The binding of cationic probes to apical and basal surfaces of rat lung capillary endothelium and of endothelial cells in tissue culture.
The reasons for greater lung vascular permeability to anionic macromolecules are not understood. In order to determine whether the luminal or abluminal surfaces of lung capillary endothelial cells differ with respect to surface charge, we compared the binding of cationic ferritin, an electron dense probe, with these cell surfaces in lung capillaries. Because lung capillaries are not normally permeable to cationic ferritin, lungs were examined from rats with increased permeability edema caused by pretreatment with alpha-naphthylthiourea (ANTU). We found that more cationic ferritin particles bound to the luminal than to the abluminal surfaces of lung capillary endothelium. In order to determine whether this was due to inaccessibility of cationic ferritin to the lung interstitium, we also compared cationic ferritin binding to the apical and basal surfaces of bovine calf aortic and main pulmonary arterial endothelial cells in tissue culture. We found that more cationic ferritin bound to the apical than to the basal surface of the cultured cells. The binding of cationic ferritin to cultured endothelial cells was due to charge since native, anionic ferritin did not bind to either surface and binding was decreased by neuraminidase pretreatment of cultures. Cultures incubated with thiourea, another thiocarbamide that causes increased permeability edema in vivo, also showed greater binding of cationic ferritin to the apical cell surface, suggesting that the differences seen in vivo were not due to thiocarbamide injury. However, another cationic probe, ruthenium red, bound to both the apical and basal surfaces of cultured endothelial cells. These results suggest that the basal endothelial cell surface does not lack anionic sites.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D002196:Capillaries / Q000166:cytology / Q000378:metabolism; D046508:Culture Techniques; D004727:Endothelium / Q000166:cytology / Q000378:metabolism; D005293:Ferritins / Q000378:metabolism*; D008171:Lung Diseases / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D008297:Male; D010477:Perfusion; D011652:Pulmonary Circulation; D051381:Rats; D011919:Rats, Inbred Strains; D012428:Ruthenium / Q000378:metabolism*; D012430:Ruthenium Red / Q000378:metabolism*; D013890:Thiourea / Q000031:analogs & derivatives
C010297:polycationic ferritin; D012430:Ruthenium Red; D012428:Ruthenium; D005293:Ferritins; D013890:Thiourea; C005277:alpha-naphthyl thiourea