The putative mechanism of Nap>+ p> absorption in euryhaline elasmobranchs exists in the gills of a stenohaline marine elasmobranch, Squalus acanthias
详细信息 查看全文
- 作者：Keith P. Choe ; Susan L. Edwards ; James B. Claiborne ; David H. Evans
- 关键词：Osmoregulation ; Na
- 刊名：Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology
- 出版年：2007
- 出版时间：February 2007
- 年：2007
- 卷：146
- 期：2
- 页码：155-162
- 全文大小：1319 K
文摘
We recently cloned an NHE3 orthologue from the gills of the euryhaline Atlantic stingray (Dasyatis sabina), and generated a stingray NHE3 antibody to unequivocally localize the exchanger to the apical side of epithelial cells that are rich with Nap>+ p>/Kp>+ p>-ATPase (A MRC). We also demonstrated an increase in NHE3 expression when stingrays are in fresh water, suggesting that NHE3 is responsible for active Nap>+ p> absorption. However, the vast majority of elasmobranchs are only found in marine environments. In the current study, immunohistochemistry with the stingray NHE3 antibody was used to localize the exchanger in the gills of the stenohaline marine spiny dogfish shark (Squalus acanthias). NHE3 immunoreactivity was confined to the apical side of cells with basolateral Nap>+ p>/Kp>+ p>-ATPase and was excluded from cells with high levels of vacuolar Hp>+ p>-ATPase. Western blots detected a single protein of 88 kDa in dogfish gills, the same size as NHE3 in stingrays and mammals. These immunological data demonstrate that the putative cell type responsible for active Nap>+ p> absorption in euryhaline elasmobranchs is also present in stenohaline marine elasmobranchs, and suggest that the inability of most elasmobranchs to survive in fresh water is not due to a lack of the gill ion transporters for Nap>+ p> absorption.