TY - JOUR
T1 - Postprandial acid-base balance and ion regulation in freshwater and seawater-acclimated European flounder, Platichthys flesus
AU - Taylor, Josi R.
AU - Whittamore, Jonathan M.
AU - Wilson, Rod W.
AU - Grosell, Martin
N1 - Funding Information:
Acknowledgments This work was supported by Journal of Experimental Biology/Company of Biologists and Society for Experimental Biology travel fellowships and a University of Miami fellowship to JRT and by a National Science Foundation Grant to MG (NSF-IBN 0416440). JMW and RWW were supported by a BBSRC studentship and University of Exeter URF grant, respectively.
PY - 2007/8
Y1 - 2007/8
N2 - The effects of feeding on both acid-base and ion exchange with the environment, and internal acid-base and ion balance, in freshwater and seawater-acclimated flounder were investigated. Following voluntary feeding on a meal of 2.5-5% body mass and subsequent gastric acid secretion, no systemic alkaline tide or respiratory compensation was observed in either group. Ammonia efflux rates more than doubled from 489 ± 35 and 555 ± 64 μmol kg-1 h-1 under control conditions to 1,228 ± 127 and 1,300 ± 154 μmol kg-1 h-1 post-feeding in freshwater and seawater-acclimated fish, respectively. Based on predictions of gastric acid secreted during digestion, we calculated net postprandial internal base gains (i.e., HCO 3 - secreted from gastric parietal cells into the blood) of 3.4 mmol kg-1 in seawater and 9.1 mmol kg-1 in freshwater-acclimated flounder. However, net fluxes of ammonia, titratable alkalinity, Na+ and Cl- indicated that branchial Cl-/HCO 3 - and Na +/H+ exchange played minimal roles in counteracting these predicted base gains and cannot explain the absence of alkaline tide. Instead, intestinal Cl-/HCO 3 - exchange appears to be enhanced after feeding in both freshwater and seawater flounder. This implicates the intestine rather than the gills as a potential route of postprandial base excretion in fish, to compensate for gastric acid secretion.
AB - The effects of feeding on both acid-base and ion exchange with the environment, and internal acid-base and ion balance, in freshwater and seawater-acclimated flounder were investigated. Following voluntary feeding on a meal of 2.5-5% body mass and subsequent gastric acid secretion, no systemic alkaline tide or respiratory compensation was observed in either group. Ammonia efflux rates more than doubled from 489 ± 35 and 555 ± 64 μmol kg-1 h-1 under control conditions to 1,228 ± 127 and 1,300 ± 154 μmol kg-1 h-1 post-feeding in freshwater and seawater-acclimated fish, respectively. Based on predictions of gastric acid secreted during digestion, we calculated net postprandial internal base gains (i.e., HCO 3 - secreted from gastric parietal cells into the blood) of 3.4 mmol kg-1 in seawater and 9.1 mmol kg-1 in freshwater-acclimated flounder. However, net fluxes of ammonia, titratable alkalinity, Na+ and Cl- indicated that branchial Cl-/HCO 3 - and Na +/H+ exchange played minimal roles in counteracting these predicted base gains and cannot explain the absence of alkaline tide. Instead, intestinal Cl-/HCO 3 - exchange appears to be enhanced after feeding in both freshwater and seawater flounder. This implicates the intestine rather than the gills as a potential route of postprandial base excretion in fish, to compensate for gastric acid secretion.
KW - Alkaline tide
KW - Anion exchange
KW - Bicarbonate secretion
KW - Feeding
KW - Osmoregulation
UR - http://www.scopus.com/inward/record.url?scp=34547125314&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34547125314&partnerID=8YFLogxK
U2 - 10.1007/s00360-007-0158-3
DO - 10.1007/s00360-007-0158-3
M3 - Article
C2 - 17390137
AN - SCOPUS:34547125314
SN - 0174-1578
VL - 177
SP - 597
EP - 608
JO - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
JF - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
IS - 6
ER -