[Thyroliberin blocks potassium A-current in neurons of the respiratory center of adult rats in vitro].

TRH is a well-known respiratory active neuropeptide. To study neuronal mechanisms of its activity, we have tested the effects of TRH on the potassium A-current in neurons of the ventrolateral solitary tract nucleus and pre-Botzinger complex in voltage-clamp experiments on adult rat brain slices. A-current was present in the neurons and it was partially and reversibly blocked by administration of THR (10(-8) M) to the bath solution. The significant decrease in amplitude of A-current was accompanied by the increase in inactivation constant (t). The effect of TRH on A-current amplitude was simulated by 5 mM 4-aminopyridine. The results presented here indicate that the stimulatory effects of TRH on neurons of the respiratory centre can be at least partially explained by its ability to block the potassium A-current.