[Comparison of 2 technics (ninhydrin vs. TNSB) for estimating circulating amino acid nitrogen, applied to the study of the intestinal absorption of solutions of free amino acids or small peptides].
The intestinal absorption of nitrogen from amino acids present in a solution of small peptides or of free amino acids with the same pattern, perfused intraduodenally, has been studied using two analytical techniques [2, 4, 6 trinitrobenzene-1-sulfonic acid (TNBS) after dialysis of the blood vs ninhydrine after chromatography] to determine post-perfusion porto arterial differences and to measure blood flow rate in the portal vein. The results obtained on blood nitrogen level with the chromatographic method were always higher than those obtained using the TNBS method. The differences in the values varied from 8 to 24% according to post-perfusion time and to blood sample origin (arterial or portal). On the contrary, the absorbed amounts of nitrogen measured by either analytical technique were not very much different: no significant and systematic deviation was found between the two. The TNBS method is thus useful as a preliminary approach to very elaborate studies on intestinal absorption. In these conditions, the nitrogen of amino acids from duodenally-perfused small peptides was absorbed earlier and more rapidly than that from a perfusion of a solution of free amino acids. The amount of nitrogen appearing in the portal vein five hours after perfusion exceeded the perfused amount owing to considerable recycling of endogenous nitrogen.
Laboratoire de Physiologie de la Nutrition, C.R.J., I.N.R.A., Jouy-en-Josas, France.
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Simoes Nunes
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Roger
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D007408:Intestinal Absorption; D008297:Male; D009555:Ninhydrin; D009584:Nitrogen / Q000097:blood*; D010455:Peptides / Q000378:metabolism*; D013552:Swine / Q000097:blood / Q000378:metabolism*; D013997:Time Factors; D014302:Trinitrobenzenesulfonic Acid
D000596:Amino Acids; D010455:Peptides; D014302:Trinitrobenzenesulfonic Acid; D009555:Ninhydrin; D009584:Nitrogen
Comparaison de deux techniques d'estimation (ninhydrine vs TNBS) de l'azote des acides aminés circulants, appliquées à l'étude de l'absorption intestinale de solutions d'acides aminés libres ou de petits peptides.