[Usefulness of vitamin A binding protein as a marker for capillary endothelial permeability]

We performed a preliminary study to assess the usefulness of Vitamin A binding protein (VABP) as a gamma-camera marker for capillary endothelial permeability. We used a guinea pig model of endotoxin (LPS) induced acute lung injury. We calculated the concentration ratio of either 125I-albumin or 125I-VABP in lung tissue to that in plasma (tissue plasma ratio; T/P) as a parameter of capillary endothelial permeability. 99mTc-diethylene triamine pentaacetic acid (DTPA) was used as a marker for pulmonary interstitial volume. We estimated wet to dry lung weight ratio as a parameter of lung water accumulation (W/D). LPS increased the T/P of 125I-albumin and W/D, suggesting the development of permeability edema. The T/P for 125I-VABP was also increased, indicating that 125I-VABP can be used to detect elevated capillary endothelial permeability. In both groups, LPS and saline, the T/P was higher for 125I-VABP than for 125I-albumin. These data suggest that the pulmonary capillary endothelium is more permeable to VABP than albumin.