title: Effect of perfusate hematocrit on urea permeability-surface area in isolated dog lung.
abstract: Seven dog lower left lung lobes were statically inflated and perfused at a constant rate for each lobe with a perfusate in which the hematocrit was altered over a wide range. The permeability-surface area of urea was calculated from multiple indicator dilution curves using two separate injectates for each hematocrit level. One injectate contained only 125I-albumin as the vascular reference tracer and the other contained both 51Cr-erythrocytes and 125I-albumin as the vascular reference tracers; both contained [14C]urea as the permeating tracer. The results strongly indicate that the phenomenon of "erythrocyte trapping" of urea does not affect the calculation of urea permeability-surface area product provided the appropriate albumin-erythrocyte composite reference tracer is utilized in its calculation.
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes; D002463:Cell Membrane Permeability; D002860:Chromium Radioisotopes; D004285:Dogs; D004912:Erythrocytes / Q000502:physiology; D006400:Hematocrit; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008168:Lung / Q000502:physiology*; D010477:Perfusion; D013499:Surface Properties; D014508:Urea / Q000378:metabolism*
chemical_list: D002250:Carbon Radioisotopes; D002860:Chromium Radioisotopes; D007457:Iodine Radioisotopes; D014508:Urea