The effect of ACh: acetylcholine; 5HT: serotonin; NA: noradrenaline; and DA: dopamine, added into the bathing fluid was investigated on the Br type neurone (RPal cell) of the snail, Helix pomatia at 22°C, 7°C and above 30°C. Acetylcholine caused an increase of activity at all the temperatures. The effect appeared instantaneously but lasted for a short time. After serotonin application, synaptic potentials (EPSP's) appeared at each temperature, evoking extra spikes. The characteristic bimodal activity pattern of the cell remained practically intact. Noradrenaline blocked potential generation at each temperature. Dopamine had a biphasic effect: it inhibited spike activity for 2 - 2.5 min, then action potential generation reappeared. In the later phase, depolarization and the presence of EPSP's were characteristic. It is supposed that Ach, NA and DA are directly influencing the permeability of the soma membrane, while the effect of 5HT and the late effect of DA is the result of synaptic activation caused either by stimulation of the neurones connected synaptically to the Br type cell, or by a direct effect on the synaptic region of the investigated cell.
|Number of pages||9|
|Journal||Acta physiologica Academiae Scientiarum Hungaricae|
|Publication status||Published - Dec 1 1973|
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