Frequency-dependence of action potential on non myelinated nerve of Anodonta cygnea L. (Pelecypoda)

Lábos, Elemér and Salánki, János and Varanka, István (1969) Frequency-dependence of action potential on non myelinated nerve of Anodonta cygnea L. (Pelecypoda). A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 36. pp. 41-56. ISSN 0365-3005

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Abstract

Isolated cerebro-visceral connective of Anodonta cygnea L. was examined. Its response to a square-pulse train showed the following features 1. At low frequencies (ω = 1-3 cps) it shows transient amplitude-increase, while in the higher range the amplitudes of consecutive potentials decrease. Very often a stable oscillation of amplitude has been observed. 2. Let the nerve he stimulated several times, the amplitude decreases to a relatively steady value without any initial increase. The steady-state value is about 50 per cent of the original when the frequency is 3 cps; at 8-10 cps its value is less than 10 per cent. The frequency response follows the formula of аω ~ a₀/(l + T₀² ω²). It is furthermore pulse-duration and strength dependent. 3. The suprathreshold high-frequency stimulation (20-150 cps) elicits only on- and off- responses. On-response is evoked also by subthreshold highfrequency stimulation. Its frequency-dependence is: Aon ~ Amax/(1 + ω₀⁴ω⁻⁴). The number of pulses required to induce a maximal response decreases with an increase of frequency. 4. A fatigued nerve (after about 2 hours of continous stimulaton responds firstly by a random distribution of amplitudes later extra-responses appear recurring very precisely. The time lapse between two extra-responses is τ ~ ω⁻¹ exp (1,71 ω⁰’⁷⁶); ω in cps. Because of the above enumarated properties of CVc, the frequency-dependence of the effector (adductor)-tonus can be interpreted only by taking into account the role of the intermediated ganglia. At high frequency stimulation only the on-response represents an excitation. CVc is equivalent with a low frequency, nonlinear cable having active and inductive elements, and being highly damped.

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