Developmental Aspects of Renal β-Amino Acid Transport. IV. Brush Border Membrane Response to Altered Intake of Sulfur Amino Acids

Chesney, Russell W.; Gusowski, Naomi; Theissen, Mary

doi:10.1203/00006450-198407000-00009

Cited by 25 publications

(10 citation statements)

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“…In contrast to uptake studies performed at taurine concentrations (10 pM) below the Km of the transport system [which is approximately 45 pM (5,9)], studies performed at 5 mM taurine showed no influence of age or diet. This concentration of taurine is approximately 10-fold higher than the Km value and is a level of substrate which is predominately transported by a Na+-independent diffusion process (9).…”

Section: Discussionmentioning

confidence: 75%

“…The renal adaptive response to altered sulfur amino acid intake involves a change in the initial rate (1 5-60 s) of taurine uptake by BBMV (5,6,9,10). This adaptive response is expressed for the low Km-high affinity portion of uptake (10-250 pM taurine concentration range), but not for the high Km-low affinity uptake site (0.5-5.0 mM taurine concentration range) (9,10).…”

Section: Discussionmentioning

confidence: 99%

“…Sprague-Dawley rats (King Laboratories, Fitchburg, WI) were used in all studies. Rats were fed one of three diets: LTD, NTD, or HTD prepared as described previously (5,11,12). Adult female rats were fed each diet from the point of impregnation (sperm positive vaginal smear).…”

Section: Methodsmentioning

confidence: 99%

“…Our lab has been concerned with those factors that contribute to the development of amino acid transport processes in the maturing animal and we hope to understand more fully whether maturation of the transport process can be accelerated by various physiologic manipulations (3-7). We have used as a transport probe, the p-amino acid, taurine, since one can manipulate the dietary intake of sulfur amino acids which results in a renal adaptive response for taurine (5,(8)(9)(10)(11)(12)(13).Full grown rats fed a limited sulfur amino acid intake reduce their urinary taurine excretion, a finding which is paralleled in vitro by augmented uptake of taurine by collagenase-isolated tubules (7) and by isolated brush border membrane vesicles (8,9). A diet consisting of normal amounts of methionine and 3% taurine causes hyperexcretions of taurine accompanied by diminished uptake of taurine by both tubules and vesicles.…”

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confidence: 99%

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confidence: 99%

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Development Aspects of Renal β-Amino Acid Transport. V Brush Border Membrane Transport in Nursing Animals—Effect of Age and Diet

et al. 1986

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ABSTRACT. This study examines the Na+-dependent accumulation of the &amino acid, taurine, by brush border membrane vesicles isolated from nursing animals compared to uptake in adult animals. The diets fed to the mothers nursing these pups were altered so as to provide a low sulfur amino acid intake or a high taurine diet as well as conventional sulfur amino acid intake. Taurinuria is greater in nursing animals than in adult controls, but animals of all ages respond to exposure to the low sulfur amino acid intake by conservation of taurine and to the high taurine diet by hyperexcretion of taurine. Taurine uptake at 10 pM by brush border membrane vesicles is influenced by age in all groups and by diet in 14-and 21-day-old animals. A precession of uptake is seen both in terms of initial and peak rate of uptake with the lowest values in 7-day-old animals to the highest in adult. Greater brush border membrane vesicle uptake is found in 14-and 21-day-old rats after exposure to the low sulfur amino acid intake and reduced uptake after the HTD, whereas no dietary influence on uptake was found in 7-day-old rats. Neither the pattern of the time course of uptake nor the uptake values at equilibrium (45 min) are affected by age or diet. Kinetic analyses of concentration dependent uptake show that the maturational process involves a change in the Vmax of initial uptake. Kinetic analysis of the adaptive response reveals an increase in Vmax after low sulfur amino acid intake and a decline after high taurine diet in 14-and 21-day-old pups, but not in 7-day-old pups. Uptakes at high taurine concentrations (5 mM) which are 10-fold higher than the Km are uninfluenced by age or diet. This study indicates that the physiologic taurinuria of immature rats may relate, in part, to a lower rate of uptake at the brush border surface, but that after 1 wk and before 2 wk of age the kidney can adapt to changes in sulfur amino acid intake. (Pediatr Res 202390-894,1986 The renal tubular epithelium is involved in the reabsorption of various ions and nutrients, including amino acids that arise by virtue of filtration across the glomerular basement membrane. A "physiologic" aminoaciduria is evident in the young of all mammalian species. On the surface, aminoaciduria seems inappropriate in view of the need for a young, rapidly growing animal to conserve compounds that are important in growth (I, 2). Our lab has been concerned with those factors that contribute to the development of amino acid transport processes in the maturing animal and we hope to understand more fully whether maturation of the transport process can be accelerated by various physiologic manipulations (3-7). We have used as a transport probe, the p-amino acid, taurine, since one can manipulate the dietary intake of sulfur amino acids which results in a renal adaptive response for taurine (5,(8)(9)(10)(11)(12)(13).Full grown rats fed a limited sulfur amino acid intake reduce their urinary taurine excretion, a finding which is paralleled in vitro by augmented uptake of taurine by c...

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Section: Discussionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Development Aspects of Renal β-Amino Acid Transport. V Brush Border Membrane Transport in Nursing Animals—Effect of Age and Diet

et al. 1986

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Development of β‐amino acid transport in the kidney

et al. 1988

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This study focuses on the maturation of the renal beta-amino acid transport system and uses dietary manipulation as a probe. The epithelial surface of the renal proximal tubule is responsible for the conservation of ions and organic solutes including beta-amino acids. This beta-amino acid transport system is stimulated during periods of reduced dietary intake and permits increased excretion following dietary excess. We have examined transport of the sulfur-containing beta-amino acid, taurine, as a measure of this renal adaptive response to fluctuations in dietary sulfur amino acid intake and as a substrate for the beta-amino acid transport system. A precession of taurine uptake values by brush border membrane vesicles (BBMV) prepared from nursing rats from youngest to oldest was evident. However, these membranes demonstrate the full renal adaptive response to altered sulfur amino acid intake after the first week of life. This adaptive response is expressed at the brush border surface by transport changes in both directions ("up regulation" and "down regulation"), through changes in the initial rate (15 sec) of Na+-taurine cotransport. No alterations in the lipid microenvironment of the membrane, as detected by altered membrane fluidity, were uncovered. Although vesicles from 7-day-old pups demonstrate adaptation and accumulate taurine to a limited extent, the accumulation of Na+, which energizes uptake, may be altered, thereby preventing full expression of the adaptive response and of transport capacity at this age.

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