Public University of Navarra, Department of Electrical and Electronic Engineering, 31006 Pamplona, Spain.
J Electromyogr Kinesiol. 2012 Feb;22(1):88-97. doi: 10.1016/j.jelekin.2011.06.005. Epub 2011 Sep 8.
In situ recording of the intracellular action potential (IAP) of human muscle fibres is not yet feasible, and consequently, knowledge about certain IAP characteristics of these IAPs is still limited. The ratio between the amplitudes of the second and first phases (the so-called peak-to-peak ratio, PPR) of a single fibre action potential (SFAP) is known to be closely related to the IAP profile. The PPR of experimentally recorded SFAPs has been found to be largely independent of changes in the fibre-to-electrode (radial) distance. The main goal of this paper is to analyze the effect of changes in different aspects of the IAP spike on the relationship between PPR and radial distance. Based on this analysis, we hypothesize about the characteristics of IAPs obtained experimentally. It was found that the sensitivity of the SFAP PPR to changes in radial distance is essentially governed by the duration of the IAP spike. Assuming that, for mammals, the duration of the IAP rising phase lies within the range 0.2-0.4ms, we tentatively suggest that the duration of the IAP spike should be over approximately 0.75ms, with the shape of the spike strongly asymmetric. These IAP characteristics broadly coincide with those observed in mammal IAPs.
目前尚无法对人体肌肉纤维的细胞内动作电位（IAP）进行现场记录，因此，关于这些 IAP 的某些 IAP 特征的知识仍然有限。单个纤维动作电位（SFAP）的第二相和第一相（所谓的峰峰比，PPR）之间的幅度比与 IAP 形态密切相关。实验记录的 SFAP 的 PPR 已被发现基本不受纤维与电极（径向）距离变化的影响。本文的主要目的是分析 IAP 尖峰的不同方面变化对 PPR 与径向距离之间关系的影响。基于此分析，我们对实验中获得的 IAP 特性进行了假设。结果发现，SFAP PPR 对径向距离变化的敏感性主要由 IAP 尖峰的持续时间决定。假设哺乳动物的 IAP 上升相持续时间在 0.2-0.4ms 范围内，我们推测 IAP 尖峰的持续时间应超过约 0.75ms，且尖峰形状强烈不对称。这些 IAP 特征与在哺乳动物 IAP 中观察到的特征大致吻合。
