FLUORESCEIN-LABELED DEXTRAN CONCENTRATION IS INCREASED IN BAL FLUID AFTER ANTU-INDUCED EDEMA IN RATS

Several methodologies have been developed to assess alveolocapillary m embrane permeability in acute lung injury. The purpose of this study w as to determine the reliability of FITC-dextran compared with radioact ive tracers to assess lung permeability alterations. After intraperito neal administration of alpha-naphthylthiourea (ANTU, 50 mg/kg) or DMSO -ANTU vehicle, the animals were euthanized and their lungs were studie d in an isolated-lung preparation. FITC-dextran or radiolabeled tracer s were added to the perfusate. At 2 h the bronchoalveolar lavage (BAL) fluid from the ANTU group showed a significantly greater amount of fl uorescence in the supernatant after centrifugation of BAL fluid compar ed with the DMSO group. Consistent results were observed with the radi oactive tracers: there was an increase in extravascular albumin space and extravascular lung water compared with the control group. No cleav age of the FITC from the dextran molecule was evident by chromatograph y comparing samples recovered from the BAL fluid to the pure FITC-dext ran molecule. In conclusion, measurement of FITC-dextran in the supern atant of BAL fluid after intravascular administration is a reliable me thod of assessing lung permeability changes in vivo and ex vivo.