Specificity of amino acid transport in renal papilla

Microinfusion of Henle's loops and vasa recta

William H Dantzler, Stefan Silbernagl

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18 Citations (Scopus)

Abstract

Amino acids can be reabsorbed distal to tips of Henle's loops and may be recycled between loops and vasa recta in rat papilla. Transport specificity was examined during continuous microinfusions of ascending Henle's loops and vasa recta with radiolabeled amino acids. Percent of recovered radiolabel as intact amino acid was also determined. Previous data indicated that, relative to simultaneously microinfused inulin, 30-40% of radiolabeled L- and D-Ala, L-Glu, L-Glu(NH2), and Gly, but no taurine (Tau) or mannitol, microinfused into Henle's loops was reabsorbed. In the present study, reabsorption was shown to involve intact L- and D-Ala, D-Glu, and L-Ser. L-Phe (50 mM) in infusate had no effect on reabsorption of L-Ala (2.5 mM) or L-Glu(NH2) (42.6 μM), and D-Asp (50 mM) had no effect on reabsorption of L-Glu (1.5 mM). Thus reabsorption from Henle's loops is not stereospecific, not different for neutral and acidic amino acids, and not inhibited by competitive inhibitors of proximal tubule amino acid transport, but it was not completely nonspecific and not a simple leak. Previous vasa recta microinfusions suggested that Ala could move directly from vasa recta to tubules. These studies were extended with simultaneous collections from ipsilateral and contralateral kidneys. Relative to simultaneously microinfused inulin, 40-50% of radiolabeled L-and D-Ala, L-Glu, and L-Glu(NH2) and 30% of L-Ser microinfused into ascending vasa recta appeared intact in urine from ipsilateral kidney, whereas only 1-3% appeared in urine from contralateral kidney. Fifty percent of infused D-Glu was excreted intact by each kidney; 70% of infused Tau was excreted intact by ipsilateral kidney, and 22% was excreted by contralateral kidney. L-Phe (50 mM) in infusate inhibited appearance of L-Ala (2.5 mM) and D-Ala (10 mM) but not L-Glu(NH2) (42.6 μM) in ipsilateral urine. D-Asp (50 mM) inhibited appearance of L-Glu (1.5 mM), and β-Ala (50 mM) inhibited appearance of Tau (78 μM) in ipsilateral urine. Thus some amino acids can move directly from vasa recta into tubules (probably descending thin limbs of Henle's loops) by a process showing significant specificity.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume261
Issue number3 30-3
StatePublished - 1991

Fingerprint

Loop of Henle
Rectum
Kidney
Amino Acids
Taurine
Urine
Inulin
Acidic Amino Acids
Neutral Amino Acids
Mannitol

Keywords

  • Amino acid recycling
  • D-alanine
  • D-glutamate
  • Glycine
  • L-alanine
  • L-glutamate
  • L-glutamine
  • L-serine
  • Rat papilla
  • Taurine

ASJC Scopus subject areas

  • Physiology

Cite this

@article{a50eb25f85fd459c86ec9563f8ad5e66,
title = "Specificity of amino acid transport in renal papilla: Microinfusion of Henle's loops and vasa recta",
abstract = "Amino acids can be reabsorbed distal to tips of Henle's loops and may be recycled between loops and vasa recta in rat papilla. Transport specificity was examined during continuous microinfusions of ascending Henle's loops and vasa recta with radiolabeled amino acids. Percent of recovered radiolabel as intact amino acid was also determined. Previous data indicated that, relative to simultaneously microinfused inulin, 30-40{\%} of radiolabeled L- and D-Ala, L-Glu, L-Glu(NH2), and Gly, but no taurine (Tau) or mannitol, microinfused into Henle's loops was reabsorbed. In the present study, reabsorption was shown to involve intact L- and D-Ala, D-Glu, and L-Ser. L-Phe (50 mM) in infusate had no effect on reabsorption of L-Ala (2.5 mM) or L-Glu(NH2) (42.6 μM), and D-Asp (50 mM) had no effect on reabsorption of L-Glu (1.5 mM). Thus reabsorption from Henle's loops is not stereospecific, not different for neutral and acidic amino acids, and not inhibited by competitive inhibitors of proximal tubule amino acid transport, but it was not completely nonspecific and not a simple leak. Previous vasa recta microinfusions suggested that Ala could move directly from vasa recta to tubules. These studies were extended with simultaneous collections from ipsilateral and contralateral kidneys. Relative to simultaneously microinfused inulin, 40-50{\%} of radiolabeled L-and D-Ala, L-Glu, and L-Glu(NH2) and 30{\%} of L-Ser microinfused into ascending vasa recta appeared intact in urine from ipsilateral kidney, whereas only 1-3{\%} appeared in urine from contralateral kidney. Fifty percent of infused D-Glu was excreted intact by each kidney; 70{\%} of infused Tau was excreted intact by ipsilateral kidney, and 22{\%} was excreted by contralateral kidney. L-Phe (50 mM) in infusate inhibited appearance of L-Ala (2.5 mM) and D-Ala (10 mM) but not L-Glu(NH2) (42.6 μM) in ipsilateral urine. D-Asp (50 mM) inhibited appearance of L-Glu (1.5 mM), and β-Ala (50 mM) inhibited appearance of Tau (78 μM) in ipsilateral urine. Thus some amino acids can move directly from vasa recta into tubules (probably descending thin limbs of Henle's loops) by a process showing significant specificity.",
keywords = "Amino acid recycling, D-alanine, D-glutamate, Glycine, L-alanine, L-glutamate, L-glutamine, L-serine, Rat papilla, Taurine",
author = "Dantzler, {William H} and Stefan Silbernagl",
year = "1991",
language = "English (US)",
volume = "261",
journal = "American Journal of Physiology",
issn = "0363-6143",
publisher = "American Physiological Society",
number = "3 30-3",

