Femoral growth plate is sensitive to loss of cardiac shunt in the American alligator
Femoral growth plate is sensitive to loss of cardiac shunt in the American alligator
复制标题
股骨生长板对美洲短吻鳄心脏分流的丧失很敏感
DOI：
10.1096/fasebj.26.1_supplement.908.3
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
J. Hicks
中科院分区：
文献类型：
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作者：
T. Owerkowicz;Johnny Yang;J. Blank;J. Eme;J. Hicks
纵向生长速率（LGR）与鸟类生长板的钙化软骨柱高度（CCC）相关。为了推断非鸟类恐龙的肢骨生长模式，需要在鳄鱼类动物中记录这种相关性。我们测试了在实验室条件下饲养两年的幼年短吻鳄的股骨中LGR - CCC的相关性，并注射了荧光染料（茜素、钙黄素）。一些短吻鳄通过左主动脉消融被限制为串联循环（n=24），而假手术对照组保持平行循环（n=36）。动物要么保持久坐不动，要么进行严格的步行或游泳运动（n=20）。我们发现，与平行循环的短吻鳄相比，串联循环的短吻鳄的CCC与LGR相关，显著增加（+36%）。力竭运动使生长板远端厚度减少（- 15%），而近端没有，提示局部生物力学载荷作用。我们认为肺旁路分流术的缺失会导致更高的全身动脉氧张力，从而允许更大的氧气通过生长板的扩散距离。在祖龙祖先中，较厚的生长板可能与串联循环的起源同时出现，从而为后来获得快速生长和吸热代谢奠定了基础。NSF IOB 04445680 - JWH资助。
Longitudinal growth rate (LGR) has been shown to correlate with calcified cartilage column height (CCC) in the growth plates of birds. In order to infer limb bone growth patterns in non‐avian dinosaurs, this correlation needs to be documented in crocodilians. We tested the LGR‐CCC correlation in femora of juvenile alligators raised for two years under laboratory conditions, and injected with fluorochrome dyes (alizarin, calcein). Some alligators were constrained to in‐series circulation by left aortic ablation (n=24), whereas sham‐operated controls retained in‐parallel circulation (n=36). Animals either remained sedentary or were subjected to rigorous walking or swimming exercise (n=20). We found CCC correlated with LGR and was significantly augmented (+36%) in alligators with in‐series circulation compared to those with in‐parallel circulation. Exhaustive exercise reduced thickness (−15%) of the distal, but not proximal, growth plate, suggesting local effect of biomechanic loading. We propose loss of the pulmonary bypass shunt results in higher systemic arterial oxygen tension, which allows for greater oxygen diffusion distance through the growth plate. Among archosaur ancestors, thicker growth plates may have appeared concurrently with the origin of in‐series circulation, and thus set the stage for later acquisition of fast growth and endothermic metabolism. Supported by NSF IOB 04445680 to JWH.