Molecular detection and immunological localization of gill Na+/H+ exchanger in the dogfish (Squalus acanthias).

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 (approximately 71%) to mammalian NHE2.

The effect of environmental hypercapnia and salinity on the expression of NHE-like isoforms in the gills of a euryhaline fish (Fundulus heteroclitus).

The current models for branchial acid excretion in fishes include Na(+)/H(+) exchange and the electrogenic excretion of H+ via H+-ATPase. The predominant route of acid excretion in some freshwater fishes is thought to be via the H+-ATPase/Na+ channel system. The euryhaline Fundulus heteroclitus may not fit this profile even when adapted to freshwater (FW).