Adams B A, Beam K G
Department of Physiology, Colorado State University, Fort Collins 80523.
FASEB J. 1990 Jul;4(10):2809-16. doi: 10.1096/fasebj.4.10.2165014.
Muscular dysgenesis (mdg) is a lethal autosomal, recessive mutation of mice. Skeletal muscle from dysgenic mice is paralyzed due to the failure of excitation-contraction (E-C) coupling. Considerable evidence indicates that this failure results from the absence of a specific gene product, the alpha 1 subunit of the skeletal muscle receptor for dihydropyridine calcium channel modifiers. This dihydropyridine receptor is hypothesized to function in E-C coupling of normal skeletal muscle as the voltage sensor that triggers calcium release from the sarcoplasmic reticulum and thereby causes contraction. The skeletal muscle dihydropyridine receptor is also postulated to function as the ion channel responsible for a slowly activating, dihydropyridine-sensitive calcium current (Islow). Dysgenic skeletal muscle lacks Islow but expresses, at low levels, a distinctly different dihydropyridine-sensitive calcium current (Idys). The channel protein underlying Idys is incapable of serving as a voltage sensor for E-C coupling. Studies using dysgenic skeletal muscle have provided significant insight into the role of dihydropyridine receptors in E-C coupling.
肌肉发育不全（mdg）是小鼠的一种致死性常染色体隐性突变。发育不全小鼠的骨骼肌因兴奋 - 收缩（E - C）偶联失败而麻痹。大量证据表明，这种失败是由于缺乏一种特定的基因产物，即二氢吡啶钙通道调节剂骨骼肌受体的α1亚基。据推测，这种二氢吡啶受体在正常骨骼肌的E - C偶联中作为电压传感器发挥作用，触发肌浆网释放钙从而引起收缩。骨骼肌二氢吡啶受体还被假定作为负责缓慢激活的、对二氢吡啶敏感的钙电流（Islow）的离子通道发挥作用。发育不全的骨骼肌缺乏Islow，但低水平表达一种明显不同的对二氢吡啶敏感的钙电流（Idys）。Idys的通道蛋白不能作为E - C偶联的电压传感器。使用发育不全骨骼肌进行的研究为二氢吡啶受体在E - C偶联中的作用提供了重要见解。
