KIDNEY PRESSURES AFTER TEMPORARY RENAL-ARTERY OCCLUSION IN RAT

Acute kidney failure was produced in the anesthetized rat by 1 h of complete renal artery occlusion. Kidney function was studied either immediately after release of the occlusion or 1 day later using clearance, micropuncture, histological and nephron dissection techniques. Polyfructosan clearance was decreased to 5% of normal after temporary occlusion. Proximal tubular pressure (PTP) averaged 13-14 mm Hg in normal kidneys, 39 mmHg immediately after release of unilateral occlusion, 19 mmHg 1 day after unilateral occlusion and 25 mm Hg 1 day after bilateral occlusion. The increased PTP reduces the glomerular filtration rate (GFR). Glomerular capillary pressure, estimated from the sum of the stop-flow and arterial plasma colloid osmotic pressures, was not decreased after temporary ischemia. Single-nephron GFR, measured without intratubular pressure control, was only slightly below normal 1 day after bilateral occlusion. Most distal tubules from ischemia-damaged kidneys contained hyaline casts. Tubular obstruction is a major factor in this model of acute kidney failure.