Active sulfate secretion by the intestine of winter flounder is through exchange for luminal chloride

SO2-4 transport by winter flounder intestine in Ussing chambers was characterized. With 50 mM SO2-4 (physiological level) bathing the lumen, net absorption (lumen to blood) dominated. Under short-circuited conditions, 1 mM SO2-4 on both sides, net active SO secretion occurred (8.55 plus or minus 0.9...

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Bibliographic Details
Published in:American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2003-02, Vol.53 (2), p.R380-R388
Main Authors: PELIS, Ryan M, RENFRO, J. Larry
Format: Article
Language:English
Subjects:
Biological and medical sciences
Digestive system
Fish
Fundamental and applied biological sciences. Psychology
Ions
Metabolisms and neurohumoral controls
Vertebrates: anatomy and physiology, studies on body, several organs or systems
Water and mineral metabolism. Osmoregulation. Acidobasic balance
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Summary:SO2-4 transport by winter flounder intestine in Ussing chambers was characterized. With 50 mM SO2-4 (physiological level) bathing the lumen, net absorption (lumen to blood) dominated. Under short-circuited conditions, 1 mM SO2-4 on both sides, net active SO secretion occurred (8.55 plus or minus 0.96 nmol . cm-2 . h-1). NaCN (10 mM), ouabain (10-4 M), and luminal DIDS (0.2 mM) inhibited net secretion. Removal of luminal Cl- and HCO-3 together (Cl--HCO-3) or Cl- alone blocked net secretion, whereas removal of luminal HCO-3 alone increased net secretion. SO2-4 uptake into foregut brush-border membrane vesicles was stimulated by a trans-Cl- gradient (in > out) and unaffected by a trans-HCO-3 gradient (in > out). Short-circuiting with K+ (in = out) and valinomycin had no effect on Cl--stimulated SO2-4 uptake, suggesting electroneutral exchange. Satiety (i.e., full stomach) stimulated the unidirectional absorptive flux, eliminating net secretion. It was concluded that the intestine is a site of SO2-4 absorption in marine teleosts and that active SO2-4 secretion is in exchange for luminal Cl-.
ISSN:0363-6119
1522-1490