Hemodynamic consequences of eliminating right‐to‐left cardiac shunt in the American alligator
Hemodynamic consequences of eliminating right‐to‐left cardiac shunt in the American alligator
复制标题
消除美洲短吻鳄右向左心脏分流的血流动力学后果
DOI：
10.1096/fasebj.21.6.a1399-b
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
J. Hicks
中科院分区：
文献类型：
--
作者：
J. Blank;Tomasz Owerkovics;June Gwalthney;J. Eme;B. Rourke;J. Hicks
心脏分流在所有非鸟类爬行动物中都有发生，人们提出了许多假说来解释它的进化原因。然而，到目前为止，还没有实验研究能够去除分流的能力。鳄鱼心脏的形态，有一个完全分裂的心室，允许通过手术闭塞左主动脉弓（LAo）在其底部，近Panizza孔，消除从右到左（R - L）分流。我们消除了幼年美洲短吻鳄（短吻鳄）急性和慢性的R - L分流。在麻醉和人工通气的短吻鳄中，我们测量了肺动脉（PA）、左主动脉（LAo）和右心室（RV）闭塞前后的血流量和血压。麻醉动物的左脑有大量血流。用氢电极确认R - L分流。左心室的急性闭塞消除了左心室的血流，阻止了左心室的R - L分流，并导致右心室压力和功的大幅增加。这些影响可以通过去除LAo底部的缝线来逆转。术后8-12个月慢性LAo闭塞动物也表现出类似的LAo血流缺失、分流缺乏和右心室压力升高。对这些慢性LAo闭塞动物心室的初步分析表明，心肌蛋白组成的改变可能是由慢性过载引起的。
Cardiac shunting occurs in all non‐avian reptiles and many hypotheses have been proposed to explain why it has evolved. However, no study to date has experimentally removed the ability to shunt. The morphology of the crocodilian heart, which has a completely divided ventricle, allows elimination of right‐to‐left (R‐L) shunting by surgical occlusion of the left aortic arch (LAo) at its base, proximal to the foramen of Panizza. We eliminated R‐L shunt in juvenile American alligators (Alligator mississippiensis) both acutely and chronically. In anaesthetized and artificially ventilated alligators, we measured blood flow and pressure in the pulmonary artery (PA), left aorta (LAo) and right ventricle (RV) before and after LAo occlusion. Anesthetized animals exhibited a substantial flow in the LAo. R‐L shunt was confirmed with a hydrogen electrode. Acute occlusion of the LAo eliminated flow in the LAo, prevented R‐L shunt, and produced a substantial rise in RV pressure and work. These effects could be reversed by removing the suture at the base of the LAo. Chronically LAo‐occluded animals tested 8–12 months after surgery exhibited a similar absence of LAo‐flow, lack of shunt, and increased RV pressure. Preliminary analysis of ventricles from these chronically LAo‐occluded animals suggests alterations in myocardial protein composition which may result from chronic overload.