Hemoglobin α in the blood vessel wall.
Hemoglobin has been studied and well characterized in red blood cells for over 100 years. However, new work has indicated that the hemoglobin α subunit (Hbα) is also found within the blood vessel wall, where it appears to localize at the myoendothelial junction (MEJ) and plays a role in regulating nitric oxide (NO) signaling between endothelium and smooth muscle. This discovery has created a new paradigm for the control of endothelial nitric oxide synthase activity, nitric oxide diffusion, and, ultimately, vascular tone and blood pressure. This review discusses the current knowledge of hemoglobin׳s properties as a gas exchange molecule in the bloodstream and extrapolates the properties of Hbα biology to the MEJ signaling domain. Specifically, we propose that Hbα is present at the MEJ to regulate NO release and diffusion in a restricted physical space, which would have powerful implications for the regulation of blood flow in peripheral resistance arteries.
Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA.
Joshua T
JT
Butcher
Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA.
Tyler
T
Johnson
Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA.
Jody
J
Beers
Department of Chemistry, University of Virginia, Charlottesville, VA 22908, USA.
Linda
L
Columbus
Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA; Department of Molecular Physiology and Biophysics, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA. Electronic address: brant@virginia.edu.
Brant E
BE
Isakson
D001794:Blood Pressure / Q000502:physiology; D004730:Endothelium, Vascular / Q000502:physiology; D006454:Hemoglobins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009130:Muscle, Smooth / Q000098:blood supply* / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D011659:Pulmonary Gas Exchange; D012039:Regional Blood Flow / Q000502:physiology*; D014655:Vascular Resistance / Q000502:physiology*
D006454:Hemoglobins; D010446:Peptide Fragments; C070077:alpha(A) globin; D009569:Nitric Oxide; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III
Cytochrome b(5) reductase 3; Free radicals; Hemoglobin; Hemoglobin α; Myoendothelial junction; Nitric oxide; α-Thalassemia