Public University of Navarra, Department of Electrical and Electronic Engineering, 31006 Pamplona, Spain.
J Neurosci Methods. 2011 Apr 30;197(2):221-30. doi: 10.1016/j.jneumeth.2011.02.022. Epub 2011 Mar 29.
In situ recording of the intracellular action potential (IAP) of human muscle fibres is not yet possible, and consequently, knowledge concerning certain IAP characteristics is still limited. According to the core-conductor theory, close to a fibre, a single fibre action potential (SFAP) can be assumed to be proportional to the IAP second derivative. Thus, we might expect to be able to derive some characteristics of the IAP, such as the duration of its spike, from the SFAP waveform. However, SFAP properties not only depend on the IAP shape but also on the fibre-to-electrode (radial) distance and other physiological properties of the fibre. In this paper we, first, propose an SFAP parameter (the negative phase duration, NPD) appropriate for estimating the IAP spike duration and, second, show that this parameter is largely independent of changes in radial distance and muscle fibre propagation velocity. Estimation of the IAP spike duration from a direct measurement taken from the SFAP waveform provides a possible way to enhance the accuracy of SFAP models. Because IAP spike duration is known to be sensitive to the effects of fatigue and calcium accumulation, the proposed SFAP parameter, the NPD, has potential value in electrodiagnosis and as an indicator of IAP profile changes due to peripheral fatigue.
目前还无法对人体肌肉纤维的细胞内动作电位 (IAP) 进行实时记录，因此，有关某些 IAP 特征的知识仍然有限。根据核心导体理论，在纤维附近，可以假设单个纤维动作电位 (SFAP) 与 IAP 的二阶导数成正比。因此，我们可能期望能够从 SFAP 波形中得出 IAP 的某些特征，例如其尖峰的持续时间。然而，SFAP 的特性不仅取决于 IAP 的形状，还取决于纤维与电极（径向）的距离以及纤维的其他生理特性。在本文中，我们首先提出了一个适用于估计 IAP 尖峰持续时间的 SFAP 参数（负相持续时间，NPD），其次表明该参数在很大程度上不受径向距离和肌肉纤维传播速度变化的影响。从 SFAP 波形中直接测量得出 IAP 尖峰持续时间的估计值，可以提高 SFAP 模型的准确性。由于已知 IAP 尖峰持续时间对疲劳和钙积累的影响很敏感，因此所提出的 SFAP 参数 NPD 具有在电诊断中的潜在价值，并且可以作为由于外周疲劳导致 IAP 轮廓变化的指标。
