The intestinal response to feeding in seawater gulf toadfish, Opsanus beta, includes elevated base secretion and increased epithelial oxygen consumption

J. R. Taylor, M. Groseil

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Intestinal HCO3- secretion is essential to marine teleost fish osmoregulation and comprises a considerable source of base efflux attributable to both serosal HCO3- and endogenous CO 2 hydration. The role of intestinal HCO3- secretion in dynamic acid-base balance regulation appears negligible in studies of unfed fish, but evidence of high intestinal fluid [HCO3 -] in fed marine teleosts led us to investigate the source of this HCO3- and its potential role in offsetting the postprandial 'alkaline tide' commonly associated with digestion. Specifically, we hypothesized that elevated metabolic rate and thus endogenous CO2 production by intestinal tissue as well as increased transepithelial intestinal HCO3- secretion occur post-feeding and offset a postprandial alkaline tide. To test these hypotheses changes in HCO 3- secretion and O2 consumption by gulf toadfish (Opsanus beta) isolated intestine were quantified 0, 3, 6,12, 24 and 48 h post-feeding. Intestinal tissue of unfed fish in general showed high rates of HCO3- secretion (15.5 μmol g-1 h -1) and O2 consumption (8.9μmol g-1 h -1). Furthermore, postprandial increases in both intestinal HCO 3- secretion and O2 consumption (1.6- and 1.9-fold peak increases, respectively) were observed. Elevated intestinal HCO3- secretion rates preceded and outlasted those of O2 consumption, and occurred at a magnitude and duration sufficient to account for the lack of alkaline tide. The dependence of these high rates of postprandial intestinal base secretion on serosal HCO3- indicates transepithelial HCO3- transport increases disproportionately more than endogenous CO2 production. The magnitude of postprandial intestinal HCO3- secretion indicates the intestine certainly is capable of postprandial acid-base balance regulation.

Original languageEnglish (US)
Pages (from-to)3873-3881
Number of pages9
JournalJournal of Experimental Biology
Volume212
Issue number23
DOIs
StatePublished - Dec 1 2009

Keywords

  • Acid-base balance regulation
  • Alkaline tide
  • Cl/HCO
  • NA/HCO cotransport
  • NBC
  • Postprandial, anion exchange

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Physiology
  • Insect Science
  • Aquatic Science

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