Effect of erythrocytes and globulin on renal functions of the isolated rat kidney.

We assessed the effects in isolated perfused rat kidneys of adding globulin or erythrocytes to Krebs-Henseleit bicarbonate perfusate with albumin as its principal source of colloid osmotic pressure during 3 h of perfusion. Colloid osmotic pressure varied between 11 and 58 mmHg. Bovine or human immunoglobulin substituted in part for albumin produced vasodilation, whereas rat erythrocytes added to albumin at a 5% hematocrit caused vasoconstriction. Inclusion of both globulin and erythrocytes in the perfusate was associated with an intermediate response. Kidneys perfused with albumin alone showed progressive decline in GFR, increasing vascular resistance, and increasing proteinuria correlating with kidney weight gain during perfusion. Onset of GFR and resistance changes were delayed and their magnitude decreased by increasing oncotic pressure. Estimated glomerular filtrate protein concentration of albumin-perfused kidneys progressively increased from 20 to 150 mg/dl. The presence of erythrocytes or globulin in the perfusate prevented the increase in vascular resistance and reduced the degree of decrease in GFR seen with albumin alone in the perfusate and reduced the time-dependent increase in proteinuria by 80%. The effects of globulin and erythrocytes on proteinuria were additive. The prevention of changes in hemodynamics, glomerular filtration, macromolecular clearance, subcapsular fluid accumulation, and organ weight gain for up to 5 h of perfusion by adding erythrocytes and globulins to the albumin perfusate suggest that these agents may be necessary for preventing interstitial edema and for maintaining renal function in vitro.