Non‐electrolyte solute permeabilities of human placental microvillous and basal membranes.

Abstract

1. Permeability to non‐electrolytes of isolated microvillous and basal membranes from human term placenta was measured using stopped‐flow light‐scattering techniques. The studied solutes were urea, ethylene glycol, glycerol, creatinine, erythritol, arabitol and mannitol. 2. At 37 degrees C, permeability of the microvillous membrane to mannitol and urea was 0.30 +/‐ 0.02 x 10(‐6) cm/s (mean +/‐ S.E.M.) and 3.2 +/‐ 0.2 x 10(‐6) cm/s, respectively. The corresponding permeabilities for the basal membrane were 1.2 +/‐ 0.1 x 10(‐6) cm/s (mannitol) and 4.4 +/‐ 0.3 x 10(‐6) cm/s (urea). The basal membrane was substantially more permeable to hydrophilic solutes than the microvillous membrane. This is probably due to differences in lipid composition, as illustrated by membrane cholesterol content, which was found to be approximately 50% lower in the basal as compared to the microvillous membrane. 3. Similarities between permeabilities in placental membranes and lipid bilayers and the linear relationship noted between solute hydrophobicity and placental permeability suggested that solutes permeate both human syncytiotrophoblast membranes by a solubility/diffusion mechanism. In the microvillous membrane this was supported by data obtained for activation energies (> 10 kcal/mol) and reflection coefficients (close to 1). In the basal membrane, low activation energies for glycerol and urea and a low reflection coefficient for urea indicated that these solutes may, in part, share a common pathway with water. 4. It was estimated that the placental permeability to molecules with a molecular weight under 200 observed in vivo can, to a great extent, be accounted for by transcellular permeation.

Asymmetric Syncytial Expression of GLUT9 Splice Variants in Human Term Placenta and Alterations in Diabetic Pregnancies

“…Microvillous membrane and BM vesicles were prepared according to methods described previously. 2,20 The only modification was the inclusion of protease inhibitory components (0.5 mmol/L ethylenediamine tetraacetate, 0.5 mg/mL aprotinin, and 0.5 mg/mL leupeptin) in the standard preparative buffer (250 mmol/L sucrose and 10 mmol/L HEPES/Tris, pH 7.4). Microvillous membrane and BM fractions were stored at À80 C until use.…”

Na+-K+-ATPase is distributed to microvillous and basal membrane of the syncytiotrophoblast in human placenta

“…Although methods for separating the MVM from the BM have been available for several years (5,18,23), the distribution of Na ϩ -K ϩ -ATPase activity and protein between these membrane surfaces remains to be established. In the present study, MVM and BM were isolated using the procedure described by Illsley and co-workers (18)(19)(20), a technique by which both synctiotrophoblast plasma membrane fractions are obtained from the same placenta. Na ϩ -K ϩ -ATPase activity was measured using 3-O-methylfluorescein phosphate (3-O-MFP), and the isoform distribution of Na ϩ -K ϩ -ATPase subunits was characterized by Western blotting.…”

Intraserebral Hemorrage During Pregnancy: Case Report

“…Multiple courses of antenatal corticosteroids should be used cautiously while weighing the risks and benefits in each individual case (18) . Bain et al, Jahnsson et and Basso et al, reported that mannitol (molecular weight 182) which is inert, uncharged, hydrophilic molecule believed to cross the placenta and other epithelia by passive diffusion (19,20,21) . In our case, in guidance of literatures, AEDs, steroids and mannitol were not used for potential adverse effects on fetus.…”