Transport and Incorporation of Amino Acids into the Aortic Wall: Influence of Age and Hormones

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Abstract
The accumulation of [alpha]-aminoisobutyric acid-1-C14 (AIB) in rat aortic tissue is not influenced by age. While it is increased in vitro in the presence of insulin, no significant decrease could be observed in mild diabetes. Thyrotoxicosis increases and athyreosis decreases this accumulation. Addition of glucose to the medium does not influence the accumulation of AIB. The incorporation of radioactive glycine, alanine and leucine into aortic tissue proteins of old rats is less than in young animals. It is greatly increased by insulin without glucose inthe medium and decreased in mild alloxan diabetes. Thyrotoxicosis causes an accelerated incorporation, while in athyreosis it is less than normal. Addition of glucose to the medium causes an increased incorporation of these amino acids. Leucine, alanine and glycine partially inhibit the accumulation of AIB and cancel to some extent the effect of insulin and thyrotoxicosis on this process. The extent to which the influence on transport participates in the described effects on the incorporation of natural amino acids into aortic wall proteins is discussed.