Ionic lanthanum passage across cerebral endothelium exposed to hyperosmotic arabinose

摘要: Hyperosmotic media infused into the cerebral circulation open blood-brain barrier to protein and colloid. The mechanism whereby such substances cross affected vessels is still disputed. We describe here transendothelial route taken by ionic lanthanum (La3+), a small electron-dense tracer which, unlike colloidal lanthanum, can be administered living animal. In adult rats, 2.9 ml of hyperosmotic (1.4 M) arabinose was internal carotid artery as 30-s bolus, followed 5 mM LaCl3. To find extravasated La3+, which invisible light microscopy, horseradish peroxidase (HRP) injected simultaneously femoral vein. treatment resulted in exudation both HRP La3+ primarily around arterioles. crossed arterioles through successive tight junctions between endothelial cells. Although were not discernibly opened, they must have become permeable because extracellular pools penetrated La3+. These are normally inaccessible Luminal abluminal pits cytoplasmic vesicles, some them containing formed intraendothelial clusters. Their role, if any, transfer ion remains uncertain.