Title

Molecular Detection And Immunological Localization Of Gill Na +/H+ Exchanger In The Dogfish (Squalus Acanthias)

Keywords

Acid-base regulation; Branchial; Elasmobranch; Sodium/hydrogen antiporter

Abstract

The dogfish (Squalus acanthias) can make rapid adjustments to gill acid-base transfers to compensate for internal acidosis/alkalosis. Branchial Na+/H+ exchange (NHE) has been postulated as one mechanism driving the excretion of H+ following acidosis. We have cloned gill cDNA that includes an open reading frame coding for a 770-residue protein most homologous (∼71%) to mammalian NHE2. RT-PCR revealed NHE2 transcripts predominantly in gill, stomach, rectal gland, intestine, and kidney. In situ hybridization with an antisense probe against NHE2 in gill sections revealed a strong mRNA signal from a subset of interlamellar and lamellae cells. We developed dogfish-specific polyclonal antibodies against NHE2 that detected a ∼70-kDa protein in Western blots and immunologically recognized branchial cells having two patterns of protein expression. Cytoplasmic and apical NHE2 immunoreactivity were observed in cells coexpressing basolateral Na +-K+-ATPase. Other large ovoid cells more generally staining for NHE2 also were strongly positive for basolateral H +-ATPase. Gill mRNA levels for NHE2 and H+-ATPase did not change following systemic acidosis (as measured by quantitative PCR 2 h after a 1- or 2-meq/kg acid infusion). These data indicate that posttranslational adjustments of NHE2 and other transport systems (e.g., NHE3) following acidosis may be of importance in the short-term pH adjustment and net branchial H + efflux observed in vivo. NHE2 may play multiple roles in the gills, involved with H+ efflux from acid-secreting cells, basolateral H+ reabsorption for pHi regulation, and in parallel with H+-ATPase for the generation of HCO3- in base-secreting cells. Copyright © 2008 the American Physiological Society.

Publication Date

3-1-2008

Publication Title

American Journal of Physiology - Regulatory Integrative and Comparative Physiology

Volume

294

Issue

3

Number of Pages

-

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1152/ajpregu.00718.2007

Socpus ID

40449100385 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/40449100385

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