van Duyl W A, Coolsaet B L
Urology. 1982 Jul;20(1):53-8. doi: 10.1016/0090-4295(82)90538-6.
Contractions were chemically induced in vitro in pig uterus segments by a high potassium concentration in a metabolic solution. Slow contractions were found mainly in the transverse direction. The near absence of contractions in the longitudinal direction is ascribed to a nearly circular orientation of the muscle fibers. (In terms of the helical muscle-fiber model of the ureter, our findings would correspond to a pitch of 3 to 5 degrees for the helix.) It is further postulated that the coupling structure of fibers in the transverse direction, determining an annular contraction mode, differs from that in the longitudinal direction, determining the longitudinal propagation of the annular contraction mode. The over-all conclusions on the basis of our results is that the helical muscle-fiber model now generally assumed for the ureter must be greatly modified to correlate with the experimental facts that its continued use is misleading and undesirable.
在代谢溶液中，通过高钾浓度在体外化学诱导猪子宫段收缩。发现缓慢收缩主要发生在横向方向。纵向几乎没有收缩归因于肌纤维几乎呈圆形排列。（根据输尿管的螺旋肌纤维模型，我们的发现相当于螺旋的螺距为3至5度。）进一步推测，决定环形收缩模式的横向纤维耦合结构与决定环形收缩模式纵向传播的纵向纤维耦合结构不同。基于我们的结果得出的总体结论是，目前普遍认为的输尿管螺旋肌纤维模型必须进行大幅修改，以与实验事实相符合，因为继续使用该模型会产生误导且不合适。
