A MTA Tihanyi Biológiai Kutatóintézetének Évkönyve 42. (1975)

1. ÁLLATTAN - Vadász István - Véró Mihály: Ion current temperature dependence of Br-type neuron of Helix pomatia L. = Helix pomatia L. Br-típusú sejtje ionáramainak hőmérsékletfüggése

ANNAL. BIOL. TIHANY 42 129-137 HUNGÁRIA 1975 ION CURRENT TEMPERATURE DEPENDENCE OF Br-TYPE NEURON OF HELIX POMATIA L. ISTVÁN VADÁSZ and MIHÁLY VÉRÓ Biological Research Institute of the Hungarian Academy of Sciences, Tihany, Hungary Received: 14th February, 1975 The temperature dependence of neuron activity patterns and of neuron activity parameters is known both for vertebrate animals ( Barker and Car­penter, 1970) and for invertebrate animals (Kerkut and Taylor, 1956). The change of ambient temperature will change the neuron resting potential (Hodgkin and Katz, 1949), and a similar significant change will also be intro­duced in the repetition frequency of the cells (Carpenter, 1967). Investigation of certain giant neurons showing burst activity proved the temperature de­pendence of the activity pattern: the characteristic activity pattern of the control disappears at low temperatures below 12°C and at high temperatures above 33°C (Wachtel and Wilson, 1973; Salánki et ab, 1973). Previous investigations carried out in our Institute (Salánki et ah, 1975) and also the work of other authors showed that probably several mecha­nisms were responsible for the slow periodical membrane potential change resulting in the burst activity pattern, and for the generation of the action potential. Investigations of different ion content solutions also showed that the generation of slow waves and action potentials is dependent on the ions involved (Junge and Stephens, 1973; Salánki et ah, 1975). It is known that the ion current during voltage clamp measurements has a marked temperature de­pendence (Hodgkin et al., 1952). Recognizing the decisive role of temperature in the activity pattern, the purpose of our present investigations has been the determination of the temperature dependence in the Br-type RPal cell of Helix pomatia L. Material and method The isolated ganglion of Helix pomatia L. has been placed in a perfusion chamber having a volume of 3 cm3. The temperature of the physiological solu­tion and the temperature of the ganglion have been adjusted to the values of 7, 22 and 33 degrees Centigrade, resp. The temperature adjustment has been performed by Peltier batteries driven by a special circuit (Véró, 1974a). Glass microelectrodes filled with 2.5 M KC1 having a resistance in the range of 4 to 7 Mohm have been used for recording the membrane and action potentials. Perfect compensation of the electrode potential was possible by the

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