In the mammalian CNS,
hypoxia causes a wide range of physiological effects, and these effects often depend on the stage of development. Among the effects are alterations in pH homeostasis. Na+-coupled HCO3(-) transporters can play critical roles in intracellular pH regulation and several, such as NCBE and NBCn1, are expressed abundantly in the central nervous system. In the present study, we examined the effect of chronic continuous
hypoxia on the expression of two electroneutral Na-coupled HCO3(-) transporters, SLC4a7 (NBCn1) and SLC4a10 (NCBE), in mouse brain, the first such study on any
acid-base transporter. We placed the mice in normobaric chambers and either maintained normoxia (21% inspired O2) or imposed continuous chronic
hypoxia (11% O2) for a duration of either 14 days or 28 days, starting from ages of either postnatal age 2 days (P2) or P90. We assessed
protein abundance by Western blot analysis, loading equal amounts of total
protein for each condition. In most cases,
hypoxia reduced NBCn1 levels by 20-50%, and NCBE levels by 15-40% in cerebral cortex, subcortex, cerebellum, and hippocampus, both after 14 and 28 days, and in both pups and adults. We hypothesize that these decreases, which are out of proportion to the expected overall decreases in brain
protein levels, may especially be important for reducing energy consumption.