Lecarpentier Yves, Claes Victor, Lecarpentier Edouard, Guerin Catherine, Hébert Jean-Louis, Arsalane Abdelilah, Moumen Abdelouahab, Krokidis Xénophon, Michel Francine, Timbely Oumar
Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France.
Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium.
PLoS One. 2014 Sep 30;9(9):e108814. doi: 10.1371/journal.pone.0108814. eCollection 2014.
Human placental stem villi (PSV) present contractile properties. In vitro mechanics were investigated in 40 human PSV. Contraction of PSV was induced by both KCl exposure (n = 20) and electrical tetanic stimulation (n = 20). Isotonic contractions were registered at several load levels ranging from zero-load up to isometric load. The tension-velocity relationship was found to be hyperbolic. This made it possible to apply the A. Huxley formalism for determining the rate constants for myosin cross-bridge (CB) attachment and detachment, CB single force, catalytic constant, myosin content, and maximum myosin ATPase activity. These molecular characteristics of myosin CBs did not differ under either KCl exposure or tetanus. A comparative approach was established from studies previously published in the literature and driven by mean of a similar method. As compared to that described in mammalian striated muscles, we showed that in human PSV, myosin CB rate constants for attachment and detachment were about 103 times lower whereas myosin ATPase activity was 105 times lower. Up to now, CB kinetics of contractile cells arranged along the long axis of the placental sheath appeared to be the slowest ever observed in any mammalian contractile tissue.
人胎盘干细胞绒毛（PSV）具有收缩特性。对40个人胎盘干细胞绒毛进行了体外力学研究。通过氯化钾暴露（n = 20）和电强直刺激（n = 20）诱导胎盘干细胞绒毛收缩。在从零负荷到等长负荷的几个负荷水平下记录等张收缩。发现张力-速度关系呈双曲线。这使得可以应用A.赫胥黎形式来确定肌球蛋白横桥（CB）附着和脱离的速率常数、CB单力、催化常数、肌球蛋白含量和最大肌球蛋白ATP酶活性。在氯化钾暴露或强直刺激下，肌球蛋白CB的这些分子特征没有差异。通过文献中先前发表的研究并采用类似方法建立了一种比较方法。与哺乳动物横纹肌中描述的情况相比，我们发现，在人胎盘干细胞绒毛中，肌球蛋白CB附着和脱离的速率常数低约103倍，而肌球蛋白ATP酶活性低105倍。迄今为止，沿胎盘鞘长轴排列的收缩细胞的CB动力学似乎是在任何哺乳动物收缩组织中观察到的最慢的。
