Low Oxygen Affinity Hemoglobin HBOC‐201 enables increased Oxygen Uptake (VO2) In Bovine Pulmonary Artery Endothelial Cells (BPAEC)

Hemoglobin‐based oxygen carriers (HBOCs) with various oxygen affinities are currently being evaluated for clinical use. We tested whether HBOCs with high vs. low oxygen affinities can affect cellular oxygen uptake (VO 2 ), using a BPAEC model. Methods: Confluent BPAECs, passages 3–6, were maintained in RPMI media, supplemented with 10% FBS, L‐glutamine, and antibiotics. 5 ×10 7 cells, were placed in a respirometer, containing 100μl of room air saturated buffer in the absence or presence of 1.35 g/dl HBOC‐201® (p50=26 torr @ 21.5ºC) or 1.35 g/dl HbA 0 (p50= 6.9 @ 21.5ºC). Uncoupling 0.3μM carbonyl cyanide 4(tri‐fluoromethoxy) phenylhyrdrazone (FCCP) was used to trigger maximal mitochondrial VO 2 . The HBOC‘s oxygen dissociation curves were corrected for pH and temperature (J Appl Physiol. 94(2):561–6.2003). VO 2 was defined as use of (free + bound) O 2 divided by the time to full O 2 depletion. Results: Untreated BPAECs had a VO 2 of 3.09 ± 3.9 nmoles O 2 /min, which increased to 7.34 ± 5.1 with FCCP. The VO 2 of BPAECs treated with HBOC‐201 was 6.69 ± 2.5 nmoles O 2 /min, which increased to 10.43 ± 9.1 with uncoupler. When 2,3‐DPG‐free human HbA 0 was combined with FCCP the VO 2 was 4.41 ± 2.3 nmoles O 2 /min, higher than basal control VO 2 but lower than that in presence of HBOC‐201 + FCCP. Conclusion: Low oxygen affinity HBOC‐201 facilitates VO 2 by BPAECS relative to high oxygen affinity HBOC preparations such as human HbA 0 .