title: Transcytosis of alpha1-acidic glycoprotein in the continuous microvascular endothelium.
abstract: By using perfusions and bolus administration, coupled with postembedding immunocytochemical procedures, we have identified the structures involved in the transport of derivatized orosomucoid (alpha1-acidic glycoprotein) across the continuous microvascular endothelium of the murine myocardium. Our findings indicate that: (i) monomeric orosomucoid binds to the luminal surface of the endothelium; (ii) it is restricted to caveolae during its transport across the endothelium; (iii) it is detected in the perivascular spaces at early time points (by 1 min) and in larger quantities at later time points (>5 min) from the beginning of its perfusion or its intravascular administration; (iv) no orosomucoid molecules are found in the intercellular junctions or at the abluminal exits of interendothelial spaces; and (v) the vesicular transport of orosomucoid is strongly inhibited by N-ethylmaleimide (>80%). Because, by size and shape, the orosomucoid qualifies as a preferential probe for the postulated small pore system, our results are discussed in relation to the pore theory of capillary permeability.
authors.affiliation: Division of Cellular and Molecular Medicine, University of California at San Diego, School of Medicine, La Jolla, CA 92093, USA.
authors.forename: D
authors.initials: D
authors.lastname: Predescu
authors.forename: S
authors.initials: S
authors.lastname: Predescu
authors.forename: T
authors.initials: T
authors.lastname: McQuistan
authors.forename: G E
authors.initials: GE
authors.lastname: Palade
mesh_terms: D000818:Animals; D001692:Biological Transport; D002199:Capillary Permeability; D003331:Coronary Vessels / Q000378:metabolism* / Q000648:ultrastructure*; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000648:ultrastructure*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009961:Orosomucoid / Q000378:metabolism*
chemical_list: D009961:Orosomucoid