Sodium–hydrogen exchangers and sodium–bicarbonate co-transporters: ontogeny of protein expression in the rat brain

• Published in: Neuroscience 2001-01, Vol.102 (1), p.217-228
• Main Authors: Douglas, R.M, Schmitt, B.M, Xia, Y, Bevensee, M.O, Biemesderfer, D, Boron, W.F, Haddad, G.G
• Format: Article
• Language: English
• Subjects: Acid-Base Equilibrium - physiology; acid–base; Age Factors; Animals; bicarbonate; Biological and medical sciences; brain; Brain - growth & development; Brain - metabolism; Carrier Proteins - metabolism; development; Development. Senescence. Regeneration. Transplantation; Embryo, Mammalian; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental - physiology; Homeostasis - physiology; Hydrogen-Ion Concentration; Na@u+/HCO@d3@u; Neurons - cytology; Neurons - metabolism; protein expression; Protein Isoforms - metabolism; rat; Rats; Rats, Sprague-Dawley; Sodium-Bicarbonate Symporters; Sodium-Hydrogen Exchangers - metabolism; transporters; transporting ATPase; Vertebrates: nervous system and sense organs
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(00)00473-5

We used western blotting to examine the developmental profiles (at embryonic day 16 and postnatal days 1, 13, 23, 33 and 105) of protein expression for three sodium–hydrogen exchanger isoforms (1, 2 and 4) and for a sodium–bicarbonate co-transporter in three CNS regions (cortex, cerebellum and brainstem–diencephalon). In microsomal preparations, sodium–hydrogen exchanger isoform 1 and sodium–bicarbonate co-transporter protein expression in the CNS increases gradually from embryonic day 16 (25–40% of the adult level) to postnatal day 105. In contrast, sodium–hydrogen exchanger isoform 2 and 4 expression reaches a maximum (three to 20 times the adult level) at around three to four weeks of age. There is significant regional heterogeneity in the expression of sodium–hydrogen exchanger and sodium–bicarbonate co-transporter proteins in the rat CNS. Sodium–hydrogen exchanger isoform 1 was highly expressed in the brainstem–diencephalon, whereas the sodium–bicarbonate co-transporter was robustly expressed in the cerebellum and brainstem–diencephalon. These data indicate that the expression of sodium–hydrogen exchanger and sodium–bicarbonate co-transporter proteins varies as a function of both development and specific brain region.