Crotty T P
Anatomy Department, University College, Cork, Ireland.
Med Hypotheses. 1991 Mar;34(3):243-51. doi: 10.1016/0306-9877(91)90218-n.
When noradrenaline, either endogenous or exogenous, is released from the venae venarum of a dog's lateral saphenous vein which is constricted by noradrenaline, it dilates the vein. By limiting the release of the drug to just a section of the vein's venae venarum network it is possible to dilate the normal vein segmentally, that is, cause varicosities. This has led to the suggestion that pathological varicosities begin as localised physiological dilator responses of the vein wall to circulating endogenous noradrenaline, released from the vein's venae venarum. Under ambulatory conditions small quantities of noradrenaline probably flow almost continually from the lumen of the vein to different parts of its venae venarum network and serve to adjust constrictor tone downwards. When there is turbulence in the vein lumen the volume of reflux becomes excessive and causes so much adjustment that constrictor tone is abolished. The vein, in effect, then exhibits a frank dilator effect, visible as a varicosity, localised to the level in the vein at which the turbulence occurs. If a high volume of hypoxic blood reflux continues for a critical period then the wall of the varicosity suffers secondary degenerative structural changes which make the varicosity permanent.
当内源性或外源性去甲肾上腺素从被去甲肾上腺素收缩的犬隐外侧静脉的静脉属支释放时，它会使该静脉扩张。通过将药物释放限制在静脉属支网络的仅一部分，有可能使正常静脉节段性扩张，即导致静脉曲张。这引发了一种观点，即病理性静脉曲张始于静脉壁对从静脉属支释放的循环内源性去甲肾上腺素的局部生理性扩张反应。在动态条件下，少量去甲肾上腺素可能几乎持续地从静脉腔流向其静脉属支网络的不同部位，并用于向下调节收缩张力。当静脉腔内出现湍流时，反流的量会变得过多，导致过多的调节，从而使收缩张力消失。实际上，静脉随后会表现出明显的扩张效应，表现为静脉曲张，局限于静脉中出现湍流的水平。如果大量低氧血液反流持续一段关键时期，那么静脉曲张的壁会遭受继发性退行性结构变化，使静脉曲张永久化。
