PHYSIOCHEMICAL CHARACTERISTICS OF PLACENTAL TRANSFER

Abstract : A biophysicochemical model of certain maternalfetal circulatory and metabolic relations was constructed for the purpose of simulating the composition and the transfer of respiratory gases and other elements across the placental membrane. The model was subsequently analyzed by a mathematical method for the minimization of a chemical free-energy function subject to constraints relating to mass, charge and phase transfer. As a preliminary investigation of the placental phenomenon, the model was applied to the representation of the exchanges of respiratory gases occurring between the venous and arterial sides of the total air-blood system. Some interestingly close similarities were obtained between the model results and physiological measurements. In addition, the model indicates a greater acidity for the fetal than for the maternal erythrocyte intracellular medium. This feature, combined with other aspects of the results, could explain in part the reported low oxygen saturation of fetal hemoglobin in utero. (Author)