Permselectivity of the glomerular wall examined with iron compound tracer

Rat kidney endothelial cell morphology was examined after introducing iron colloid particles of positive or negative charge to investigate the relationship between the electric charge and permeation through the glomerular capillary. The kidneys were first perfused with Hanks' solution through the renal arteries and then with iron colloid particles of positive or negative charge. The iron colloid particles of positive charge were prepared with ferric chloride and cacodylate solutions, and the negative particles were prepared with iron chondroitin sulfate colloid particles. The iron colloid particles of positive charge adhered to the surface of endothelial cells of the glomerular capillaries, as well as the arterioles, capillaries and venules. Some particles were taken up by pinocytosis, accumulated in the glomerular basement membrane and appeared in the urinary spaces passing through the filtration slits of podocytes. Iron colloid particles of negative charge neither adhered to the endothelial cells nor were taken by the cells. They did not permeate into the urinary spaces. Permeation into the tubular lumen through the peritubular venules was not observed with particles of positive or negative charge.