MECHANICAL EQUILIBRIUM OF BLOOD VESSEL WALLS
MECHANICAL EQUILIBRIUM OF BLOOD VESSEL WALLS
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DOI：
10.1152/ajplegacy.1971.221.5.1310
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发表时间：
1971-01-01
影响因子：
--
通讯作者：
OKA, S
中科院分区：
文献类型：
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作者：
AZUMA, T;OKA, S
AEUMA、TAKEHIKO和SYOTEN OKA。血管壁的机械平衡。am. J. Physiol.221（5）：1310 - 1318. 1971.-本文根据我们提出的适用于任何空心圆柱管在恒定内外压下的力学平衡的新的一般方程，检验了应用拉普拉斯定律于血管力学平衡的有效性。理论分析和实验结果表明，微小血管壁的周向张力必须为负。这种负张力的出现表明壁处于压缩状态而不是拉伸状态。由于在正跨壁压下的负张力不能由拉普拉斯定律来假定，因此该定律不应应用于这些血管，即使作为一般方程的近似。并利用该方程讨论了容器力学平衡的稳定性。微动脉或毛细血管前括约肌的管腔是否闭合，仅取决于产生的主动张力是否超过临界值，而不取决于血管内压力是否小于临界值，即临界闭合压力。因此，微循环的物理稳定性被证明仅由血管紧张度而不是由跨壁压决定。圆管通用方程;拉普拉斯定律;周向张力;负张力;临界闭合压力;主动张力;弹性张力;跨壁压;血管外压;血管内压;弹性图;均衡曲线自1951年以来，伯顿和他的同事们（4、5、8、10、14）将拉普拉斯定律应用于血管壁的物理平衡，提出了临界关闭压力的概念。这些结果在循环生理学家中是众所周知的，甚至在医学生的几本标准生理学教科书中也提到了这些结果。因此，到目前为止，包括本作者之一（15）在内的不少研究者都利用拉普拉斯定律来考虑中空器官的力学平衡，而没有对其适用性进行严格的考虑。然而，众所周知，拉普拉斯定律只适用于表面膜。因此，该定律是否适用于壁厚与管腔半径相比不够小的血管显然是有疑问的。在大动脉中，发现壁厚与内径的比率从6%到33%不等（13）。
AEUMA, TAKEHIKO, AND SYOTEN OKA. Mechanical equilibrium of blood vessel walls. Am. J. Physiol. 221 (5): 1310-1318. 1971.-The validity of applying the law of Laplace to the mechanical equilibrium of blood vessels was examined on the basis of our new general equation which holds for any hollow cylindrical tube in equilibrium under constant internal and external pressures. Theoretical considerations and experimental evidences revealed that the circumferential tension of minute blood vessel walls must be negative. Occurrence of such negative tension indicates that the wall is in a state of compression instead of stretching. As the negative tension under the positive transmural pressure cannot be supposed from the law of Laplace, the law should not be applied to these vessels even as an approximation of the general equation. The stability of mechanical equilibrium of the vessels was also discussed by utilizing the general equation. Whether closure of the lumen of an arteriole or a precapillary sphincter occurs is dependent only upon whether the developed active tension exceeds a critical value, and not upon whether the intravascular pressure is less than a critical value, ie, the critical closing pressure. Physical stability of microcirculation thus proved to be determined solely by vasomotor tone but not by transmural pressure. general equation for cylindrical tube; law of Laplace; circumferential tension; negative tension; critical closing pressure; active tension; elastic tension; transmural pressure; extravascular pressure; intravascular pressure; elastic diagram; equilibrium curveSINCE 195 1, Burton and his colleagues (4, 5, 8, 10, 14) have applied the law of Laplace to the physical equilibrium of vascular walls and proposed the concept of the critical closing pressure. These results have been well known among circulatory physiologists and mentioned even in several standard textbooks of physiology for medical students. Thus, not a few investigators, including one of the present authors (15), have so far utilized the law of Laplace for considering mechanical equilibrium of hollow organs, without critical considerations of its applicability. As generally known, however, the law of Laplace is valid only for a surface membrane. Accordingly, it is obviously questionable whether the law can be applied to a blood vessel where the thickness of the wall is not small enough compared to the radius of the lumen. The ratio of the wall thickness to the internal radius was found to vary from 6 to 33% in the large arteries (13).