Effectiveness of a purified human hemoglobin as a blood substitute in the perfused rat liver

Abstract

The efficacy of purified cross-linked human hemoglobin solution in maintaining the metabolic integrity of perfused livers from fed rats was determined and compared with that of livers recirculated with red blood cells, perfluorocarbon, and Krebs' Ringer bicarbonate buffer media at normal and accelerated flow rates. The data indicate that oxygen utilization was comparable in livers perfused with red blood cell medium (53.5 ± 4.0 μL · g liver−1 · min−1), hemoglobin (45.7 ± 1.9), and perfluorocarbon (57.2 ± 6.1) and less in livers perfused with Krebs' Ringer bicarbonate buffer solution at normal (17.4 ± 1.4) and high (27.7 ± 1.4) flow rates. Bile flow, the outflow of glucose and lactic acid, and residual glycogen levels were similar when livers were perfused with red blood cells (hematocrit, 19) and hemoglobin solutions containing 7 g hemoglobin/dL at flow rates of 1.1–1.2 mL · g liver−1 · min−1. However, livers perfused with perfluorocarbon at 1.1 mL · g−1 · min−1 showed a significantly greater (P < 0.01) decline in bile flow and outflow of glucose and lactic acid. Livers perfused with Krebs' Ringer bicarbonate buffer at normal (1.3 mL · g−1 · min−1) and accelerated flow rates (3.0 mL · g−1 · min−1) also showed a progressive decrease in bile flow and marked glycogenolysis as well as depletion of adenosine triphosphate content. In addition, morphological studies (light and electron microscopy) showed more vacuoles, membrane alterations, and increased mitochondrial swelling in livers perfused with Krebs' Ringer bicarbonate buffer and perfluorocarbon. These findings suggest that hepatocyte function in livers from fed rats is maintained equally well with hemoglobin solutions and with red blood cell medium, suggesting that crosslinked hemoglobin solution may serve as an effective blood substitute for maintaining adequate oxygenation and metabolic integrity of the isolated perfused rat liver.