE-POTENTIAL, RESTING CALCIUM AND CALCIUM TRANSIENTS IN ISOLATED MUSCLE-FIBERS FROM NORMAL AND DYSTROPHIC MICE
MEMBRANE-POTENTIAL, RESTING CALCIUM AND CALCIUM TRANSIENTS IN ISOLATED MUSCLE-FIBERS FROM NORMAL AND DYSTROPHIC MICE
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DOI：
10.1113/jphysiol.1993.sp019801
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发表时间：
1993-09-01
影响因子：
5.5
通讯作者：
HEAD, SI
中科院分区：
文献类型：
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作者：
HEAD, SI
1.从3-9周龄的营养不良mdx和对照C57 BL/10小鼠的趾短屈肌（FDB）酶促分离单个骨骼肌纤维。在这个年龄范围内，大多数（> 95%）mdx纤维形态正常。mdx和对照小鼠的静息膜电位（RMP）之间无显著差异，分别为-71.2+/-1.21（n = 26）和-70.6+/-1.15 mV（n = 42）.在负性大于-60 mV的RMP下，营养不良mdx细胞中的静息钙（用fura-2记录，游离酸离子转运到细胞中）与正常动物无显著差异，分别为45.7+/-4.1（n = 10）和46.2+/-3.9 nM（n = 9）。静息细胞溶质钙浓度与RMP同时测定。在-60至-17 mV之间的RMP下，mdx和对照组的静息钙浓度均增加，范围为79.3至252 nM。这种增加很可能是由于慢钙电流的激活。5. Fura-2钙瞬变是通过使用细胞内微电极刺激细胞和记录电位变化的单一动作电位刺激产生的。与正常动物相比，mdx中响应于单个动作电位的钙瞬变在22 ℃时的上升时间（T（p））或半衰减时间（T1/2）之间没有显著差异，分别为5.9+/-0.34（n = 8）和5.4+/-0.36 ms（n = 7）; 39.5+/-2.9（n = 8）和40.75+/-3.7 ms（n = 7）。总之，在3-9周龄范围内，肌养蛋白的缺乏似乎不影响形态正常的FDB mdx纤维的RMP、静息钙或钙瞬时参数。
1. Single skeletal muscle fibres were enzymatically isolated from the flexor digitorum brevis muscles (FDB) of dystrophic mdx and control C57BL/10 mice aged 3-9 weeks. In this age range the majority (> 95%) of the mdx fibres were morphologically normal.2. There was no significant difference between the resting membrane potential (RMP) of mdx and control mice, -71.2+/-1.21 (n = 26) and -70.6+/-1.15 mV (n = 42), respectively.3. At RMP more negative than -60 mV the resting calcium (recorded with fura-2, free acid ionophoresed into cell) in the dystrophic mdx cells was not significantly different from the normal animals, 45.7+/-4.1 (n = 10) and 46.2+/-3.9 nM (n = 9), respectively.4. The resting cytosolic calcium concentration was measured simultaneously with the RMP. At RMP between -60 to -17 mV there was an increase in the resting calcium concentration in both mdx and control ranging from 79.3 to 252 nM. This increase was most probably due to the activation of the slow calcium current.5. Fura-2 calcium transients were produced via single action potential stimulation using an intracellular microelectrode both to stimulate the cell and record potential changes. There was no significant difference between the rise time (T(p)) or half-decay time (T1/2) at 22-degrees-C of the calcium transient in response to a single action potential in mdx compared to normal animals, 5.9+/-0.34 (n = 8) and 5.4+/-0.36 ms (n = 7); 39.5+/-2.9 (n = 8) and 40.75+/-3.7 ms (n = 7), respectively.6. In conclusion it appears that over the age range 3-9 weeks the absence of dystrophin does not affect the RMP, resting calcium or calcium transient parameters of morphologically normal FDB mdx fibres.