Albumin binding sites are expressed on the abluminal plasma membrane of capillary endothelium.

The presence of albumin binding sites on the abluminal front of vascular endothelium was examined on the capillaries of the adipose tissue. The experimental procedure consisted in injecting interstitially within the rat epididymal fat and epicardial fat, albumin (alone or bearing oleic acid) either conjugated with gold particles (Alb-Au or Alb-OA-Au) or radioiodinated [( 125I]-Alb). In controls, polyethyleneglycol-gold complex (PEG-Au) and [125I]-IgG were used as tracers.

Identification of albumin-binding proteins in capillary endothelial cells.

Isolated fat tissue microvessels and lung, whose capillary endothelia express in situ specific binding sites for albumin, were homogenized and subjected to SDS-gel electrophoresis and electroblotting. The nitrocellulose strips were incubated with either albumin-gold (Alb-Au) and directly visualized, or with [125I]albumin (monomeric or polymeric) and autoradiographed. The extracts of both microvascular endothelium and the lung express albumin-binding proteins (ABPs) represented by two pairs of polypeptides with major components of molecular mass 31 and 18 kD.

Alterations of phospholipid asymmetry in the membrane of spontaneously aggregated platelets in diabetes.

The changes of asymmetric distribution of anionic phospholipids of human platelets in diabetic patients were studied by fluorescent and freeze fracture cytochemistry, using merocyanine 540 (MC 540) and polymyxin B (PxB) as specific markers. The membrane anionic phospholipids were detected with PxB, a membrane nonpermeant probe, used either in native form for freeze fracture electron microscopy or as dansylated or iodinated derivative for fluorescence microscopy or gamma counting, respectively. MC 540 is a naturally fluorescent probe which reportedly inserts into less packed bilayer domains.

The cerebral microvasculature of the rat: structure and luminal surface properties during early development.

The development of the cerebral microvasculature of the rat was studied during three successive postnatal periods, namely: 1) neonatal period, i.e., 1 to 9 days after birth (capillary sprouting period); 2) myelinization period, i.

Specific binding sites for albumin restricted to plasmalemmal vesicles of continuous capillary endothelium: receptor-mediated transcytosis.

The interaction of homologous and heterologous albumin-gold complex (Alb-Au) with capillary endothelium was investigated in the mouse lung, heart, and diaphragm. Perfusion of the tracer in situ for from 3 to 35 min was followed by washing with phosphate-buffered saline, fixation by perfusion, and processing for electron microscopy. From the earliest time examined, one and sometimes two rows of densely packed particles bound to some restricted plasma membrane microdomains that appeared as uncoated pits, and to plasmalemmal vesicles open on the luminal front.