Abstract
A simple model for the extracellular action potential of a single muscle fibrein situ is proposed. This model is a dipole moving at a uniform speed in an axial direction, immersed in a volume conductor of extent large compared with the dipole length. The peak to peak duration of the potential recorded by a small electrode increases with distance of the electrode from the site of maximum amplitude. The model can be applied to show why the measured duration of the action potential of a motor unit is necessarily longer than that of the constituent single fibre.
Sommaire
On propose un modèle simple pour le potentiel de l'action extracellulaire d'une seule fibre musculaire sur place. Ce modèle est un dipôle se déplaçant à vitesse uniforme dans une direction axiale, et submergé dans un conducteur de volume d'étendue large en comparaison avec la longueur du dipôle. La durée crête à crête du potentiel enregistré par une petite électrode augmente avec la distance de l'électrode au lieu d'amplitude maximale. Le modèle peut être appliqué pour montrer pourquoi la durée mesurée du potentiel d'action d'un élément moteur est nécessairement plus longue que celle de la fibre simple constituante.
Zusammenfassung
Ein einfaches Modell für das extrazellulare Funktionspotential einer einzigen in situ Muskelfaser wird unterbreitet. Dieses Modell ist ein Dipol, der sich mit einer gleichförmigen Geschwindigkeit in axialer Richtung bewegt und der in einem Rauminhaltleiter eingetaucht ist, welcher, verglichen mit der Dipollänge, gross ist. Die Dauer des Potentials von Spitze zu Spitze, wie es von einer kleinen Elektrode registriert wird, verlängert sich mit-Entfernung der Elektrode von der Stelle maximalen Ausschlags. Das Modell kann verwandt werden zu zeigen, warum die gemessene Dauer des Aktionspotentials einer Motoreinheit notwendigerweise länger ist, als die des Einzelfaserbestandteils.
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George, R.E. The summation of muscle fibre action potentials. Med. & biol. Engng. 8, 357–365 (1970). https://doi.org/10.1007/BF02477663
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DOI: https://doi.org/10.1007/BF02477663