Effect of anticoagulation upon nephron obstruction in experimental acute ischaemic renal failure. A morphological study

Ischaemic‐reperfusion injury as a model of acute renal failure (ARF) results in increased macromolecular permeability, tubular obstruction, and renal oedema. To investigate the role for coagulation in this model, anticoagulated and saline‐pretreated rats were subjected to 60 min unilateral renal artery occlusion (RAO). After 15 min of reflow, specimens were collected for electron and light microscopic examination. Morphometry was employed to study podocyte changes and Bowman's space dilatation as measures of increased permeability and tubular obstruction, respectively. After 15 min of reflow, Bowman's space increased significantly and the podocytes were markedly widened and flattened. Rats pretreated with heparin or warfarin showed less widening of Bowman's space than saline‐treated rats, whereas no significant difference was seen regarding the podocyte changes. In saline‐treated rats, fibrin‐positive material was seen in the tubules but not in the urine sediments collected after 90 min of reflow, either due to fibrinolysis or poor urinary elimination. The results suggest that anticoagulation does not preclude the glomerular sieving of macromolecules, but seems to reduce tubular obstruction, probably by preventing conversion of filtered fibrinogen into fibrin.