Grossie J
Am J Physiol. 1978 Mar;234(3):C90-5. doi: 10.1152/ajpcell.1978.234.3.C90.
Basic mechanical and electrical properties of rat extensor muscle were analyzed 4--6 wk after thyroid removal. Isometric twitch tensions in thyroidectomized (Tx) rat muscle varied considerably, with over 60% of the muscles showing abnormally low values and the remainder showing a high twitch force. The duration of the twitch was significantly increased from 137 to 245 ms but contraction and half-relaxation times were not significantly changed. Tetanic force was not effected by thyroidectomy. Electrical properties of the muscle fiber membranes were made exclusively via intracellular techniques. The resting membrane potential was slightly higher in thyroidectomized rats (-79 mV) as compared to sham controls (-78 mV). Both direct and indirect action potentials showed higher overshoots, amplitudes, and rates of depolarization in thyroidectomized rats. The threshold of the indirect action potential appeared at a higher transmembrane potential as compared to sham-operated controls. The input resistance, space constant, time constant, and specific membrane resistance were all significantly increased in thyroidectomized rat extensor muscle, whereas fiber diameter and capacitance were significantly decreased. Estimates of specific ionic conductance show that both potassium and chloride conductance are decreased in thyroidectomized rat muscle.
在甲状腺切除术后4 - 6周，对大鼠伸肌的基本力学和电学特性进行了分析。甲状腺切除（Tx）大鼠肌肉的等长收缩张力差异很大，超过60%的肌肉表现出异常低的值，其余的则表现出高收缩力。收缩的持续时间从137毫秒显著增加到245毫秒，但收缩时间和半松弛时间没有显著变化。强直收缩力不受甲状腺切除术的影响。肌肉纤维膜的电学特性完全通过细胞内技术进行测定。与假手术对照组（-78 mV）相比，甲状腺切除大鼠的静息膜电位略高（-79 mV）。在甲状腺切除大鼠中，直接和间接动作电位均表现出更高的超射、幅度和去极化速率。与假手术对照组相比，间接动作电位的阈值出现在更高的跨膜电位。甲状腺切除大鼠伸肌的输入电阻、空间常数、时间常数和比膜电阻均显著增加，而纤维直径和电容则显著降低。比离子电导率的估计表明，甲状腺切除大鼠肌肉中的钾离子和氯离子电导率均降低。
