Characterization of Na+ uptake in the endangered desert pupfish, Cyprinodon macularius (Baird and Girard)

Kevin V. Brix, Martin Grosell

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

This study provided an initial characterization of Na+ uptake in saline freshwater by the endangered pupfish, Cyprinodon macularius. This species occurs only in several saline water systems in the southwestern USA and northern Mexico, where salinity is largely controlled by water-management practices. Consequently, understanding the osmoregulatory capacity of this species is important for their conservation. The lower acclimation limit of C. macularius in freshwater was found to be 2 mM Na+. Fish acclimated to 2 or 7 mM Na+ displayed similar Na+ uptake kinetics, with Km values of 4321 and 3672 μM and Vmax values of 4771 and 3602 nmol g-1 h-1, respectively. A series of experiments using pharmacological inhibitors indicated that Na+ uptake in C. macularius was not sensitive to bumetanide, metolazone, or phenamil. These results indicate the Na+- K+-2Cl- cotransporter, Na+-Cl- cotransporter, and the Na+ channel-H+-ATPase system are likely not to be involved in Na+ uptake at the apical membrane of fish gill ionocytes in fish acclimated to 2 or 7 mM Na+. However, Na+ uptake was sensitive to 1 × 10-3 M amiloride (not 1 × 10-4 or 1 × 10-5 M), 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), and ethoxzolamide. These data suggest that C. macularius relies on a low-affinity Na+-H+ exchanger for apical Na+ uptake and that H+ ions generated via carbonic anhydrase-mediated CO2 hydration are important for the function of this protein.

Original languageEnglish (US)
Article numbercot005
JournalConservation Physiology
Volume1
Issue number1
DOIs
StatePublished - 2013
Externally publishedYes

Fingerprint

Killifishes
Fishes
desert
Fresh Water
Ethoxzolamide
Metolazone
Member 3 Solute Carrier Family 12
fish
Bumetanide
Sodium-Hydrogen Antiporter
Proton-Translocating ATPases
Carbonic Anhydrases
Amiloride
Acclimatization
Practice Management
Salinity
Mexico
hydration
acclimation
water management

Keywords

  • Carbonic anhydrase
  • Cyprinodon macularius
  • Na-H exchanger
  • Osmoregulation

ASJC Scopus subject areas

  • Nature and Landscape Conservation
  • Management, Monitoring, Policy and Law
  • Ecological Modeling
  • Physiology

Cite this

Characterization of Na+ uptake in the endangered desert pupfish, Cyprinodon macularius (Baird and Girard). / Brix, Kevin V.; Grosell, Martin.

In: Conservation Physiology, Vol. 1, No. 1, cot005, 2013.

Research output: Contribution to journalArticle

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