Dynamics of Amino Acid Transport in the Intact Intestine.

Jacobs, Francis A.; Lang, Arlene H.

doi:10.3181/00379727-118-29966

Cited by 13 publications

(6 citation statements)

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“…These high values are probably due to both the clearing of plasma from the foetal labyrinth and the accumulation of amino acids in this stationary plasma, during the 10-15 min required to cannulate the umbilical vessels. A greater efflux of amino acids has also been observed at the beginning of a perfusion of the intestinal lumen of the intact anaesthetized rat (Jacobs & Lang, 1965).…”

Section: Control Valuesmentioning

confidence: 80%

The transfer of free α‐amino nitrogen across the placental membrane in the guinea‐pig

Reynolds¹,

Young²

1971

The Journal of Physiology

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SUMMARY1. Transfer of endogenous a-amino nitrogen from the maternal to foetal side of the placental membrane was studied in the foetal guinea-pig placenta perfused, in situ via the umbilical vessels, with an artificial fluid. Changes in maternal placental blood flow were followed by measuring the transfer of antipyrine into the perfusate.2. Active transport by the membrane was demonstrated under these conditions by observing the increased ratio of L/D leucine appearing in the perfusate in comparison with the maternal plasma ratio.3. Reduction in maternal placental flow following haemorrhage was associated with a fall in transfer of amino nitrogen to about half of the control values.4. The concentration of ax-amino nitrogen in the perfusate was inversely proportional to the foetal placental flow which had a smaller influence on amino nitrogen transfer per min than did the maternal blood flow.5. Hypoxia and some inhibitors of oxidative metabolism were without influence on the transfer of a-amino nitrogen in this preparation.

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Section: Control Valuesmentioning

confidence: 80%

The transfer of free α‐amino nitrogen across the placental membrane in the guinea‐pig

Reynolds¹,

Young²

1971

The Journal of Physiology

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“…In situ procedures have been utilized in which absorption has been studied using ligated intestinal segments of the rat (Gibson and Wiseman, 1951) and sheep (Williams, 1969). Perfusion of the intestine of rats (Jacobs and Lang, 1965) or intestinal segments of sheep (Phillips et al, 1979) also has provided useful information. Tubes with double or triple lumens that are passed through the nasal cavity, down the esophagus, through the stomach and into the small intestine have been especially useful in measuring amino acid absorption in the intact intestine of the human (Cummins, 1952;FleshIer et al, 1966;.…”

Section: Amino Acid Absorptionmentioning

confidence: 99%

Intestinal absorption of protein hydrolysis products: a review.

Webb

1990

Journal of Animal Science

162

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Many experimental techniques have allowed researchers to probe the fate of hydrolysis products from proteins in the small intestine. An overview of amino acid and peptide absorption from the small intestine is presented with attention given to historical perspectives that have led to current concepts. Speculation about nutritional significance of these processes is offered. Species differences exist in site of amino acid absorption. Numerous mechanisms are available for the transport of amino acids, including Na(+)-dependent carriers (energy-requiring), Na(+)-independent carriers and diffusion. The relative contribution each transport system makes to absorption is dependent on substrate concentration. Individual amino acids are not absorbed with equal efficiency; methionine usually is absorbed in the greatest proportion. There are interactions among amino acids for transports by specific transport systems. Small peptides (mostly di- and tripeptides) are absorbed from the small intestine more rapidly than are free amino acids; peptides are transported by systems independent of those responsible for transporting free amino acids. Evidence exists that the active transport of these peptides is via a proton gradient. Although the concept that peptides are absorbed intact into the circulation is not universally accepted, evidence supporting the possibility of tissue utilization of these small peptides is accumulating.

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“…However, the validity of amino acid analysis for determining the nutritive value of a protein is dependent on good availability or digestibility of the amino acids (Rama Rao et aI., 1964; olsen et al' 1968). Even though the results of experiments carried out in our laboratory (Flipot et al,197r) "iJ"g lfr"r" lines, and, in thaicase, an erroneous picture of the amino acids actually digested by the chickens would be obtained' (Jacobs and Lang, 1965;Squibb, 1968).…”

Section: Introductionmentioning

confidence: 99%