title: Role of ornithine in urea synthesis in rats treated with thyroid hormone.
abstract: The purpose of this study was to find whether the regulation of urea synthesis was mediated through the activation of N-acetyglutamate synthesis by ornithine when the thyroid status was manipulated. Experiments were done on three groups of rats, given 6-propyl-2-thiouracil (PTU, a thyroid inhibitor) without triiodothyronine (T3) treatment, treated with PTU + T3, or neither PTU nor T3 (control). Urinary excretion of urea and the liver concentrations of ornithine and N-acetylglutamate in rats given PTU + T3 were significantly lower than in rats given PTU alone. The liver concentration of N-acetylglutamate was correlated with the liver concentration of ornithine (r = 0.920, p < 0.001). Ornithine 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 ornithine in the hypothyroid (PTU alone) rats is likely to increase the N-acetylglutamate concentration in liver 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: A
authors.initials: A
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D005971:Glutamates / Q000032:analysis / Q000378:metabolism; D008099:Liver / Q000737:chemistry; D008297:Male; D009952:Ornithine / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology*; D011441:Propylthiouracil / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014284:Triiodothyronine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014508:Urea / Q000097:blood / Q000378:metabolism* / Q000652:urine
chemical_list: D005971:Glutamates; D014284:Triiodothyronine; D011441:Propylthiouracil; D014508:Urea; D009952:Ornithine; C016195:N-acetylglutamic acid