Hepatic amino nitrogen conversion and organ N-contents in hypothyroidism, with thyroxine replacement, and in hypethyroid rats

• Published in: Journal of hepatology 1997-02, Vol.26 (2), p.409-416
• Main Authors: Grøfte, Thorbjørn, Wolthers, Troels, Jensen, Dorthe Svenstrup, Møller, Niels, Jørgensen, J.O.L., Ørskov, Hans, Vilstrup, Hendrik
• Format: Article
• Language: English
• Subjects: Hepatic amino nitrogen conversion; hyperthyroidism; Hypothyroidism; Organ N-contents; Thyroxine replacement
• ISSN: 0168-8278; 1600-0641
• DOI: 10.1016/S0168-8278(97)80059-1

Background/Aims: The role of thyroid hormones in the regulation of hepatic conversion of amino nitrogen to urea is unresolved. The present study was designed to assess ureagenesis in rats with experimentally well-established hypo- and hyperthyroidism. The possible role of propylthiuracil (PTU), used for induction of hypothyroidism, was ascertained during thyroxine replacement of PTU treated hypothyroid rats. Methods: Basal blood amino nitrogen concentrations (AAN), the urea nitrogen synthesis rate (UNSR) and the maximal hepatic capacity for urea nitrogen synthesis (CUNS) obtained during alanine infusion were determined together with N-contents in the soleus muscle and kidneys in experimentally hypothyroid rats( n=19), upon thyroxine replacement ( n=14) and in experimentally hyperthyroid rats ( n=19). Hypothyroidism was induced by adding propylthiouracil (0.05%) to the drinking water for 5 weeks. Hyperthyroidism was induced by thyroxine 100 μg/100 g body weight. Results: During hyperthyroidism, T 3 fell to less than 10%, food intake was halved, and body weight fell by 13%. Basal blood AAN fell by 25% ( p