Intracellular acidosis and pH regulation in central respiratory chemoreceptors.

Dysfunctions of brainstem regions responsible for central CO2 chemoreception have been proposed as an underlying pathophysiology of Sudden Infant Death Syndrome (SIDS). We recorded respiratory motor output and intracellular pH (pHi) from chemosensitive neurons in an in vitro tadpole brainstem during normocapnia and hypercapnia. Flash photolysis of the H+ donor nitrobenzaldehyde was used to induce focal decreases in pHi alone. Hypercapnia and flash photolysis significantly decreased pHi from normocapnia. In addition, chemoreceptors did not regulate pHi during hypercapnia, but demonstrated significant pHi recovery when only pHi was reduced by flash photolysis. Respiration was stimulated by decreases in pHi (hypercapnia and flash photolysis) by decreases in burst cycle. These data represent our ability to load the brainstem with nitrobenzaldehyde without disrupting the respiration, to quantify changes in chemoreceptor pHi recovery, and to provide insights regarding mechanisms of human health conditions with racial/ethnic health disparities such as SIDS and Apnea of Prematurity (AOP).