Hydraulic conductivity of endothelial cell monolayers cultured on human amnion

Hydraulic conductivity (L(p)) of endothelial cell monolayers cultured on a supporting matrix of human amnion was measured. Bovine aortic (Baec), bovine microvascular (Bmec), and human umbilical vein endothelial cell (Huvec) monolayers were mounted in a water-jacketed chamber maintained at 37°C. The lower compartment of the chamber was connected to an electronic sensor-aspiration system that served to volume clamp the lower compartment. The aspirated volume was displayed on a chart recorder, providing continuous measurements of volume flow per unit area (J(v)). In 36 monolayers, J(v) was linearly related to hydrostatic pressure. The average slope of this relationship (L(p)) was 1.14 ± 0.8 x 10^-6, 1.67 ± 1.49 x 10^-6, and 2.9 ± 0.85 x 10^-6 cm·s^-1·cmH₂O^-1 for Baec, Bmec, and Huvec, respectively. The effect of increased luminal oncotic pressure was studied in seven monolayers. The oncotic pressure difference (Δπ) ranged from 3.1 to 7.1 cmH₂O (measured with a Wescor oncometer). In all cases, there was an immediate fall in J(v) and a displacement to the right of the x-intercept of the line J(v) vs. change in pressure (ΔP) without a change in the slope (L(p)). These results indicate that the L(p) of endothelial cell monolayers cultured on amnion is within the range of values previously reported for single capillaries in vivo and that these monolayers appear to sustain Δπ sufficient to generate an osmotically driven water flow.