}

TY - JOUR

T1 - Specificity of amino acid transport in renal papilla

T2 - Microinfusion of Henle's loops and vasa recta

AU - Dantzler, William H

AU - Silbernagl, Stefan

PY - 1991

Y1 - 1991

N2 - Amino acids can be reabsorbed distal to tips of Henle's loops and may be recycled between loops and vasa recta in rat papilla. Transport specificity was examined during continuous microinfusions of ascending Henle's loops and vasa recta with radiolabeled amino acids. Percent of recovered radiolabel as intact amino acid was also determined. Previous data indicated that, relative to simultaneously microinfused inulin, 30-40% of radiolabeled L- and D-Ala, L-Glu, L-Glu(NH2), and Gly, but no taurine (Tau) or mannitol, microinfused into Henle's loops was reabsorbed. In the present study, reabsorption was shown to involve intact L- and D-Ala, D-Glu, and L-Ser. L-Phe (50 mM) in infusate had no effect on reabsorption of L-Ala (2.5 mM) or L-Glu(NH2) (42.6 μM), and D-Asp (50 mM) had no effect on reabsorption of L-Glu (1.5 mM). Thus reabsorption from Henle's loops is not stereospecific, not different for neutral and acidic amino acids, and not inhibited by competitive inhibitors of proximal tubule amino acid transport, but it was not completely nonspecific and not a simple leak. Previous vasa recta microinfusions suggested that Ala could move directly from vasa recta to tubules. These studies were extended with simultaneous collections from ipsilateral and contralateral kidneys. Relative to simultaneously microinfused inulin, 40-50% of radiolabeled L-and D-Ala, L-Glu, and L-Glu(NH2) and 30% of L-Ser microinfused into ascending vasa recta appeared intact in urine from ipsilateral kidney, whereas only 1-3% appeared in urine from contralateral kidney. Fifty percent of infused D-Glu was excreted intact by each kidney; 70% of infused Tau was excreted intact by ipsilateral kidney, and 22% was excreted by contralateral kidney. L-Phe (50 mM) in infusate inhibited appearance of L-Ala (2.5 mM) and D-Ala (10 mM) but not L-Glu(NH2) (42.6 μM) in ipsilateral urine. D-Asp (50 mM) inhibited appearance of L-Glu (1.5 mM), and β-Ala (50 mM) inhibited appearance of Tau (78 μM) in ipsilateral urine. Thus some amino acids can move directly from vasa recta into tubules (probably descending thin limbs of Henle's loops) by a process showing significant specificity.

AB - Amino acids can be reabsorbed distal to tips of Henle's loops and may be recycled between loops and vasa recta in rat papilla. Transport specificity was examined during continuous microinfusions of ascending Henle's loops and vasa recta with radiolabeled amino acids. Percent of recovered radiolabel as intact amino acid was also determined. Previous data indicated that, relative to simultaneously microinfused inulin, 30-40% of radiolabeled L- and D-Ala, L-Glu, L-Glu(NH2), and Gly, but no taurine (Tau) or mannitol, microinfused into Henle's loops was reabsorbed. In the present study, reabsorption was shown to involve intact L- and D-Ala, D-Glu, and L-Ser. L-Phe (50 mM) in infusate had no effect on reabsorption of L-Ala (2.5 mM) or L-Glu(NH2) (42.6 μM), and D-Asp (50 mM) had no effect on reabsorption of L-Glu (1.5 mM). Thus reabsorption from Henle's loops is not stereospecific, not different for neutral and acidic amino acids, and not inhibited by competitive inhibitors of proximal tubule amino acid transport, but it was not completely nonspecific and not a simple leak. Previous vasa recta microinfusions suggested that Ala could move directly from vasa recta to tubules. These studies were extended with simultaneous collections from ipsilateral and contralateral kidneys. Relative to simultaneously microinfused inulin, 40-50% of radiolabeled L-and D-Ala, L-Glu, and L-Glu(NH2) and 30% of L-Ser microinfused into ascending vasa recta appeared intact in urine from ipsilateral kidney, whereas only 1-3% appeared in urine from contralateral kidney. Fifty percent of infused D-Glu was excreted intact by each kidney; 70% of infused Tau was excreted intact by ipsilateral kidney, and 22% was excreted by contralateral kidney. L-Phe (50 mM) in infusate inhibited appearance of L-Ala (2.5 mM) and D-Ala (10 mM) but not L-Glu(NH2) (42.6 μM) in ipsilateral urine. D-Asp (50 mM) inhibited appearance of L-Glu (1.5 mM), and β-Ala (50 mM) inhibited appearance of Tau (78 μM) in ipsilateral urine. Thus some amino acids can move directly from vasa recta into tubules (probably descending thin limbs of Henle's loops) by a process showing significant specificity.

KW - Amino acid recycling

KW - D-alanine

KW - D-glutamate

KW - Glycine

KW - L-alanine

KW - L-glutamate

KW - L-glutamine

KW - L-serine

KW - Rat papilla

KW - Taurine

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M3 - Article

VL - 261

JO - American Journal of Physiology

JF - American Journal of Physiology

SN - 0363-6143

IS - 3 30-3

ER -