Arsalane, Abdelilah

Claes, Victor

Guerin, Catherine

Hebert, Jean-Louis

Krokidis, Xenophon

Lecarpentier, Edouard

Lecarpentier, Yves

Michel, Francine

Moumen, Abdelouahab

Timbely, Oumar

Abstract: 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 10(3) times lower whereas myosin ATPase activity was 10(5) 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

Institutional Repository Universiteit Antwerpen

Ultraslow Myosin Molecular Motors of Placental Contractile Stem Villi in Humans

Ultraslow Myosin Molecular Motors of Placental Contractile Stem Villi in Humans

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Institutional Repository Universiteit Antwerpen