Intestinal Uptake of Valine in Obesity

Steiner, M; Bourges, Héctor; Farrish, Grover C. M.; Ross, J. R.; Gray, Seymour J.

doi:10.1097/00000441-196904000-00004

Cited by 6 publications

(2 citation statements)

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“…In the present in vivo study the Michealis transport constant was 4.2-5.5 mM for the segments of suckling, weanling and adolescent rats. In biopsies of the small intestine obtained from adult humans the apparent K, values for absorption of valine was found to be 9.1 mM in obese subjects and 4.6 in normal subjects (9). Again values close to those found in the present in vivo and in the previous in vitro rat studies.…”

supporting

confidence: 89%

Maturation of the Small Intestine: Absorption of L-Valine in Rats

Younoszai

Komnick

1982

Pediatr Res

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Summary studies comparing absorption of L-valine in pieces of the smallThe in vivo absorption of L-valme was studied in segments of the jejunum and ileum using a one-pass perfusion technique in normal suckling (Zweek-old), weanling (3-week-old) and adolescent (dweek-old) rats. In both the jejunum and the ileum, rate of absorption (pmoles/h/g wt) of L-valine declined with age. The relationship between absorption rate and luminal concentration suggested the presence both of a saturable carrier mediated (Jmax[CI/Kt + [C]) and diffusive (KD* [C]) processes for absorption of L-valine. In both the jejunum and the ileum, rates ' of carrier mediated and of diffusive absorption of L-valine were over &fold greater in the sucklimg than in the adolescent rats. Rates of absorption were not significantly different in the jejunum and ileum at all three age periods. Although values of J,, and KD were greater in segments of the suckling rats, values of the apparent Kt were similar at all 3 age periods, suggesting that the mechanism (affinity of the carrier macromolecules) of carrier mediated absorption of L-valine did not change with age but the passive permeability of the intestinal muc&a to L-valine and relative number of L-valine absorbing sites (number of carrier -macromolecules) decreased per unit weight of intestine with increasing age. Serum and intestinal tissue concentration of L-valine at the end of the perfusion period were greater in the Zweek-old than in the older rats. After parentral injection of [14C1-~-valine rate of secretion of L-valine was several-fold greater in the jejunum and the ileum of the suckling than of the adolescent rats. SpeculationThe decline in the ability of the small intestine to absorb Lvaline (per unit weight) with increasing age appears to be due to a decrease in the passive permeability of the mucosal membrane to L-valine as well as to a relative decrease in the number of absorbing sites (carrier macromolecules) per unit weight of intestine. The decline in the passive permeability suggests a change in the biochemical composition or the ultrastructure of the mucosal membrane during maturation. The decline in the absorbing capacity of the small intestine with age could be due to a relative increase in number of villus epithelial cells not involved in absorp tion of amino acid; however, it is more likely to be due to a decrease in number of amino acid absorbing sites (carrier macromolecules) per villus epithelial cell.The need for amino acid is increased during infancy and childhood compared with the need later in life because infants require amino acids not only for normal body metabolism but also for growth. Per unit body weight, infants consume and also absorb larger amounts of amino acids from proteins than do adults. Greater amounts of amino acids can be absorbed in the intestine during infancy if the absorbing efficiency and/or the relative number of the absorbing sites in the intestine is greater in infants than in adults. Diffusion of amino acid across the intestinal mucosa may also b...

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supporting

confidence: 89%

Maturation of the Small Intestine: Absorption of L-Valine in Rats

Younoszai

Komnick

1982

Pediatr Res

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“…Steiner, Bourges, Farrish, Ross & Gray (1969) found Vmax for accumulation of valine by jejunal biopsies from obese humans of undefined metabolic status to be enhanced, while Bennetts & Ramaswamy (1980) found no difference between obese-diabetic (db/db) mice and controls in uptake of 1 mm leucine by brush-border membrane vesicles.…”

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confidence: 97%

TRANSPORT OF LEUCINE BY THE SMALL INTESTINE OF LEAN AND GENETICALLY OBESE (ob/ob) MICE

Morton

Hanson

1983

Exp Physiol

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SUMMARYTransport of leucine by the small intestine of obese (ob/ob) mice has been compared with that by intestine of lean controls at various stages in the development of the syndrome. At 10 weeks of age, when hyperphagia and hyperinsulinaemia are at their peak, transport (expressed per gram dry weight) ofa physiological concentration ofleucine (5 mM) by luminally perfused whole small intestine of obese mice was significantly lower both in vitro (-45 %) and in vivo (-27 %). Experiments involving fasting and long-term partial dietary restriction of obese mice suggested that the reduction in leucine transport was probably not a consequence of hyperphagia. The absence of any difference between lean and obese mice in the kinetics of unidirectional influx of leucine across the brush border contrasted with the findings from the luminal perfusion experiments. This discrepancy could indicate that the effect of the (ob/ob) genotype on leucine transport was at a stage in the process of transepithelial transport distal to the brush border, perhaps that of movement across the basolateral membrane.

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Absorptive Capacity of the Jejunum of Obese and Lean Subjects

Billich¹,

Bray²,

Gallagher³

et al. 1972

Arch Intern Med

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The jejunum of eight obese (mean weight 139 kg [306 lb 8 oz]) and four lean subjects (mean weight, 71 kg [156 lb 8 oz]) was perfused with isotonic glucose-sodium chloride solutions containing a nonabsorbable marker polyethylene glycol and, in four subjects, also folic acid, before and after a fi ve\x=req-\ day total caloric fast. Absorption of glucose, water, sodium, chloride, and folic acid and secretion of urea and potassium were determined. The absorptive capacity of the sub-stances measured was identical in normal\x=req-\

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Intestinal Uptake of Valine in Obesity

Cited by 6 publications

References 0 publications

Maturation of the Small Intestine: Absorption of L-Valine in Rats

Maturation of the Small Intestine: Absorption of L-Valine in Rats

TRANSPORT OF LEUCINE BY THE SMALL INTESTINE OF LEAN AND GENETICALLY OBESE (ob/ob) MICE

Absorptive Capacity of the Jejunum of Obese and Lean Subjects

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