An in vitro system for measuring endothelial permeability under hydrostatic pressure.
A system was developed, using early passage porcine aortic endothelial cells cultured on a microporous substratum mounted in a two-compartment chamber. It allows the application of a transendothelial pressure gradient and quantitative measurement of the resulting flow rate of fluid. Initial application of a hydrostatic pressure gradient of 20 mmHg resulted in a continuous decrease in the flow rate which reached a steady state after a period of 1-3 h. Further variations in the pressure resulted in pressure-dependent increase or decrease in the flow rate. The physiological relevance of this response is supported by the fact that decrease in permeability occurred only in the presence of Ca2+ ions. Removal of Ca2+ from a monolayer by EGTA led to an immediate increase in the flow rate, whereas readdition of Ca2+ in concentrations between 0.5 and 20 mM was observed to cause a concentration-dependent decrease in flow rate. Initial application of pressure with Ca2+-free medium failed to produce permeability changes of the cultured endothelium. These findings indicate that the permeability of a cultured endothelium to water and solutes is pressure- and Ca2+-dependent.
D000818:Animals; D001011:Aorta / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D004533:Egtazic Acid / Q000494:pharmacology; D004727:Endothelium / Q000502:physiology*; D011312:Pressure; D013552:Swine
D004533:Egtazic Acid; D002118:Calcium