Renal Tubular Transport of Amino Acids

1971 ◽  
Vol 17 (4) ◽  
pp. 245-266 ◽  
Author(s):  
John Atherton Young ◽  
Benedict Sol Freedman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Proximal Tubule ◽  
Amino Nitrogen ◽  
High Capacity ◽  
High Specificity ◽  
Brush Borders ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Renal Tubular

Abstract Cushny in 1917 first remarked on the extensive amino acid reabsorption which occurs in the nephron. Although many workers since then have studied the nature and localization of the reabsorptive mechanism, progress has been slow because of the technical difficulties of micropuncture work. The bulk of filtered amino nitrogen is reabsorbed in the proximal tubule although the possibility of there being more distal reabsorptive (or secretory) sites cannot be excluded. It is also uncertain whether all segments of the proximal tubule contribute equally to the reabsorptive process. Amino acid reabsorption is an active process involving numerous illdefined steps, the first of which is binding to the brush borders. Renal amino acid transport mechanisms are of two kinds: the high-capacity low-specificity systems transport whole groups of amino acids—the acidic, basic, neutral, and imino-glycine groups—while the other, the low-capacity high-specificity systems, transport single or perhaps pairs of amino acids only.

Interactions of neutral and acidic amino acids in renal tubular transport

1962 ◽  
Vol 202 (3) ◽  
pp. 577-583 ◽  
Author(s):  
William A. Webber
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Concentrations ◽  
Side Chain ◽  
Neutral Amino Acids ◽  
Acidic Amino Acids ◽  
Renal Tubular Reabsorption ◽  
Renal Tubular Transport ◽  
Renal Tubular ◽  
Amino Acid Concentrations

The effects of intravenous infusions of a variety of neutral and acidic amino acids on the plasma concentrations and excretions of naturally occurring amino acids were studied in dogs. Conventional clearance techniques were used, and the amino acid concentrations were determined by ion exchange column chromatography. Infusion of either l-glutamic acid or l-aspartic acid caused a gross increase in the plasma concentration and excretion of the other. Infusions of neutral amino acids including glycine, l-alanine, l-leucine, l-methionine, l-proline, and l-phenylalanine caused some minor changes in the endogenous plasma amino acid concentrations. They produced increases in the excretion of other neutral amino acids and, in some cases, of acidic and basic amino acids as well. In general, amino acids with long side chains were most effective in inhibiting reabsorption while cyclic side-chain compounds were less effective. There appear to be at least three somewhat separable mechanisms for renal tubular reabsorption of amino acids in dogs.

Renal mechanism for excretion and transformation of arsenic in the dog

1965 ◽  
Vol 208 (5) ◽  
pp. 832-840 ◽  
Author(s):  
Jack M. Ginsburg
Keyword(s):  
Proximal Tubule ◽  
Tubular Reabsorption ◽  
Major Site ◽  
Net Production ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Arsenic Transport ◽  
Renal Tubular ◽  
Stop Flow ◽  
Subsequent Diffusion

Studies have been performed in female dogs on the renal tubular transport of arsenate and arsenite and on the intrarenal conversion of arsenate to arsenite. During the infusion of arsenate there is a net reabsorption of arsenate and a net secretion of arsenite. The rate of arsenite secretion varies directly with the rate of arsenate reabsorption. The transport of both ions is inhibited by phosphate and glucose. Renal arteriovenous concentration differences show a net production of arsenite from arsenate. Stop-flow studies localize the major site of arsenic transport in the proximal tubule. During arsenite infusion both arsenate and arsenite undergo net reabsorption. The data are interpreted as representative of a tubular reabsorption of arsenate with intracellular conversion of arsenate to arsenite and subsequent diffusion of arsenite across both luminal and antiluminal faces of the tubular cell.

Renal tubular transport of water, solute, and PAH in rats loaded with isotonic saline

1965 ◽  
Vol 209 (6) ◽  
pp. 1199-1205 ◽  
Author(s):  
Marshall A. Cortney ◽  
Margaret Mylle ◽  
William E. Lassiter ◽  
Carl W. Gottschalk
Keyword(s):  
Proximal Tubule ◽  
Isotonic Saline ◽  
Urine Flow ◽  
Water Reabsorption ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Pah Clearance ◽  
Renal Tubular ◽  
Proximal Convolution ◽  
Filtered Load

Renal tubular transport of water, osmotically active solute, and PAH were studied with micropuncture methods in anesthetized rats loaded with a volume of 0.9% sodium chloride solution equivalent to 10% of their body weight. Inulin clearance and urine flow were greatly elevated above values in nondiuretic animals, but there was little change in PAH clearance. F/P inulin-C14OOH ratios indicated that 42% of the filtered water and solute was reabsorbed along the proximal convolution, a lower fraction than is found in nondiuretic and hypertonic saline-loaded rats. This indicates that the rate of solute and water reabsorption in the proximal tubule did not increase in proportion to the increased filtered load, and it was, in fact, similar to that in nondiuretic rats. Intravenous administration of vasopressin and aldosterone had no demonstrable effects on solute or water reabsorption. F/P PAH/inulin ratios demonstrated that PAH secretion occurred along the proximal tubule, but probably in no other portion of the nephron.

