Plasma lipids and physicochemical properties of the erythrocyte plasma membrane throughout pregnancy.

Background: The physiopathological relevance of plasma lipid concentrations is supported by the observation that they might affect the physicochemical properties of the plasma membrane of circulating cells and might be crucial in the pathological conditions complicating pregnancy.

Methods: Plasma and erythrocyte membrane lipid composition, membrane fluidity and function [membrane-bound enzyme sodium/potassium adenosine triphosphatase (Na+/K+-ATPase) activity] were studied in 24 healthy women in the nonpregnant condition and at 12, 24 and 38 weeks' gestation.

Results: The plasma showed an increase in total and high density lipoprotein (HDL) cholesterol, triglyceride (TG) and phospholipid (PL) levels. In the erythrocyte membrane we found the cholesterol/phospholipid (C/PL) ratio increased and the saturated to unsaturated fatty acid (FA) ratio (Sat/Unsat) significantly reduced; fluorescence polarization showed an initial increase during pregnancy and a progressive decrease afterwards; Na+/K+-ATPase activity was progressively reduced.

Conclusions: A generalized alteration in the composition and function of the maternal erythrocyte membrane is present during a physiological pregnancy, and these modifications may involve a more complex physiopathogenetic mechanism.