Mehrke G, Brinkmeier H, Jockusch H
Developmental Biology Unit, University of Bielefeld, Federal Republic of Germany.
Muscle Nerve. 1988 May;11(5):440-6. doi: 10.1002/mus.880110505.
The hereditary neuromuscular syndrome of the mouse, "arrested development of righting response" (ADR), is characterized by after-contractions of skeletal muscle. In order to analyze the etiology of this hereditary defect, mutant and wildtype muscle fibers were studied by intracellular recording. Direct stimulation of ADR muscle fibers elicited runs of action potentials of 1-5 seconds duration, with declining amplitudes and varying frequencies. The electrical after-activity coincided with after-contractions of the fiber, and both phenomena could be suppressed by the membrane-stabilizing drug tocainide. Since similar runs of APs were observed with wildtype muscle in chloride-free medium, the possible involvement of chloride conductance in the ADR syndrome was studied. Although membrane time constants in wildtype muscle were 4 times prolonged in chloride-free medium, those of ADR muscle were only 1.4 times longer. This finding indicated a drastic reduction of chloride conductance of the ADR muscle membrane. We conclude that ADR is a myotonia, related in its etiology to hereditary myotonias of man.
小鼠的遗传性神经肌肉综合征“翻正反射发育停滞”（ADR）的特征是骨骼肌出现后收缩。为了分析这种遗传性缺陷的病因，通过细胞内记录对突变型和野生型肌纤维进行了研究。直接刺激ADR肌纤维会引发持续1 - 5秒的动作电位发放，其幅度逐渐减小且频率各异。电后活动与纤维的后收缩同时出现，并且这两种现象都可被膜稳定药物妥卡尼抑制。由于在无氯培养基中野生型肌肉也观察到了类似的动作电位发放，因此研究了氯电导在ADR综合征中可能的作用。尽管在无氯培养基中野生型肌肉的膜时间常数延长了4倍，但ADR肌肉的膜时间常数仅延长了1.4倍。这一发现表明ADR肌膜的氯电导大幅降低。我们得出结论，ADR是一种肌强直，其病因与人类遗传性肌强直有关。
