Distribution of sialoglycoconjugates on the luminal surface of the endothelial cell in the fenestrated capillaries of the pancreas

Sialic acid-bearing molecules on the luminal surface of the vascular endothelium in mouse and rat pancreatic capillaries were detected electron microscopically by using a procedure with ferritin hydrazide (FH), after preferential oxidation of sialyl residues with sodium periodate. The distribution of FH on the endothelial surface demonstrated the existence of microdomains with various densities of sialoglycoconjugates oxidizable by sodium periodate and accessible to the tracer. On the plasmalemma proper, FH binding sites were heterogeneously distributed. Their concentration on various microdomains decreased as follows: plasmalemma proper greater than coated pits greater than stomal diaphragms of plasmalemmal vesicles and transendothelial channels, and fenestral diaphragms. The membrane of plasmalemmal vesicles and transendothelial channels was not labeled by FH. Nonspecific binding of FH to the nonoxidized endothelial surface or that oxidized after neuraminidase treatment was relatively low.     

Myocardial lesions in experimental acute heart failure

The present study concerns the morphological and biochemical lesional picture of the myocardium in cases of acute heart failure induced by various experimental models: ligature of the coronary artery, direct electric stimulation of the heart by catheterism, lethal hemorrhage, pneumothorax, beta-adrenergic shock. Worthy of note was the similitude of the lesional myocardium pictures characterized electron microscopically by a wide range of lesions, from reversible to focal cytolysis, and biochemically by decrease of mitochondrial enzymes, ATP, Mg2-1 X K+ and increase of Na+ X H2O, Ca2+. Problems linked to the pathogenesis, reversibility of the lesions and efficiency of certain therapeutical means are discussed.