Non-Protein Nitrogen Changes in Serum and Plasma of Rats Following Thermal Injury.

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Abstract
Summary 1. Ultrafiltrates of plasma and serum from normal and thermally injured rats were utilized in a study of non-protein nitrogen changes following thermal injury. The rats were burned deeply over about 30% of the body surface and the bloods were collected 11-12 hours after injury. 2. Absorption spectra were obtained before and after in vitro ultraviolet irradiation of the sera ultrafiltrates. The changes observed in the spectrum of the sera ultrafiltrate of the injured rats is consistent with a modification qualitative and/or quantitative in the sera amino acids, free and combined, and with the appearance of purine containing compounds. 3. Almost the entire increase in filterable nitrogen in the sera of rats after thermal injury consists of urea and free and combined amino nitrogen in their normal relationships. 4. Measurements of specific amino compounds were carried out by ion exchange chromatographic and colorimetric ninhydrin technics. The results obtained by these methods for the amino acids of plasma ultrafiltrates of normal rats are similar to values obtained by others for rat plasma amino acids using microbiologic technics. 5. In the plasma ultrafiltrate of injured rats, there are increases of some amino acids, particularly tyrosine, phenylalanine, and histidine, while other amino acids are decreased. Quantitatively, the largest part of the increase in amino nitrogen is made up of a forepeak (taurine?) and an amino acid conjugate. 6. The amino acid conjugate includes a large fraction unaffected by hydrolysis and a few of the common amino acids. The composition of the conjugate is similar in normal and injured rats.