Nitric Oxide Scavenging, HBOC Vasoconstriction & Tissue Oxygenation
Why oxygen-carrying capacity alone does not define effective oxygen delivery.
1. The Study
Article: Zhang R, Hess DT, Qian Z, et al.
Hemoglobin βCys93 is essential for cardiovascular function and integrated response to hypoxia. PNAS. 2015;112(20):6425-6430.
PubMedPMID 25810253
DOI10.1073/pnas.1502285112
2. Key Finding
The study examined mice in which hemoglobin βCys93 was replaced by alanine. Hemoglobin could still carry oxygen, but hypoxic vasodilation, peripheral blood flow and tissue oxygenation were impaired.
Key point: oxygen content in blood is not enough. Tissue oxygenation also depends on how blood flow is regulated when local oxygen demand changes.
3. Why This Is Important
Hemoglobin is part of a larger oxygen-delivery system. The physiological endpoint is not simply how much O₂ is bound to hemoglobin, but whether oxygen reaches tissue through an adequately regulated microcirculation.
This connects three functions that should be evaluated together: oxygen carriage → vascular response → tissue oxygenation.
4. Relevance to HBOC and BHOC
Cell-free hemoglobin interacts with nitric oxide differently from hemoglobin enclosed inside red blood cells. In the HBOC literature, nitric oxide scavenging is a major mechanism associated with vasoconstriction, increased vascular resistance and altered perfusion.
For BHOC development, the practical question is therefore not only “How much oxygen can the carrier transport?” but also “What happens to vascular tone, microcirculatory flow and oxygen unloading after administration?”
BHOC significance: an effective oxygen carrier should be judged by functional tissue oxygen delivery, not hemoglobin concentration alone. NO interaction, vasoconstriction/vasodilation, oxygen affinity, molecular size and microcirculatory behavior belong in the same evaluation framework.
5. Supporting References
Zhang R, et al. 2015. Hemoglobin βCys93 is essential for cardiovascular function and integrated response to hypoxia.
PubMed ↗ ·
DOI ↗
Allen BW, Stamler JS, Piantadosi CA. 2009. Hemoglobin, nitric oxide and molecular mechanisms of hypoxic vasodilation.
PubMed ↗ ·
DOI ↗
Taverne YJ, et al. 2017. Normalization of hemoglobin-based oxygen carrier-201 induced vasoconstriction: targeting nitric oxide and endothelin.
PubMed ↗ ·
DOI ↗
1998 Nobel foundation: Nitric Oxide & Vascular Physiology →
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