Nádasy G L, Monos E, Mohácsi E, Kovách A G
Experimental Research Department, Semmelweis University Medical School, Budapest, Hungary.
Acta Physiol Hung. 1988;71(3):347-61.
Incongruency between the upward and downward routes of pressure-radius curves, a phenomenon called hysteresis, was studied on 124 human umbilical arterial segments. Such characteristic phenomena were found which are unusual if one compares them to the viscotic hysteresis of the unliving material. After a stay at low distending pressure, the loop of the forthcoming pressure-radius cycle became exceptionally wide. The width of the loop was relatively independent of the rate of pressure change. Equilibrium points were not always inside the loop. Addition of a smooth muscle contracting agent increased the width of the loop. At low pressure the segments contracted spontaneously and the shortened elements kept the shortened length for some time even at higher distending pressure. All phenomena found in connection with hysteresis can be explained if we suppose that some of the contractile elements contract during cyclic stretching relatively easily at low distending pressures. Due to the "catchlike" properties of this contraction, the shortened elements could resist against higher distending forces on the upward route and this way a delay in the dilatation process occurred. This made upward and downward routes different.
在124个人类脐动脉节段上研究了压力-半径曲线的上升和下降路径之间的不一致性，即一种称为滞后现象的现象。发现了这样一些特征性现象，如果将它们与无生命物质的粘性滞后现象相比较，这些现象是不寻常的。在低扩张压力下停留后，即将到来的压力-半径循环的环变得异常宽。环的宽度相对独立于压力变化率。平衡点并不总是在环内。添加平滑肌收缩剂会增加环的宽度。在低压下，节段会自发收缩，即使在较高的扩张压力下，缩短的部分也会在一段时间内保持缩短的长度。如果我们假设一些收缩元件在循环拉伸过程中在低扩张压力下相对容易收缩，那么与滞后现象相关的所有现象都可以得到解释。由于这种收缩的“捕捉样”特性，缩短的部分在上升路径上可以抵抗更高的扩张力，从而导致扩张过程出现延迟。这使得上升和下降路径不同。
