Amino Acids in Gut Contents and Blood Plasma of Rats as Affected by Dietary Amino Acid Imbalance

• Published in: The Journal of nutrition Vol. 105; no. 1; pp. 69 - 79
• Main Authors: Nasset, E.S., Ju, J.S.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.01.1975
• Subjects: amino acid homeostasis; amino acids in gut contents; plasma amino acids; protein digestion; protein digestion; plasma amino acids; amino acid homeostasis; amino acids in gut contents
• ISSN: 0022-3166
• DOI: 10.1093/jn/105.1.69

The objective of this investigation was to determine how much and how soon amino acid imbalance interferes with amino acid homeostasis in blood plasma and in the digestive tract. Amino acid imbalance was induced in rats by feeding them a diet containing 5% casein to which a supplement of indispensable amino acids devoid of histidine was added. Blood and gut contents were obtained from nonfasted rats after 1 to 6 days of feeding. Amino acid analyses revealed that ingestion of the imbalanced diet resulted in unusual amino acid patterns in blood, which in several instances changed in apparently unrelated ways. The molar ratio of threonine in plasma, for example, continued to rise and on day 6 of the experiment, it was 320% of the value obtained with stock diet, without a quantitatively corresponding value in gut contents. The molar ratios of leucine in both blood and gut contents were depressed. The imbalanced diet contained enough readily absorbable free amino acids to cause an early influx into the bloodstream that could precede the influx of protein-bound amino acids arising from hydrolysis of dietary casein and luminal endogenous proteins.