Sm. Vogel et al., Albumin uptake and transcytosis in endothelial cells in vivo induced by albumin-binding protein, AM J P-LUNG, 281(6), 2001, pp. L1512-L1522
Citations number
37
Categorie Soggetti
da verificare
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY
The 60-kDa endothelial cell surface albumin-binding glycoprotein (gp60) is
postulated to be a docking site for albumin that mediates the uptake of alb
umin and its transport in cultured microvessel endothelial cells. In the pr
esent study, we used an isolated Krebs-perfused rat lung preparation to add
ress the in vivo role of gp60 in mediating albumin uptake and transport. Ad
dition of primary anti-gp60 antibody to the perfusate followed by the secon
dary antibody to cross-link gp60 increased the vessel wall I-125-albumin pe
rmeability-surface area (PS) product 2.5-fold without affecting the capilla
ry filtration coefficient (K-f,K-c; a measure of liquid permeability). In c
ontrast, EDTA (5 mM), which induces interendothelial gap formation, produce
d parallel increases in both K-f,K-c and I-125-albumin PS product. Increasi
ng perfusate albumin concentration to >1 g/100 ml (EC50 1.2 g/100 ml) was s
ufficient to block I-125-albumin PS product, indicating that the perfusate
albumin competed with tracer albumin for transendothelial albumin transport
. Cross-linking of gp60 in lungs perfused with saturating concentration of
albumin resulted in a greater increase in I-125-albumin PS product, indicat
ing that gp60 function was capable of being modulated. These results show t
hat activation of gp60 in pulmonary microvessels induces albumin uptake and
its transport through a nonhydraulic pathway that fits with a model of alb
umin permeability via the transcellular pathway.