Intracellular potentials during protracted recording from the neurones of Hirudo medicinalis

Sologub, M. I. and Kiss, Tibor (1971) Intracellular potentials during protracted recording from the neurones of Hirudo medicinalis. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 38. pp. 97-105. ISSN 0365-3005

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Abstract

1. During protracted leading the resting and action potential of the giant neurones of Hirudo medicinalis were studied in normal physiological solution, in solution containing 50% of initial concentration of Na⁺ ions and in Na⁺-free solution. 2. The amplitude of the action potentials was lower than that of the resting potentials and proved to be in direct ratio to the extracellular Na concentration. In Na-free solution the generation of the action potentials ceased. The action potentials of Hirudo neurones proved to be Na⁺-dependent. Na ions play an active role also in setting the level of the resting potential. 3. Depending on the resistance of the microelectrodes three variants were established in the intial alteration of the resting potentials: initial increase, stable level and initial decrease. The initial hyperpolarization observed after penetrating the microelectrodes with high resistance into the cell was connected with the increases of the activity of Na/К pump and the intracellular metabbolism. 4. Fast depolarization of the resting potential and the reversal were observed only in the presence of Na ions. Thus the depolarization and the reversal are caused by the influx of Na ions at the end of the protracted leading. 5. It is suggested that the slow alterations of the resting potential and the fast changes leading to the generation of action potential are based on same ion mechanisms.

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