Nature and Appearance of Protein Digestion Products in Upper Mesenteric Blood

Levenson, Stanley Μ.; Rosen, Harvey M.; Upjohn, Harold L.

doi:10.3181/00379727-101-24873

Cited by 16 publications

(5 citation statements)

References 1 publication

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“…Little or no detection of absorbed intact peptides was reported in dogs (Levenson et al, 1959) and rats (Wiggans and Johnston, 1959). Others have reported that up to 85% of AA entering the portal blood was in the form of small peptides in rats (Gardner, 1975), Holstein calves (Koeln et al, 1993), lactating Holstein cows (Tagari et al, 2004(Tagari et al, , 2008, Friesian steers (Seal and Parker, 1996), sheep (Remond et al, 2000), and yak cows (Han et al, 2001a,b).…”

Section: Peptides and Portal-drained Viscera Aa Fluxmentioning

confidence: 99%

BOARD-INVITED REVIEW: Peptide absorption and utilization: Implications for animal nutrition and health

Gilbert

Wong

Webb

2008

Journal of Animal Science

294

209

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Over the last 50 yr, the study of intestinal peptide transport has rapidly evolved into a field with exciting nutritional and biomedical applications. In this review, we describe from a historical and current perspective intestinal peptide transport, the importance of peptides to whole-body nutrition, and the cloning and characterization of the intestinal peptide transporter, PepT1. We focus on the nutritional significance of peptide transport and relate these findings to livestock and poultry. Amino acids are transported into the enterocyte as free AA by a variety of AA transporters that vary in substrate specificity or as di- and tripeptides by the peptide transporter, PepT1. Expression of PepT1 is largely restricted to the small intestine in most species; however, in ruminants, peptide transport and activity is observed in the rumen and omasum. The extent to which peptides are absorbed and utilized is still unclear. In ruminants, peptides make a contribution to the portal-drained visceral flux of total AA and are detected in circulating plasma. Peptides can be utilized by the mammary gland for milk protein synthesis and by a variety of other tissues. We discuss the factors known to regulate expression of PepT1 including development, diet, hormones, diurnal rhythm, and disease. Expression of PepT1 is detected during embryological stages in both birds and mammals and increases with age, a strategic event that allows for the immediate uptake of nutrients after hatch or birth. Both increasing levels of protein in the diet and dietary protein deficiencies are found to upregulate the peptide transporter. We also include in this review a discussion of the use of dietary peptides and potential alternate routes of nutrient delivery to the cell. Our goal is to impart to the reader the nutritional implications of peptide transport and dietary peptides and share discoveries that shed light on various biological processes, including rapid establishment of intestinal function in early neonates and maintenance of intestinal function during fasting, starvation, and disease states.

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Section: Peptides and Portal-drained Viscera Aa Fluxmentioning

confidence: 99%

BOARD-INVITED REVIEW: Peptide absorption and utilization: Implications for animal nutrition and health

Gilbert

Wong

Webb

2008

Journal of Animal Science

294

209

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“…It is generally accepted that during digestion proteins are broken down to their constituent amino acids before being absorbed into the portal bloodstream (Denton, Gershoff & Elvehjem, 1953;Hartmann, Lenz, Lopez-Calleja & Miinzenberg, 1956;Levenson, Rosen & Upjohn, 1959;Dawson & Holdsworth, 1962). The terminal stage of this process, hydrolysis of diand tri-peptides, is, however, not completely understood.…”

mentioning

confidence: 99%

The sites of hydrolysis of dipeptides containing leucine and glycine by rat jejunum in vitro

Fern

Hider

London

1969

Biochemical Journal

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1. The effect of peptides containing leucine and glycine on accumulation of leucine and glycine by everted jejunal rings was studied. 2. It was shown that, on a molar basis, leucyl-leucine is a more effective inhibitor of uptake of [(14)C]leucine than is either leucylglycine or glycyl-leucine. These latter dipeptides behave alike. 3. The concentration of the dipeptides and their constituent amino acids in both the incubation medium and the tissue has been followed in these experiments by amino acid analysis. No leucine-containing peptides were observed in the tissue. 4. The inhibitory effects of the mixed dipeptides are altered by pH changes in an analogous way to the alterations in peptidase activity. 5. The experimental results indicate that leucine-containing peptides are hydrolysed before the transport step. 6. Glycylglycine, on the other hand, has only a small effect on the accumulation of glycine, although large amounts of the peptide accumulate unchanged in the tissue. This suggests that glycylglycine is taken up by a different mechanism to that for the leucine dipeptides.

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“…Analysis of the portal blood has given no evidence of the presence of peptides, even when these had been shown to be present in the intestinal contents (Levenson, Rosen & Upjohn, 1959;Dent & Schilling, 1949;Parshin & Rubel, 1951;Dawson & Holdsworth, 1962;Dawson & Porter, 1962). The finding that amino acids could be absorbed more readily by the intestine from peptides than from free amino acids, not only from di-, tri-, and tetra-glycine (Craft Craft, Geddes, Hyde, Wise & Matthews, 1968), which may not relate to protein digestion (Rhodes, Eichholz & Crane, 1967), but also from mixed peptides Craft, Crampton, Lis & Matthews, 1969;Matthews, Lis, Cheng & Crampton, 1969), indicated that small peptides may be an important component of the nitrogen absorbed from the gut.…”

Section: Vol 30mentioning

confidence: 99%

“…Peraino & Harper, 1963 ;Wheeler & Morgan, 1958;Denton, Gershoff & Elvehjem, 1953;Porter & Williams, 1963). The rise may occur within 0.5 h of eating and may last for 6-8 h in the rat, dog and man (Frame, 1958;Levenson et al 1959;Crane & Neuberger, 1960;Dawson & Porter, 1962).…”

Section: Plasma Amino Acid Levelsmentioning

confidence: 99%