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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Physiol. | doi: 10.3389/fphys.2019.01334

Expression, localization, and effect of high salt intake on electroneutral Na+/HCO3– cotransporter NBCn2 in rat small intestine: implication in intestinal NaCl absorption

 Jin-Lin Wang1, Lei Zhao2, Jun Zhu1,  Deng-Ke Wang3,  Mei-Juan Ren1, Meng Wang1, Ying Liu1, Walter F. Boron3 and  Li-Ming Chen1*
  • 1Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology, China
  • 2Hubei Maternal and Child Health Hospital, China
  • 3Case Western Reserve University, United States

The electroneutral Na+/HCO3– cotransporter NBCn2 (SLC4A10) of solute carrier family 4 (SLC4) plays important physiological and pathological roles in the body. Our previous study showed that NBCn2 is expressed on the protein level in the small intestine of rat. Here, by reverse-transcription polymerase chain reaction, we identified a novel full-length NBCn2 variant, i.e., NBCn2-K, from rat small intestine. By pHi measurement with Xenopus oocytes, the activity of NBCn2-K is not significantly different from NBCn2-G. By western blotting, NBCn2 and the Na+/H+ exchanger NHE3 (SLC9A3) are predominantly expressed in the jejunum of rat small intestine. By immunofluorescence, NBCn2 and NHE3 are localized at the apical domain of the jejunum. NaCl overload decreases the expression of NBCn2 by 56% and that of NHE3 by 40% in the small intestine. We propose that NBCn2 is involved in the transepithelial NaCl absorption in the small intestine, and that the down-regulation of NBCn2 by NaCl represents an adaptive response to high salt intake in rat.

Keywords: HCO3- transporter, NaCl absorption, Epithelium, small intestine, High salt intake, Alternative Splicing

Received: 26 Jun 2019; Accepted: 07 Oct 2019.

Copyright: © 2019 Wang, Zhao, Zhu, Wang, Ren, Wang, Liu, Boron and Chen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mx. Li-Ming Chen, Huazhong University of Science and Technology, Key Laboratory of Molecular Biophysics of Ministry of Education, Wuhan, 430074, Hubei Province, China, liming.chen@hust.edu.cn