Milton R L, Behforouz M A
Indiana University School of Medicine, Muncie Center for Medical Education, Ball State University, IN 47306, USA.
J Muscle Res Cell Motil. 1995 Aug;16(4):430-9. doi: 10.1007/BF00114508.
Na channel densities were measured in fast and slow twitch mouse skeletal muscle fibres using the loose patch voltage clamp technique. It was found that Na channel density was approximately four times greater in fast twitch fibres than in slow. Computer simulations of action potential propagation in these fibres strongly suggest that the higher channel densities in fast twitch fibres are necessary to maintain action potential amplitude and fidelity of transmission across the neuromuscular junction, especially during the periods of rapid stimulation that these fibres are subjected to by their motoneurons. Transplantation of a foreign nerve containing axons which had previously innervated fast twitch fibres on to a slow twitch muscle resulted in an approximate doubling of the Na channel density in fibres innervated by the foreign nerve. These results suggest that motoneurons may exert considerable control over Na channel density in the muscle fibres they innervate.
使用膜片钳技术测量了快速和慢速小鼠骨骼肌纤维中的钠通道密度。结果发现，快速收缩纤维中的钠通道密度大约是慢速收缩纤维中的四倍。对这些纤维中动作电位传播的计算机模拟强烈表明，快速收缩纤维中较高的通道密度对于维持动作电位幅度和跨神经肌肉接头的传递保真度是必要的，特别是在这些纤维受到其运动神经元快速刺激的时期。将先前支配快速收缩纤维的轴突的外来神经移植到慢速收缩肌肉上，导致外来神经支配的纤维中的钠通道密度大约增加了一倍。这些结果表明，运动神经元可能对其支配的肌肉纤维中的钠通道密度施加相当大的控制。
