Salt balance in embryos of Fundulus heteroclitus and F. bermudae adapted to seawater

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22Na+ and 36Cl- tracer flux experiments of embryos of Fundulus heteroclitus show that a significant influx and efflux of Na+ and Cl- occur during development. The average influx for Na+ and Cl-, respectively, are 5.0 ± 0.76 and 1.1 ± 0.1 nmol/mg-1/h-1. The average effluxes are 4.9 ± 0.95 and 3.0 ± 0.01 nmol/mg-1/h-1 for Na+ and Cl-, respectively. The electrical potential across the embryonic cavity epithelium of F. heteroclitus and F. bermudae is 50 ± 1.7 mV and 40 ± 1.3 mV, respectively (inside positive). Diluting the artificial seawater bathing medium with distilled water decreases the potential across the embryonic cavity of F. bermudae to -11 ± 5.0 mV at 5% artificial seawater. Because in seawater the potential across the embryonic cavity epithelium is inside positive, the efflux of Cl- is against its electrical potential gradient indicating an active extrusion mechanism for Cl-. The site of the active extrusion mechanism for chloride is located in the yolk sac where chloride cells associated with blood vessels are common.

Original languageEnglish (US)
Pages (from-to)R42-R49
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number1
StatePublished - Jan 1 1980


ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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