title: Arginine affects urea synthesis in rats treated with thyroid hormone.
abstract: The purpose of the present study was to determine whether the regulation of urea synthesis was mediated through the activation of N-acetylglutamate synthesis by arginine and whether the concentration of glutamate or activity of N-acetylglutamate synthetase might control N-acetylglutamate concentration when the thyroid status was manipulated. Three groups of rats were given 6-propyl-2-thiouracil (PTU, thyroid inhibitor) without triiodothyronine (T3) treatment, treated with PTU + T3 or treated with neither PTU nor T3 (control). Urinary excretion of urea, liver concentration of N-acetylglutamate and plasma concentration of arginine in rats given PTU + T3 were significantly lower than in rats given PTU alone. Liver concentration of N-acetyl-glutamate was correlated with plasma concentration of arginine (r = 0.842, P < 0.001). The activity of N-acetylglutamate synthetase and glutamate concentration in liver of the PTU + T3-treated group were significantly higher than in the group treated with PTU alone. Arginine administration (0.5 mmol/100 g body wt) elevated the liver concentration of N-acetylglutamate in all three groups. The results suggest that the greater concentration of arginine in the hypothyroid (PTU alone) rats is likely to increase the N-acetylglutamate concentration and stimulate urea synthesis.
authors.affiliation: Department of Home Economics, Aichi University of Education, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hayase
authors.forename: G
authors.initials: G
authors.lastname: Yonekawa
authors.forename: A
authors.initials: A
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D001120:Arginine / Q000097:blood / Q000494:pharmacology*; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D011441:Propylthiouracil / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014284:Triiodothyronine / Q000494:pharmacology*; D014508:Urea / Q000378:metabolism* / Q000652:urine
chemical_list: D005971:Glutamates; D014284:Triiodothyronine; D018698:Glutamic Acid; D011441:Propylthiouracil; D014508:Urea; D001120:Arginine; C016195:N-acetylglutamic acid