Comparison of type I 5′-deiodination of thyroxine and of reverse-triiodothyronine in rat and chicken liver homogenates
1986; Elsevier BV; Volume: 63; Issue: 3 Linguagem: Inglês
10.1016/0016-6480(86)90139-5
ISSN1095-6840
Autores Tópico(s)Hormonal and reproductive studies
ResumoThe characteristics of 5′-deiodination in the chicken liver have been compared to those in the rat. Using 6-n-propyl-2-thiouracil (PTU) at 1 mM in vitro, it was shown that, in accordance with former in vivo studies, only type I 5′-deiodinase exists in the liver of the chicken. When PTU was used in a concentration (10 μM) close to its Ki species differences could be demonstrated as for PTU sensitivity. 5′-Deiodinase in the chicken liver was more susceptible against the inhibitor. The early thiol-independent phase of deiodination was longer in the chicken than in the rat. Reverse-triiodothyronine (r-T3) seemed to be a more suitable substrate for this enzyme in the chicken when compared to either T4 degradation or r-T3 degradation in the rat. It is concluded that major characteristics of 5′-deiodination in the chicken are similar to those in the rat; however, the slight variances observed might explain some species differences found earlier.
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