Drexler E S, Bischoff J E, Slifka A J, McCowan C N, Quinn T P, Shandas R, Ivy D D, Stenmark K R
National Institute of Standards and Technology, Boulder, CO 80305.
Zimmer, Inc., Warsaw, IN 46581-0708.
J Res Natl Inst Stand Technol. 2008 Aug 1;113(4):239-49. doi: 10.6028/jres.113.018. Print 2008 Jul-Aug.
Changes in the compliance properties of large blood vessels are critical determinants of ventricular afterload and ultimately dysfunction. Little is known of the mechanical properties of large vessels exhibiting pulmonary hypertension, particularly the trunk and right main artery. We initiated a study to investigate the influence of chronic hypoxic pulmonary hypertension on the mechanical properties of the extrapulmonary arteries of rats. One group of animals was housed at the equivalent of 5000 m elevation for three weeks and the other held at ambient conditions of ~1600 m. The two groups were matched in age and gender. The animals exposed to hypobaric hypoxia exhibited signs of pulmonary hypertension, as evidenced by an increase in the RV/(LV+S) heart weight ratio. The extrapulmonary arteries of the hypoxic animals were also thicker than those of the control population. Histological examination revealed increased thickness of the media and additional deposits of collagen in the adventitia. The mechanical properties of the trunk, and the right and left main pulmonary arteries were assessed; at a representative pressure (7 kPa), the two populations exhibited different quantities of stretch for each section. At higher pressures we noted less deformation among the arteries from hypoxic animals as compared with controls. A four-parameter constitutive model was employed to fit and analyze the data. We conclude that chronic hypoxic pulmonary hypertension is associated with a stiffening of all the extrapulmonary arteries.
大血管顺应性特性的改变是心室后负荷的关键决定因素，最终会导致功能障碍。对于表现出肺动脉高压的大血管的力学特性，尤其是肺动脉干和右主肺动脉，人们了解甚少。我们开展了一项研究，以调查慢性低氧性肺动脉高压对大鼠肺外动脉力学特性的影响。一组动物饲养在相当于海拔5000米的环境中三周，另一组饲养在海拔约1600米的环境条件下。两组在年龄和性别上相匹配。暴露于低压低氧环境的动物表现出肺动脉高压的迹象，右心室/（左心室+室间隔）心脏重量比增加证明了这一点。低氧动物的肺外动脉也比对照组的厚。组织学检查显示中膜厚度增加，外膜有额外的胶原沉积。评估了肺动脉干以及左右主肺动脉的力学特性；在代表性压力（7 kPa）下，两组各节段的伸展量不同。在更高压力下，我们注意到与对照组相比，低氧动物的动脉变形较小。采用四参数本构模型对数据进行拟合和分析。我们得出结论，慢性低氧性肺动脉高压与所有肺外动脉的硬化有关。
