Contribution of BK(Ca) channels of neurons in rostral ventrolateral medulla to CO-mediated central regulation of respiratory rhythm in medullary slices of neonatal rats

Abstract

We recently described that carbon monoxide (CO) participated in the regulation of rhythmic respiration in medullary slices. The present study was undertaken to further assess whether the large-conductance calcium-activated potassium channels (BK(Ca) channels) are involved in the CO-mediated central regulation of respiratory rhythm in medullary slices. The rhythmic discharge of hypoglossal rootlets of medullary slices of neonatal rats was recorded. We observed that blocking BK(Ca) channels could partially abolish the effects of CO on the rhythmic bursts of hypoglossal rootlets. With whole-cell patch-clamp recording technique, we further observed that CO could reversibly augment potassium current density of the neurons in the rostral ventrolateral medulla. The CO-induced increase in potassium current was entirely blocked by the pretreatment of slices with BK(Ca) channels blocker; whereas blockade of CO generation with zinc protoporphyrin-IX produced an opposite response. Altogether, these data indicate that BK(Ca) channels of the neurons in neonatal rostral ventrolateral medulla could be activated by CO and involved in CO-mediated central regulation of respiratory rhythm in medullary slices.