KCC and NKCC activity affect spike frequency adaptation in CO2‐sensitive avian intrapulmonary chemoreceptors (1092.3)

Abstract

IPC are respiratory chemoreceptors that exhibit SFA, have phasic and tonic CO2 sensitivity, and help control breathing in birds. In IPC, large changes in PCO2, pHi, and [HCO3]i occur with each breath. Here we test the hypothesis that Cl‐ transmembrane flux may be involved in IPC CO2 transduction to balance intracellular [HCO3‐] changes. Furosemide (FU), an equipotent inhibitor of both K+ ‐Cl‐ cotransport (KCC), which allows for Cl‐ efflux driven by the K+ gradient, and Na+ ‐K+ ‐2Cl‐ cotransport (NKCC), which allows for Cl‐ influx driven by the Na+ gradient, was given to anesthetized Anas platyrhynchos (N=6) while recording single‐unit IPC. FU progressively reduced SFA at 10‐40 mg/kg (p蠄0.0001). In contrast, tonic IPC discharge was decreased at low FU doses (0.5‐5 mg/kg, p蠄0.0001) but increased at higher dosages (10‐40 mg/kg, p蠄0.0001). Results suggest that IPC SFA and tonic CO2 sensitivity are influenced by KCC and/or NKCC, presumably by reducing ability of the cell to produce Cl‐ counter movements required by phasic [HCO3‐] changes.Grant Funding Source: Supported by NIH R15 HL087269‐02