Renal sugar transport in the winter flounder: V. secretion of 2-deoxy-D-galactose.
Isolated renal tubules and renal clearance techniques were used to characterize the renal handling of 2-deoxy-D-galactose (2-d-Gal) by the winter flounder (Pseudopleuronectes americanus). In vitro, energy-dependent, pH-sensitive uptake of 2-d-Gal (2-100 micron) was seen at the antiluminal face of the cell. Clearance measurements showed net secretion of 2-d-Gal in vivo. The mean clearance of 2-d-Gal in 18 fish was 0.98 +/- 0.16 ml/h while the glomerular filtration rate (GFR) was only 0.37 +/- 0.10 ml/h. Secretion was associated with marked renal accumulation of both 2-d-Gal and phosphorylated derivatives (2-d-Gal-1-phosphate). Tissue-to-plasma ratios (T/P) averaged 19 for free sugar and 59 for total sugar. Both clearance ratio and T/P were reduced to approximately 1 by injection of galactose (2.5 mmol/kg) simultaneously with 2-d-Gal (25 mumol/kg). Phlorizin (2.5 mumol/kg) increased net 2-d-Gal secretion, whereas glucose (2.5 mmol/kg) produced no change in secretion. Both compounds depressed 2-d-Gal T/P. This result suggests the presence of readsorptive transport at the brush border, sensitive to glucose and phlorizin.
D000693:Anaerobiosis; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D004140:Dinitrophenols / Q000494:pharmacology; D005399:Fishes / Q000378:metabolism*; D005643:Fucose / Q000378:metabolism*; D005690:Galactose / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007684:Kidney Tubules / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D009994:Osmolar Concentration; D010695:Phlorhizin / Q000494:pharmacology; D011339:Probenecid / Q000494:pharmacology
D004140:Dinitrophenols; D005643:Fucose; D010695:Phlorhizin; D005947:Glucose; D011339:Probenecid; D005690:Galactose