Voltage-dependent current evoked by dopamine and octopamine in Aplysia.

Octopamine and dopamine evoke a slow voltage-dependent inward current in neurons of Aplysia. The responses are present only at depolarized potentials (greater than -40 mV). They are insensitive to changes in potassium, persist after removal of sodium, are not reduced by low chloride solution, and are blocked by cadmium. Because of the similarities in voltage-dependence, time course and ionic sensitivities, the ionic mechanism of the voltage-dependent responses to octopamine and dopamine are concluded to be the same as that of the voltage-dependent response to serotonin reported previously.