Das D K, Bandyopadhyay D, Bandyopadhyay S, Neogi A
Acta Endocrinol (Copenh). 1984 Aug;106(4):569-76. doi: 10.1530/acta.0.1060569.
The effect of thyroid hormone on the beta-adrenergic receptor in foetal cardiac membranes was analysed by measuring the binding of (-)[3H]DHA. The specific activities (per mg protein) of beta-adrenergic receptors decreased with advancing gestational age, whereas the total activities (per heart) increased under the similar conditions. The change in the binding affinities was not statistically significant. 1; 3,5,3'-L-triiodothyronine (T3) stimulated the (-)[3H]DHA binding capacities of the cardiac membranes of foetuses of all age groups. The enhancement in the receptor activity was completely inhibited actinomycin D or cycloheximide. The contents of epinephrine, norepinephrine and cAMP increased with advancing gestational age; but T3 had no significant effect on the catecholamines or cAMP. Similarly, the activities of the basal, NaF stimulated and Gpp(NH)p stimulated adenylate cyclase remained unaltered by T3, but the activities increased progressively with foetal maturity. The absolute values of catecholamine stimulated adenylate cyclase activities in the hearts of T3 treated foetuses were, however, higher compared to those in the untreated foetuses. The enhancement of the activities were totally blocked by the action of actinomycin D, cycloheximide or propranolol. Our results indicate that thyroid hormone enhances the number of beta-adrenergic receptor binding sites by synthesizing new receptor proteins resulting in increased catecholamine sensitivity.
通过测量（-）[³H]DHA的结合来分析甲状腺激素对胎儿心脏膜中β-肾上腺素能受体的影响。β-肾上腺素能受体的比活性（每毫克蛋白质）随着胎龄的增加而降低，而在相似条件下总活性（每颗心脏）增加。结合亲和力的变化无统计学意义。1,3,5,3'-L-三碘甲状腺原氨酸（T3）刺激了所有年龄组胎儿心脏膜的（-）[³H]DHA结合能力。受体活性的增强被放线菌素D或环己酰亚胺完全抑制。肾上腺素、去甲肾上腺素和cAMP的含量随着胎龄的增加而增加；但T3对儿茶酚胺或cAMP无显著影响。同样，基础的、氟化钠刺激的和Gpp（NH）p刺激的腺苷酸环化酶活性不受T3影响，但随着胎儿成熟度增加而逐渐升高。然而，T3处理的胎儿心脏中儿茶酚胺刺激的腺苷酸环化酶活性的绝对值高于未处理的胎儿。这些活性的增强被放线菌素D、环己酰亚胺或普萘洛尔的作用完全阻断。我们的结果表明，甲状腺激素通过合成新的受体蛋白来增加β-肾上腺素能受体结合位点的数量，从而导致儿茶酚胺敏感性增加。
