The effect of the change of electrode dimensions and distance on the action potential induced by electric excitation of the non-medullated nerve Anodonta cygnea L.

Lábos, Elemér (1965) The effect of the change of electrode dimensions and distance on the action potential induced by electric excitation of the non-medullated nerve Anodonta cygnea L. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 32. pp. 17-27. ISSN 0365-3005

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Abstract

1. From the cerebrovisceral connective (CVC) of Anodonta cygnea L. action potential was led off with RC amplifier (T=0.75 sec) excited by square impulse. 2. The amplifier used is of symmetric input (2x3.3 MΩ) the impulse of cathode output ( ~ 1000 Ω) the nerve of high resistance ( 1 MΩ per cm). 3. Excited with three electrodes the change of the electrode distances had the following effect on the action potential: a) Upon the increase of the distance of the stimulating pair of electrodes the action potential decreased very strongly and on a stretch linearly. The phenomenon is ascribed to the decrease of the stimulating current. b) Increase of the earth electrode (plate) length led to the decrease of the initially uniform artefact-action potential complex, to desynchronisation and separation of the artefact. Possible changes in the equivalent of the system were discussed. The phenomenon points to a connexion between the initial component and the stimulus irruption. Uncertainty of velocity measurement is due to the impulse of large extent. c) Increase of the distance between electrodes leading off points to the “lead separation effect” (Gasser). 4. Data obtained during the course of “symmetric” bipolar leading off seem to point out that symmetry can be hardly realized in the case of a nerve of high resistance. The reversal of the potential and the shifting of the proportions of components point to the complicated mechanism of wave spreading. 5. The factors examined point to some causes of the “variability” of the action potential which can not be left out of consideration when discussing the importance of the components.

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