Renal tubular transport of nitrofurantoin

1962 ◽  
Vol 202 (6) ◽  
pp. 1136-1140 ◽  
Author(s):  
James A. Buzard ◽  
Raymond C. Bender ◽  
Esther G. Nohle ◽  
Donald T. Humphrey ◽  
Mary F. Paul
Keyword(s):  
Proximal Tubule ◽  
Transport System ◽  
Weak Acid ◽  
Tubular Secretion ◽  
Acid Transport ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Renal Tubular

Tubular secretion of nitrofurantoin has been demonstrated in the dog and the chicken. This secretion has been localized in the proximal tubule and has been shown to be due to the action of the weak acid transport system. Reabsorption of nitrofurantoin by passive, nonionic diffusion has also been illustrated.

scholarly journals Regulation of glomerular and proximal tubule renin mRNA by chronic changes in dietary NaCl

1997 ◽  
Vol 273 (6) ◽  
pp. F892-F898 ◽  
Author(s):  
Julia E. Tank ◽  
William L. Henrich ◽  
Orson W. Moe
Keyword(s):  
Proximal Tubule ◽  
Extracellular Fluid ◽  
Renin Angiotensin System ◽  
Proximal Tubules ◽  
Angiotensin System ◽  
Tubular Transport ◽  
Renin Mrna ◽  
Renal Tubular Transport ◽  
Polymerase Chain ◽  
Renal Tubular

Renal adaptations to chronic changes in dietary NaCl and extracellular fluid volume involve both glomerular and tubular mechanisms that result in preservation of glomerular filtration rate and modifications of renal tubular transport to secure external NaCl balance. Although the systemic renin-angiotensin system (RAS) mediates some of these responses, the possible contributions of local glomerular and proximal tubule RASs in these adaptations have not been examined. Thus, in this study, glomeruli and proximal tubules were microdissected from rats adapted to high (4.0%)-, normal (0.5%), or low (0.01%)-NaCl diets, and renin mRNA was measured using quantitative competitive reverse transcription-polymerase chain reaction. After 4 days of the diets, glomerular renin mRNA abundance was increased 100% by the low-NaCl diet ( P < 0.05) and suppressed 50% ( P < 0.01) by the high-NaCl diet compared with controls. Renin mRNA in proximal tubules was stimulated 230% ( P < 0.05) by the low-NaCl diet and tended to be suppressed (68% decrease, not significant) by the high-NaCl diet. When the high-NaCl diet was continued for 2 wk, proximal tubule renin mRNA was suppressed by 89% ( P < 0.05). This study provides evidence that glomerular and proximal tubule renin transcript levels are regulated by chronic changes in dietary NaCl, suggesting that local RASs contribute to the renal adaptations in response to chronic alterations in NaCl.

Interactions of amino acids in renal tubular transport

1961 ◽  
Vol 200 (2) ◽  
pp. 380-386 ◽  
Author(s):  
W. A. Webber ◽  
J. L. Brown ◽  
R. F. Pitts
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Fold Increase ◽  
Basic Amino Acid ◽  
Arginine Infusion ◽  
Naturally Occurring ◽  
Renal Tubular Transport ◽  
Renal Tubular ◽  
Amino Acid Concentrations ◽  
Slight Depression

The effects of intravenous infusions of l-lysine, l-arginine, l-histidine, l-ornithine and l-cysteine at three rates on the plasma levels and excretions of naturally occurring amino acids were studied in dogs. Conventional clearance techniques were used, and the amino acid concentrations in both plasma and urine were determined by column chromatography. A number of changes were observed in plasma amino acid concentrations, the most striking of which was a 20-fold increase in ornithine following arginine infusion. This increase is probably the result of conversion of arginine to ornithine via the Krebs-Henseleit cycle. Lysine, ornithine, arginine and cystine or cysteine showed marked mutual inhibition of tubular reabsorption. Histidine modestly inhibited reabsorption of these amino acids, and in turn its reabsorption was modestly depressed by them. The basic amino acid infusions also caused modest depression of the reabsorption of glycine and slight depression of that of several other amino acids. The reabsorptive mechanisms for lysine, arginine, ornithine and cystine are closely related and may be identical. There is, however, minor reabsorptive competition between these amino acids and certain others, suggesting that the mechanisms are not completely specific.

MATHEMATICAL MODELS FOR THE SYNTHESIS OF PLANT-BASED COMPOSITIONS WITH IMPROVED AMINO ACID COMPOSITION

2021 ◽  
Author(s):  
Irina Gaivoronskaya ◽  
Valenitna Kolpakova
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Mathematical Models ◽  
Functional Properties ◽  
Amino Nitrogen ◽  
Essential Amino Acids ◽  
Major Allergen ◽  
Structural Features ◽  
Covalent Bonds ◽  
Pea Protein

The aim of the work was to optimize the process of obtaining multicomponent protein compositions with high biological value and higher functional properties than the original vegetable protein products. Was realized studies to obtain biocomposites on the base of pea protein-oat protein and pea protein-rice protein. Developed composites were enriched with all limited amino acids. For each of the essential amino acids, the amino acid score was 100% and higher. Protein products used in these compositions are not in major allergen list, which allows to use these compositions in allergen-free products and specialized nutrition. To determine biosynthesis parameters for compositions from pea protein and various protein concentrates with the use of transglutaminase enzyme, was studied effect of concentration and exposition time on the amount of amino nitrogen released during the reaction. Decreasing of amino nitrogen in the medium indicated the occurrence of a protein synthesis reaction with the formation of new covalent bonds. Were determined optimal parameters of reaction: the hydromodule, the exposure time, the concentration of EP of the preparation, were obtained mathematical models. Studies on the functional properties of composites, the physicochemical properties of the proteins that make up their composition, and structural features will make it possible to determine the uses in the manufacture of food products based on their ability to bind fat, water, form foam, gels, and etc.

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