Intravascular retention and renal handling of purified natural and intramolecularly cross-linked hemoglobins

Plasma half time of unmodified hemoglobin (UHb) and two intramolecularly cross-linked hemoglobins (ααXL and ββXL) was measured in anesthetized rats after an intravenous bolus of 20 mg · 100 gm.^-1 To rule out the possibility that differences among plasma half times might be caused by differences in acute effects on renal excretory function, glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured simultaneously with plasma half time. Experiments were also done to determine whether higher doses (60 to 100 mg^-1 · 100 gm^-1) of these compounds had a delayed effect (48 hours) on GFR or ERPF. Massive urinary excretion of UHb occurred; however, only 1% of the ααXL and none of the ββXL was excreted. Plasma half time of ααXL and ββXL averaged 3.3 hours, or four times longer than UHb. In no case did a decrease in GFR or ERPF occur. Instead, a transient increase in GFR, ERPF, urine flow, and systemic blood pressure was seen. Similar increases occurred after albumin administration, suggesting expansion of vascular volume as the initiating factor. Renal functions at 48 hours after 60 to 100 mg · 100 gm^-1 of UHb, ααXL or ββXL were not different from control (albumin). Intratubular hemoglobin casts or intravascular precipitates were not evident in acute or 48-hour studies. At 48 hours Perls' staining material was found in one ααXL specimen at 3 hours after administration. Perls' staining material was present in renal tubule cells in all but the albumin-treated kidneys. In conclusion, differences in plasma half time are not caused by different effects on renal function. Lack of decreased renal function at 48 hours may be caused by the degree of purification of these preparations. Perls' staining material is present in tubule cells at 48 hours, whether unmodified or cross-linked hemoglobin had been given.