Analysis of two types of dopaminergic responses of neurons of the spinal ganglia of rats.

It was established, in experiments on isolated spinal ganglia of adult rats in conditions of intracellular recording, that dopamine (1 microM/liter) elicits depolarized responses in 61% of neurons, hyperpolarized in 20% of neurons, and depolarized-hyperpolarized in 19% of neurons. The depolarized responses are associated with the activation of D1 dopamine receptors, and are governed by the shift of cAMP-dependent cation (sodium) channels to the conducting state. The hyperpolarized responses are triggered by the activation of D2 dopamine receptors, which by means of HTP-binding protein convert the potassium channels to the conducting state. The change in the polarization of neurons with the action of dopamine influences their electrical excitability variously.