[Atypical responses to dopamine of Helix pomatia neurons]

Atypical dopamine responses of Helix pomatia neurons accompanied by a fall in passive membrane permeability (an increase of the input resistance) were discovered. The reversal potential of the depolarizing atypical response amounted to -83 +/- 7 mV, and that of the hyperpolarizing response to -15 -20 mV. These values coincided with the reversal potentials for the hyperpolarizing and depolarizing responses to dopamine, that developed as membrane permeability increased. Biphasic dopamine responses are also described, in which the first phase is determined by an increase, while the second one with a decrease of membrane permeability. It is suggested that atypical dopamine responses are associated with specific types of ionic channels and are mediated via specific dopamine receptors.