Endothelial beta-globin is differentially expressed across mammalian species

Abstract

Globin proteins interact with endothelial nitric oxide synthase at the myoendothelial junctions of resistance arteries to regulate nitric oxide signaling between endothelium and smooth muscle. Human resistance arteries express both alpha and beta globin to form heterotetrameric hemoglobin (α2β2). To better understand the role of hemoglobin in human resistance arteries, we need to identify an animal model in which both alpha and beta globin are expressed in the resistance vasculature. To identify potential candidates, we used microscopy to survey a range of mammalian laboratory animals for hemoglobin in the artery wall. We isolated arteries (100-200 μm in diameter) from mesenteric tissue collected from human patients undergoing clinically-indicated surgery and from the following laboratory animals: mouse ( Mus musculus, C57BL/6 strain), rat ( Rattus norvegicus, CD strain), African thicket rat ( Grammomys surdaster), guinea pig ( Cavia porcellus), New Zealand white rabbit ( Oryctolagus cuniculus), Beagle dog ( Canis lupus familiaris), and cynomolgus macaque ( Macaca fascicularis) after they underwent euthanasia on approved animal study protocols. We leveraged the autofluorescence of heterotetrameric hemoglobin under multiphoton excitation to visualize hemoglobin in the wall of intact, unstained, paraformaldehyde-fixed artery segments. Autofluorescent puncta representing tetrameric hemoglobin were observed in the wall of resistance arteries from the human patients, non-human primate, and canines, but not from rabbit nor any of the rodent species. The ability of beta globin to restrict endothelial NO signaling was confirmed in canine arteries ex vivo by testing a beta globin mimetic peptide that inhibited vasoconstriction to phenylephrine. In conclusion, primates and canines appear to have tetrameric hemoglobin in the resistance artery wall, whereas rodents and rabbits do not. This study highlights differences in vascular globin expression between humans and rodents and extends the recent discovery of hemoglobin in resistance arteries of humans to two additional mammalian species that may serve as models for studying the unique activities of tetrameric hemoglobin in the resistance vasculature. Funding: Intramural Research program, NIAID, NIH This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.