Premium
Cellular permeation pathways in a leaky epithelium: the human amniochorion
Author(s) -
Hardy Marcos A.,
Leonardi Ronald T.,
Scheide John I.
Publication year - 1989
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1111/j.1768-322x.1989.tb00828.x
Subject(s) - amnion , biology , amiloride , transepithelial potential difference , biophysics , transcellular , permeation , epithelium , ouabain , membrane potential , membrane , ion transporter , biochemistry , fetus , sodium , chemistry , pregnancy , genetics , organic chemistry
The presence of cellular permeation pathways in human fetal membranes at term was evaluated. Electrical parameters (transepithelial potential [TEP], and conductance [G t ], and intracellular potentials [cell PD]), and water and urea diffusional coefficients (Pdw, Pdu), were determined in Ussing‐like chambers. In amniochorion, the TEP was practically 0 (0.1±0.03 mV), and the G t very high (144±14 mS/cm 2 ). The Cell PD of amnion cells was −37±3 mV. Increasing the [K + ] of the amniotic perfusate between 5.8 and 125.8 mM depolarized the cells with a slope of 23 mV. The deletion of Na + hyperpolarized the cells, whereas amiloride and ouabain depolarized them. The Pdw and Pdu were determined in intact amnion and chorion and in their epithelial cell layers. The Pdw/Pdu ratio in amnion was 4.0, and 7.0 in its cell layer; the ratio in chorion was 2.5, and 3.3 in its cell layer. The amniochorion is a leaky structure, but its cellular layers possess definite transcellular permeation pathways. The ionic conductances in amnion cells are complex, with the Cell PD being determined by at least K + and Na + conductances, and ouabain‐ and amiloride‐sensitive pathways. The amnion is a more effective diffusional barrier to water and urea than chorion is; its diffusional characteristics are comparable to those of nystatin‐treated lecithin: cholesterol bilayers and the membranes of human erythrocytes.