Hemoglobin-based
oxygen carriers (HBOC) have been primarily studied for blood loss treatment. More recently infusions of HBOC in euvolemic subjects have been proposed for a wide variety of potential
therapies in which increased tissue oxygenation would be beneficial. However, compared with the exchange transfusion models to study blood loss, less is known about HBOC
oxygen delivery and vasoacitvity when it is infused in euvolemic subjects. We hypothesized that HBOC [
polymerized bovine hemoglobin (PBvHb)] infusion creating hypervolemia would increase
oxygen delivery to tissues during acute global
hypoxia. Vascular
oxygen content and hemodynamics were determined after euvolemic rats were infused with 3 ml of either lactated Ringer or PBvHb
solution (13 g/dl, 1.3 g/kg) during acute
hypoxia (FIO2 = 10%, 4 h) or normoxia (FIO2 = 21%) exposure. Our data demonstrated that compared with Ringer-infused animals, in
hypoxia and normoxia, PBvHb treatment improved
oxygen content but raised mean arterial pressure, lowered stroke volume, heart rate, and cardiac index, which resulted in a net reduction in blood flow and
oxygen delivery to the tissues. The PBvHb vasoactive effect was similar in magnitude and direction as to the Ringer-infused animals treated with a
nitric oxide synthase inhibitor nitro-
l-arginine, suggesting the PBvHb effect is mediated via
nitric oxide scavenging. We conclude that infusion of PBvHb is not likely to be useful in treating global
hypoxia under these conditions.