Ultrapure Polymerized Bovine Hemoglobin Improves Structural and Functional Integrity of the Isolated Perfused Rat Kidney

Abstract

Since it became evident that organ dysfunctions after acute hemolysis are not induced by hemoglobin per se, but by stroma-contaminated hemoglobin, solutions of ultrapure stroma-free hemoglobins were regarded to be possible substitutes for blood in transfusion medicine. We tested one of the recently developed modified bovine hemoglobins (Ultrapure polymerized bovine hemoglobin 1; UPPBHb1) in the isolated perfused rat kidney (IPRK) model, using a recirculating system. Control kidneys were perfused with a substrate-enriched Ringer solution containing hydroxyethyl starch (HES) to produce isoncotic conditions. In the experimental group HES was substituted in part by UPPBHb1 (34 g/l). For determination of functional parameters, the kidneys were perfused for 180 min. A separate set of kidneys of both groups was perfusion fixed after 80 min of perfusion which is the period of optimal function. Light and electron microscopic analysis revealed major alterations only for the outer medulla of HES kidneys. Only these suffered from a considerable extent of proximal tubular S3 damage, exhibiting condensed tubular epithelia. In the inner stripe of the outer medulla, which is the zone of greatest sensitivity to damage in the isolated perfused kidney, severe hydropic degeneration, cell detachment, and necrotic destruction of the medullary thick ascending limb were seen in the HES-perfused group, too. In the UPPBHb1 group, the medullary thick ascending limb was well preserved, and S3 showed only a minor degree of damage. UPPBHB1 kidneys were further characterized by the occurrence of intracapillary and interstitial precipitates of UPPBHb1 in inner stripe of the outer medulla and inner medulla. The glomerular filtration rate was significantly higher in UPPBHb1-perfused kidneys (870 ± 80 vs. 630 ± 55 µl/min/g kidney weight for HES). Absolute reabsorption of sodium paralleled the behavior of the glomerular filtration rate. The values for renal perfusate flow and urinary flow rate did not differ significantly between both groups. Renal autoregulation was better preserved in UPPBHb1-perfused kidneys (74 ± 6% of full autoregulatory response) than in HES-perfused controls (42 ± 4%). Our results suggest that perfusion of isolated rat kidneys with UPPBHb1 improves kidney function and morphology, providing better oxygenation than in control kidneys. UPPBHb1 does not exert additional nephrotoxic effects on the IPRK that will exceed the noxious potential of the method itself. Thus, it must be concluded that UPPBHb1 may be an oxyphoretic blood substitute with nephroprotective characteristics when compared with nonoxyphoretic substitutes. At least, UPPBHb1 seems to be a promising candidate as oxyphoretic additive to perfusates for the IPRK model.

Effects of Ultra-Purified Polymerized Bovine Hemoglobin on Local Tissue Oxygen Tension in Striated Skin Muscle – An Efficacy Study in the Hamster

“…This is consistent with findings of raised tissue oxygenation yielding improved organ function and morphology, when U-PBHb was compared to an iso-oncotic perfusion fluid in rat kidneys [36].…”

Effect of purified Russell’s viper venom-factor X activator (RVV-X) on renal hemodynamics, renal functions, and coagulopathy in rats

“…Acute renal failure (ARF) is the main cause of death after an RV bite (Shastry et al, 1977; Sitprija and Boonpucknavig, 1977; Mahasandana et al, 1980; Than et al, 1989; Thein et al, 1991; Tin Nu et al, 1993). Several studies have demonstrated that the pathogenesis of ARF is related to intravascular hemolysis, hypotension, hypovolemia, DIC, and also direct nephrotoxicity of the venom (Chugh et al, 1984; Ratcliffe et al, 1989; Than et al, 1989; Thamaree et al, 1994; Willinger et al, 1995). However, the exact pathogenesis of ARF following D. r. siamensis envenoming is not well established.…”

Kidney preservation in the next millenium

“…Support for this interpretation was provided by the findings of Tam and Wong [98], showing that polymerization of hemoglobin into very large macromolecules prevented passage through the glomerular filter. In a study performed by Willinger et al [108], ultrapure polymerized bovine hemoglobin was used to evaluate the structural and functional integrity of isolated perfused rat kidneys. They demonstrated a beneficial effect of the polymerized hemoglobin on kidney function, morphology, and oxygenation in comparison to control kidneys perfused with a hydroxylethyl starch solution.…”