A critical analysis of transepithelial potential in intact killifish (Fundulus heteroclitus) subjected to acute and chronic changes in salinity

Chris M. Wood, Martin Grosell

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


We investigated the in vivo salinity-dependent behavior of transepithelial potential (TEP) in Fundulus heteroclitus (3-9 g) using indwelling coelomic catheters, a technique which was validated against blood catheter measurements in a larger species (Opsanus beta; 35-70 g). In seawater (SW)-acclimated killifish, TEP was +23 mV (inside positive), but changed to -39 mV immediately after transfer to freshwater (FW). Acute transfer to dilute salinities produced a TEP profile, which rapidly attenuated as salinity increased (0, 2.5, 5 and 10% SW), with cross-over to positive values between 20 and 40% SW, and a linear increase thereafter (60, 80 and 100% SW). TEP response profiles were also recorded after acute transfer to comparable dilutions of 500 mmol L-1 NaCl, NaNO3, Na gluconate, choline chloride, N-methyl-d-glutamate (NMDG) chloride, or 1,100 mosmol kg-1 mannitol. These indicated high non-specific cation permeability and low non-specific anion permeability without influence of osmolality in SW-acclimated killifish. While there was a small electrogenic component in high salinity, a Na+ diffusion potential predominated at all salinities due to the low P Cl/P Na (0.23) of the gills. The very negative TEP in FW was attenuated in a linear fashion by log elevations in [Ca2+] such that PCl/P Na increased to 0.73 at 10 mmol L-1. SW levels of [K +] or [Mg2+] also increased the TEP, but none of these cations alone restored the positive TEP of SW-acclimated killifish. The very negative TEP in FW attenuated over the first 12 h of exposure and by 24-30 h reached +3 mV, representative of long-term FW-acclimated animals; this reflected a progressive increase in P Cl/P Na from 0.23 to 1.30, probably associated with closing of the paracellular shunt pathway. Thereafter, the TEP in FW-acclimated killifish was unresponsive to [Ca2+] (also to [K+], [Mg2+], or chloride salts of choline and NMDG), but became more positive at SW levels of [Na+]. Killifish live in a variable salinity environment and are incapable of gill Cl- uptake in FW. We conclude that the adaptive significance of the TEP patterns is that changeover to a very negative TEP in FW will immediately limit Na+ loss while not interfering with active Cl- uptake because there is none. Keeping the shunt permeability high for a few hours means that killifish can return to SW and instantaneously re-activate their NaCl excretion mechanism.

Original languageEnglish (US)
Pages (from-to)713-727
Number of pages15
JournalJournal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
Issue number6
StatePublished - Aug 2008


  • Calcium-dependent potential
  • Diffusion potential
  • Electrogenic potential
  • Gill permeability
  • Opsanus beta
  • P/P ratio
  • TEP

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Environmental Science(all)
  • Physiology
  • Physiology (medical)

Fingerprint Dive into the research topics of 'A critical analysis of transepithelial potential in intact killifish (Fundulus heteroclitus) subjected to acute and chronic changes in salinity'. Together they form a unique fingerprint.

Cite this