Cabrera Fischer E I, Bia D, Camus J M, Zócalo Y, de Forteza E, Armentano R L
Facultad de Ingeniería, Ciencias Exactas y Naturales, Favaloro University, Solís 453, Buenos Aires, Argentina.
Acta Physiol (Oxf). 2006 Oct;188(2):103-11. doi: 10.1111/j.1748-1716.2006.01614.x.
An adventitia dependent regulation of the vascular smooth muscle tone has been described. However, if the adventitia plays an active role on arterial wall biomechanical behaviour and functions remains to be established. Our aim was to characterize the influence of adventitia on arterial wall mechanical properties and the arterial conduit and buffer functions.
Ovine brachiocephalic arteries were studied in vivo (n = 8) and in vitro (with null tone) in a circulation mock (n = 8). Isobaric, isoflow and isofrequency studies were performed. In each segment, pressure and diameter waves were assessed before and after adventitia removal. From the arterial stress-strain relationship, we derived the elastic and the viscous modulus. The buffering and conduit functions were calculated using the Kelvin-Voigt's time constant and the inverse of the characteristic impedance, respectively.
In in vivo studies arterial diameter decreased after adventitia removal (P < 0.05). Elastic and viscous modulus in in vivo studies were significantly higher in adventitia-removed arteries, compared with values in intact vessels (P < 0.05). This behaviour was not observed in in vitro experiments. An impairment of buffer and conduit functions was observed in vivo after adventitia removal (P < 0.05), while both functions remain unchanged in in vitro studies (P > 0.05).
Arterial wall viscosity and elasticity were influenced by adventitia removal in in vivo studies, possibly by a smooth muscle-dependent mechanism, since it was not present in in vitro experiments. Adventitia would be involved in a physiological mechanism of arterial wall viscous and elastic properties regulation, that could influence arterial buffering and conduit functions.
已有文献报道血管平滑肌张力存在外膜依赖性调节。然而，外膜是否在动脉壁生物力学行为和功能中发挥积极作用仍有待确定。我们的目的是描述外膜对动脉壁力学性能以及动脉管道和缓冲功能的影响。
对绵羊头臂动脉进行体内研究（n = 8）和体外模拟循环研究（无张力，n = 8）。进行了等压、等流量和等频率研究。在每个节段，在去除外膜前后评估压力和直径波。从动脉应力-应变关系中，我们得出弹性模量和粘性模量。分别使用开尔文-维格纳时间常数和特性阻抗的倒数来计算缓冲功能和管道功能。
在体内研究中，去除外膜后动脉直径减小（P < 0.05）。与完整血管相比，体内研究中去除外膜的动脉的弹性模量和粘性模量显著更高（P < 0.05）。在体外实验中未观察到这种现象。在体内去除外膜后观察到缓冲功能和管道功能受损（P < 0.05），而在体外研究中这两种功能均保持不变（P > 0.05）。
在体内研究中，去除外膜会影响动脉壁的粘性和弹性，可能是通过一种平滑肌依赖性机制，因为在体外实验中不存在这种机制。外膜可能参与了动脉壁粘性和弹性特性调节的生理机制，这可能会影响动脉的缓冲和管道功能。
