title: Statistical Mechanics of the Human Placenta: A Stationary State of a Near-Equilibrium System in a Linear Regime.
abstract: All near-equilibrium systems under linear regime evolve to stationary states in which there is constant entropy production rate. In an open chemical system that exchanges matter and energy with the exterior, we can identify both the energy and entropy flows associated with the exchange of matter and energy. This can be achieved by applying statistical mechanics (SM), which links the microscopic properties of a system to its bulk properties. In the case of contractile tissues such as human placenta, Huxley's equations offer a phenomenological formalism for applying SM. SM was investigated in human placental stem villi (PSV) (n = 40). PSV were stimulated by means of KCl exposure (n = 20) and tetanic electrical stimulation (n = 20). This made it possible to determine statistical entropy (S), internal energy (E), affinity (A), thermodynamic force (A / T) (T: temperature), thermodynamic flow (v) and entropy production rate (A / T x v). We found that PSV operated near equilibrium, i.e., A ≺≺ 2500 J/mol and in a stationary linear regime, i.e., (A / T) varied linearly with v. As v was dramatically low, entropy production rate which quantified irreversibility of chemical processes appeared to be the lowest ever observed in any contractile system.
authors.affiliation: Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Lecarpentier
authors.affiliation: Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium.
authors.forename: Victor
authors.initials: V
authors.lastname: Claes
authors.affiliation: Institut de Cardiologie, Hôpital de la Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Hébert
authors.affiliation: Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France.
authors.forename: Xénophon
authors.initials: X
authors.lastname: Krokidis
authors.affiliation: Service de Pneumologie, Centre Hospitalo-Universitaire de Nantes, Nantes, France.
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Blanc
authors.affiliation: Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France.
authors.forename: Francine
authors.initials: F
authors.lastname: Michel
authors.affiliation: Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France.
authors.forename: Oumar
authors.initials: O
authors.lastname: Timbely
mesh_terms: D002824:Chorionic Villi / Q000502:physiology*; D004558:Electric Stimulation; D004574:Electromagnetic Fields; D019277:Entropy; D005260:Female; D006801:Humans; D016014:Linear Models; D015233:Models, Statistical; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000502:physiology; D054792:Muscle, Striated / Q000502:physiology; D010920:Placenta / Q000502:physiology*; D011247:Pregnancy; D011336:Probability; D013696:Temperature; D013816:Thermodynamics