Polymerized bovine hemoglobin decreases oxygen delivery during normoxia and acute hypoxia in the rat.
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.
Cardiovascular Pulmonary Research Group, School of Medicine, University of Colorado Health Science Center, 4200 E 9Ave., Denver, CO 80262, USA. David.irwin@UCHSC.edu
David C
DC
Irwin
Ben
B
Foreman
Ken
K
Morris
Molly
M
White
Tim
T
Sullivan
Robert
R
Jacobs
Eric
E
Monnet
Tim
T
Hackett
Martha C
MC
TissotvanPatot
Karyn L
KL
Hamilton
Robert W
RW
Gotshall
D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D001802:Blood Substitutes / Q000494:pharmacology*; D002302:Cardiac Output / Q000187:drug effects; D002417:Cattle; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D000860:Hypoxia / Q000097:blood*; D008297:Male; D008706:Methemoglobin / Q000032:analysis; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects*; D011652:Pulmonary Circulation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013318:Stroke Volume / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects
D001802:Blood Substitutes; D004791:Enzyme Inhibitors; D008706:Methemoglobin; D019001:Nitric Oxide Synthase; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester