Torres A, Tucker D C
Psychology Department, University of Alabama, Birmingham 35294.
Am J Physiol. 1993 Jan;264(1 Pt 2):H244-51. doi: 10.1152/ajpheart.1993.264.1.H244.
Embryonic rat myocardium was grafted into the anterior eye chamber (in oculo) of adult host rats in a series of two experiments that studied the effects of thyroid hormones [triiodothyronine (T3) and thyroxine (T4)] on heart tissue developing without hemodynamic load. In each experiment, surgical sympathectomy of one eye chamber was used to define possible interactions between thyroid hormones and sympathetic innervation to the graft. In the first experiment, propylthiouracil (PTU, 20 mg/kg sc) greatly suppressed growth and beating rate of whole heart grafts, while excess T4 (0.1 mg/kg sc) transiently increased beating rate but not growth. In the second experiment, T3 (5 mg/21 days, slow-release pellet) failed to promote growth in ventricular grafts. However, the size of atrial grafts in surgically sympathectomized eye chambers was larger in T3-treated compared with control rats. T3 administration increased beating rate in ventricular grafts. In both experiments, thyroid hormone treatments were effective in increasing heart weight-to-body weight ratios in the host rats. The data suggest that exposure to normal levels of thyroid hormones may be necessary for optimal cardiac growth. The data also support the hypothesis that a hemodynamic load is required for thyroid hormone-induced cardiac growth.
在一系列两项实验中，将胚胎大鼠心肌移植到成年宿主大鼠的前房（眼内），研究甲状腺激素[三碘甲状腺原氨酸（T3）和甲状腺素（T4）]对在无血流动力学负荷情况下发育的心脏组织的影响。在每项实验中，对一个眼房进行手术交感神经切除术，以确定甲状腺激素与移植心脏的交感神经支配之间可能存在的相互作用。在第一个实验中，丙基硫氧嘧啶（PTU，20mg/kg皮下注射）极大地抑制了整个心脏移植物的生长和跳动率，而过量的T4（0.1mg/kg皮下注射）短暂地增加了跳动率，但没有促进生长。在第二个实验中，T3（5mg/21天，缓释微丸）未能促进心室移植物的生长。然而，与对照大鼠相比，接受T3治疗的手术去交感神经眼房中的心房移植物尺寸更大。给予T3可增加心室移植物的跳动率。在两项实验中，甲状腺激素治疗均有效地增加了宿主大鼠的心脏重量与体重比。数据表明，暴露于正常水平的甲状腺激素可能是心脏最佳生长所必需的。数据还支持以下假设，即甲状腺激素诱导的心脏生长需要血流动力学负荷。
