Dietary adaptation of taurine transport by rat renal epithelium

Friedman, Aaron; Albright, Patti W.; Chesney, Russell W.

doi:10.1016/0024-3205(81)90478-1

Cited by 26 publications

(20 citation statements)

References 7 publications

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“…When the daily intake of the rats on the various diets was compared, there were no statistically significant differences among the groups (control 15 + 2 versus PfT-14.1 _+ 1.5 versus P-T' 13.5 f 1.7 versus P-T-14.8 f 1.6 g/d). This is different from the observation of Friedman et al (12), who reported that low taurine diets resulted in increased intake of food when compared with controls. On the day of the experiments, the rats were lightly anesthetized with anhydrous ether, blood was obtained from the bifurcation of the aorta, and the kidneys and ureters were checked for visible hydronephrosis and stone formation.…”

Section: Methodscontrasting

confidence: 99%

Adaptation to Taurine Deprivation in the Phosphate-Depleted Rat

1991

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ABSTRACT. The nonessential amino acid taurine, which is inert in renal tissue, was used to study renal adaptation in the presence of phosphate (P) depletion in the rat. Weanling rats were placed on the control diet (0.7% P, normal taurine) for 4 wk, then fed one of the experimental diets or continued on the control diet for 1 wk. The diets used were 1 ) P'T-(0.7% P, low taurine), 2) P-T+ (0.1% P, normal taurine); and 3) P-T-(0.1% P, low taurine). Taurine deficiency was associated with avid tubular reabsorption of taurine, irrespective of P status. This was associated with a 4-to 5-fold increase in the V,,, of uptake ( p < 0.001). On the other hand, P depletion increased the Km of taurine uptake by 6.6-to 9.5-fold, suggesting a decrease in the affinity of the taurine symport ( p < 0.001).This was independent of the taurine status of the animals. Although there was no effect of diet on the urinary excretion of 8-alanine, P depletion, irrespective of taurine status, resulted in a 2-fold increase in the Km of 8-alanine uptake. We conclude that the taurinuria of P depletion is reversed in taurine deprivation. The adaptive response involves an increase in the V,,, of uptake. However, the increase in Km of taurine uptake observed in P depletion does not reverse with taurine depletion. (Pediatr Res 30: 146-149, 1991) Abbreviations P, phosphorus BBMV, brush border membrane vesicle HEPES, N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid P+T-, phosphate replete, taurine-depleted P-T-, phosphate-and taurine-depleted P-T+, phosphate-depleted, taurine replete The renal tubular epithelium is able to conserve amino acids during periods of decreased dietary intake. Rats or mice fed diets low in sulfur-containing amino acids adapt by increasing the tubular reabsorption of these amino acids, particularly taurine (1, 2). The adaptive response manifests at the luminal surface by enhanced taurine uptake by BBMV prepared from rats fed these diets (3). These changes are associated with an increase in the initial rate of uptake (V,,,) rather than a decrease in the affinity of the symport (Km) (3). The physiologic signal(s) for the observed changes relate, in part, to alterations in the renal cortical content of taurine (4, 5). On the other hand, it has been shown that vitamin D-and/or phosphate-depleted rats develop taurinuria in the absence of secondary hyperparathyroidism (6). The taurinuria manifests at the renal brush border membrane by a decrease in the affinity of the taurine symport, resulting in decreased accumulation of taurine by BBMV (7). No changes could be elicited for the V,,, of uptake. In addition, the perturbation in uptake was not associated with alterations in plasma or renal cortex taurine concentrations, suggesting that overflow is not a regulatory signal in this model.Although the adaptive response has been shown to exist in terms of urinary excretion at the apical surface in adult rats, little is known about the response of these animals to taurine deprivation in the presence of phosphate depletion. Herein, we ...

