Cross-linked hemoglobin increases fractional reabsorption and gfr in hypoxic isolated perfused rat kidneys. Baines, A. D., B. Christoff, D. Wicks, D. Wiffen, and D. Pliura. Department of Clinical Biochemistry, University of Toronto and Hemosol Inc.
APStracts 2:0062F, 1995.
We compared the ability of human red blood cells and a cell-free oxygen carrier to maintain isolated perfused kidney function under moderately hypoxic conditions. Recirculating perfusate was gassed initially with 93% air/7% CO2 and after 30 minutes the gas was changed to 12% O2/7% CO2/81% N2. Oxygen content of the perfusate was increased with one of RBC (30 g/L Hbg) or highly purified human hemoglobin A0 (HbA0) polymerized with O-raffinose (o-R-poly Hb, 30 g/L Hbg). For comparison kidneys were perfused with 60 g/L of bovine serum albumin (BSA) alone. The effects of unmodified hemoglobin were examined by adding 5g/L of non-polymerized HbA0 to the BSA perfusate after 20 min. The effect of increasing oxygen delivery without hemoglobin was examined by switching to 93% oxygen after 20 min during some BSA perfusions (BSA-HiO2). Vascular resistance decreased progressively in o-R-poly Hb and BSA-Hi02 perfused kidneys but remained constant in other experiments. L-NAME prevented vasodilation and increased the filtration fraction of o-R-poly Hb perfused kidneys with no change in other functions. L-NAME also prevented the formation of methemoglobin. After 70 min perfusion with BSA Na reabsorption was 82+/-3 % (SD) and inulin clearance (GFR) was 0.66+/ -0.33 mL/min.g. RBC increased reabsorption to 95 %(85-98) (median, 25th-75th percentile) but did not alter GFR (0.52+/-0.26 ml/min.g). o-R-poly Hb increased Na reabsorption proportionately more than GFR so that while GFR was doubled to 1.04+/-0.40 mL/min.g Na reabsorption increased to 98 % ( 92-99.5). HbA0 increased GFR to 1.07+/-0.44 mL/min.g and reabsorption to 89+/-6 %. A similar increase in Na reabsorption (93+/-2%) and GFR (1.38+/-0.3) was produced by increasing O2 content of BSA with 93% oxygen. o-R-poly Hb was most effective in raising and maintaining overall renal function and lowering urine Na concentration and protein excretion. 

Received 6 September 1994; accepted in final form 12 April 195.
APS Manuscript Number F319-4.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.