Myosin heavy chain isoform composition and Ca2+transients in fibres from enzymatically dissociated murine soleus and extensor digitorum longus muscles
Myosin heavy chain isoform composition and Ca2+transients in fibres from enzymatically dissociated murine soleus and extensor digitorum longus muscles
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DOI：
10.1113/jphysiol.2009.180893
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发表时间：
2010-01-01
影响因子：
5.5
通讯作者：
Caputo, Carlo
中科院分区：
文献类型：
--
作者：
Calderon, Juan C.;Bolanos, Pura;Caputo, Carlo
在成年小鼠趾长伸肌 (EDL) 和比目鱼肌的完整酶解纤维中获得了用快速 Ca2+ 染料 MagFluo-4 AM 和肌球蛋白重链 (MHC) 电泳图谱报告的电激发 Ca2+ 瞬变。通过荧光显微镜和电泳分析了 39 根纤维（23 根来自比目鱼肌，16 根来自 EDL）。这些光纤分组如下：第 1 组包括 13 根 I 型光纤和 4 根 IC 型光纤；第 2 组包括 2 根 IIC 型纤维、3 根 IIA 纤维和 1 根 I/IIA/IIX 纤维；第 3 组包括 4 根 IIX 型纤维和 1 根 IIX/IIB 型纤维；第 4 组包括 2 根 IIB/IIX 型光纤和 9 根 IIB 型光纤。第 1、2、3 和 4 组中获得的 Ca2+ 瞬变具有以下动力学参数（平均值 +/- s.e.m.）： 振幅（δ F/F）：0.61 +/- 0.05、0.53 +/- 0.08、0.61 +/- 0.06 和 0.61 +/- 0.03；上升时间（毫秒）：1.64 +/- 0.05、1.35 +/- 0.05、1.18 +/- 0.06 和 1.14 +/- 0.04；半幅宽度（ms）：19.12 +/- 1.85、11.86 +/- 3.03、4.62 +/- 0.31 和 4.23 +/- 0.37；和衰减时间常数（tau(1) 和 tau(2)，ms）：3.33 +/- 0.13 和 52.48 +/- 3.93、2.69 +/- 0.22 和 41.06 +/- 9.13、1.74 +/- 0.06 和 12.88 +/- 1.93 和 1.56 +/- 0.11分别为 9.45 +/- 1.03。四组之间的统计差异以及Ca2+释放和清除参数分布的分析表明，存在从慢到快的连续体，这与从纯I型到纯IIB型的MHC连续体平行。然而，IIA 型纤维在 Ca2+ 释放方面更像 IIX 和 IIB 纤维，但在 Ca2+ 清除方面更接近 I 型纤维。总之，我们首次展示了整个纤维类型连续体的 Ca2+ 瞬变多样性，并将这种功能多样性与骨骼肌纤维的结构和生化多样性相关联。
Electrically elicited Ca2+ transients reported with the fast Ca2+ dye MagFluo-4 AM and myosin heavy chain (MHC) electrophoretic patterns were obtained in intact, enzymatically dissociated fibres from adult mice extensor digitorum longus (EDL) and soleus muscles. Thirty nine fibres (23 from soleus and 16 from EDL) were analysed by both fluorescence microscopy and electrophoresis. These fibres were grouped as follows: group 1 included 13 type I and 4 type IC fibres; group 2 included 2 type IIC, 3 IIA and 1 I/IIA/IIX fibres; group 3 included 4 type IIX and 1 type IIX/IIB fibres; group 4 included 2 type IIB/IIX and 9 type IIB fibres. Ca2+ transients obtained in groups 1, 2, 3 and 4 had the following kinetic parameters (mean +/- s.e.m.): amplitude (delta F/F): 0.61 +/- 0.05, 0.53 +/- 0.08, 0.61 +/- 0.06 and 0.61 +/- 0.03; rise time (ms): 1.64 +/- 0.05, 1.35 +/- 0.05, 1.18 +/- 0.06 and 1.14 +/- 0.04; half-amplitude width (ms): 19.12 +/- 1.85, 11.86 +/- 3.03, 4.62 +/- 0.31 and 4.23 +/- 0.37; and time constants of decay (tau(1) and tau(2), ms): 3.33 +/- 0.13 and 52.48 +/- 3.93, 2.69 +/- 0.22 and 41.06 +/- 9.13, 1.74 +/- 0.06 and 12.88 +/- 1.93, and 1.56 +/- 0.11 and 9.45 +/- 1.03, respectively. The statistical differences between the four groups and the analysis of the distribution of the parameters of Ca2+ release and clearance show that there is a continuum from slow to fast, that parallels the MHC continuum from pure type I to pure IIB. However, type IIA fibres behave more like IIX and IIB fibres regarding Ca2+ release but closer to type I fibres regarding Ca2+ clearance. In conclusion, we show for the first time the diversity of Ca2+ transients for the whole continuum of fibre types and correlate this functional diversity with the structural and biochemical diversity of the skeletal muscle fibres.