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Section: Methodscontrasting

confidence: 99%

Adaptation to Taurine Deprivation in the Phosphate-Depleted Rat

1991

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“…Our laboratory has focused on physiologic factors that modify the development of amino acid transport systems in order to better understand the processes by which these transport sites achieve a mature transport profile (3)(4)(5)(6)(7). For an appropriate transport probe , we have used the l3-amino acid taurine, since it is relevant in the nutrition of young animals (8) and since one can manipulate the dietary level of sulfur amino acids to alter the renal handling of taurine (5,(9)(10)(11)(12)(13)(14). The Na"-dependent accumulation of taurine by BBMV isolated from nursing animals shows enhanced uptake in BBMV prepared from pups whose mothers art.…”

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confidence: 99%

Developmental Aspects of Renal β-Amino Acid Transport. VI. The Role of Membrane Fluidity and Phospholipid Composition in the Renal Adaptive Response in Nursing Animals

1987

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ABSTRACf. Accumulation of the fj-amino acid taurine is higher in adult rat renal brush border membrane vesicles than in nursing animals, which relates to a higher initial rate Vmax. A low sulfur amino acid diet increases and a 3% taurine diet reduces the Vmax of Nat-taurine cotransport in brush border membrane vesicles at all ages after 7 days as compared to values on a normal diet. To determine if changes in membrane fluidity account for these developmental and adaptive events, the fluorescent probe 1,6-diphenyl-l,3,5-hexatriene was used to measure fluorescence anisotropy. A two-component, single break curve fit the data over the range 4 to 56°C. Values for the break temperature centered around 23°C, not different than a break temperature determined in adult membranes. The values for membrane polarization range from 0.311 to 0.329 in membranes from 7-, 14-, and 21-day-old pups exposed to each of the three diets, significantly lower than the value in adult membranes (p < 0.02). The slopes of each component, equivalent to the apparent energy of activation, did not differ in relation to diet. The ontogenic changes in taurine uptake by brush border membrane vesicles related to the exposure to different dietary sulfur amino acid levels are not related to changes in membrane fluidity using 1,6-diphenyl-l,3,5-hexatriene as a probe. However, there is a decrease in fluidity with age. Total phospholipid content falls postweaning, and the percent of total content of phosphatidyl choline and glycerol phosphate fall, and phosphatidyl serine and ethanolamine rise as the rat ages. The results indicate that alterations in the phospholipid composition occur during the process of maturation and that changes in the fluidity of brush border membranes may account for maturational differences in Nat-dependent taurine transport. (Pediatr Res 22: 163-167,1987) Immature animals of virtually all mammalian species have a "physiologic" generalized aminoaciduria which results in excretion of a higher fraction of the filtered amino acid load of all amino acid classes (1,2). Our laboratory has focused on physiologic factors that modify the development of amino acid transport systems in order to better understand the processes by which these transport sites achieve a mature transport profile (3-7). For an appropriate transport probe , we have used the l3-amino acid taurine, since it is relevant in the nutrition of young animals (8) and since one can manipulate the dietary level of sulfur amino acids to alter the renal handling of taurine (5,9-14). The Na"-dependent accumulation of taurine by BBMV isolated from nursing animals shows enhanced uptake in BBMV prepared from pups whose mothers art. fed a LTD and reduced in membranes from pups fed a HTD when compared to membranes from pups whose dams were fed a NTO (15). Taurinuria is greater in nursing or weanling pups as compared to adult controls, but animals of all ages (7, 14, 21, 28 day and adult) respond to exposure to the LTO by urinary conservation of taurine and to the HTD by hyperexcre...

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“…Sodium, potassium, and phosphate are conserved when from these values, the diet is depleted of these ions (15,36,371, and the term renal NO attempt was made to pair-feed animals, but the animals adaptation is used to indicate this enhanced accumulation. More ingesting the LTD, which contained reduced methionine and Our laboratory (I4, 17,19) and lXozen (31,32) cysteine, consistently ingested more chow than all other groups. have shown that the 0-amino acid taurine is conserved by the ~~~~t ,~~ vesicle preparation, ~~~~l cortex brush border renal epithelium after ingestion of various diets that are deficient membrane vesicles were isolated by a series of differential tenin the sulfur-containing amino acids: methionine, cysteine, and trifugations using a modification of the method of ~~~~h and taurine.…”

Section: Abbreviationsmentioning

confidence: 64%