Rongish B J, Torry R J, Tomanek R J
Department of Anatomy, University of Iowa, Iowa City 52242.
Am J Physiol. 1995 Feb;268(2 Pt 2):H811-6. doi: 10.1152/ajpheart.1995.268.2.H811.
We tested the hypothesis that neovascularization of embryonic hearts is independent of thyroid hormones. To dissociate the effects of hemodynamic load from the direct influence of thyroid hormones on coronary neovascularization, we grafted avascular, gestational day 12 rat hearts to the anterior eye chamber of adult rats receiving daily injections of thyroxine (T4; 0.25 mg/kg sc), propylthiouracil (PTU; 10 mg/kg ip), or saline (control). After 21 days, grafts were perfuse fixed and prepared for transmission electron microscopy. Neither T4 nor PTU treatment affected size or mass of the unloaded graft, or the volume densities of vessels, myocytes, or the extracellular matrix, which were determined by standard point-counting techniques. Thus neither exogenous administration of T4 nor the induction of hypothyroidism in host rats produced a significant effect on the growth or vascularity of the unloaded hearts. We conclude that vascular growth in embryonic rat hearts cultured in oculo is independent of thyroid hormones and that the angiogenic effect of thyroid hormones in loaded hearts is a consequence of increased work-related events.
我们检验了胚胎心脏血管新生独立于甲状腺激素这一假说。为了将血流动力学负荷的影响与甲状腺激素对冠状动脉血管新生的直接影响区分开来，我们将无血管的妊娠第12天大鼠心脏移植到每日接受甲状腺素（T4；0.25mg/kg皮下注射）、丙硫氧嘧啶（PTU；10mg/kg腹腔注射）或生理盐水（对照）注射的成年大鼠的前房。21天后，移植物进行灌注固定并制备用于透射电子显微镜检查。T4和PTU处理均未影响未负荷移植物的大小或质量，也未影响通过标准点计数技术测定的血管、心肌细胞或细胞外基质的体积密度。因此，无论是外源性给予T4还是诱导宿主大鼠甲状腺功能减退，对未负荷心脏的生长或血管形成均未产生显著影响。我们得出结论，在眼内培养的胚胎大鼠心脏中的血管生长独立于甲状腺激素，并且甲状腺激素在负荷心脏中的血管生成作用是与工作相关事件增加的结果。
