The Roles of Small Molecules as Probes of Endothelial Barrier Function in the Lung: Novel Measurement Methods and Molecular Probes

Dysfunction of the barrier properties of endothelial cells is implicated in a number of vascular diseases. One of the more prominent problems is the edema of the lungs seen with Adult Respiratory Distress Syndrome (1,2). Fluid accumulates in the lungs of such patients even though pulmonary pressures are relatively normal. Experimental and patient studies suggest that the primary defect is an increased permeability of the lung vascular capillaries to fluid and macromolecules (3,4,5,6). A variety of methods have been used to assess such malfunctions in experimental animal models of ARDS and in patients. These range from straightforward measurements of lung water by post mortem desiccation and weighing to experimental measurement of lung lymph flow and analysis of protein content as compared to plasma protein concentration.