title: Nail fold capillary diameter changes in acute systemic hypoxia.
abstract: The present study was undertaken to determine the effect of arterial blood hypoxemia induced by acute systemic hypoxia (pO2=12%) on capillary recruitment and diameter, and red blood cell (RBC) velocity in human nail fold capillaries during rest, arterial post-occlusive reactive hyperemia (PRH), and venous occlusion (VO) using intravital video-capillaroscopy. Capillary recruitment was unchanged in acute systemic hypoxia (H) versus normoxia (N). There was no difference in RBC velocity measurements between normoxia and hypoxia (P<0.63). However, a statistically significant increase in nail fold capillary total width (N, 39.9±9.1 vs. H, 42.7±10.3 μm; P<0.05), apical diameter (N, 15.5±4.3 vs. H, 16.8±4.3 μm; P<0.05), arterial diameter (N, 11.9±3.5 vs. H, 13.9±4.1 μm; P<0.05), and venous diameter (N, 15.5±4.3 vs. H, 17.2±4.8 μm; P<0.05) was observed and continued to be significant most often during post-occlusive reactive hyperemia (PRH) and venous congestion (VO). These data suggest that acute systemic hypoxia does not increase capillary recruitment, but instead increases capillary diameter, resulting in increased capillary blood flow.
authors.affiliation: University of Latvia Faculty of Biology, Department of Human and Animal Physiology, Latvia; University of Latvia Institute of Experimental and Clinical Medicine, Latvia. Electronic address: arturs.paparde@lu.lv.
authors.forename: Artūrs
authors.initials: A
authors.lastname: Paparde
authors.affiliation: University of Latvia Faculty of Biology, Department of Human and Animal Physiology, Latvia.
authors.forename: Ketija
authors.initials: K
authors.lastname: Nēringa-Martinsone
authors.affiliation: University of Latvia Faculty of Biology, Department of Human and Animal Physiology, Latvia; University of Latvia Institute of Experimental and Clinical Medicine, Latvia.
authors.forename: Līga
authors.initials: L
authors.lastname: Plakane
authors.affiliation: University of Latvia Faculty of Biology, Department of Human and Animal Physiology, Latvia.
authors.forename: Juris Imants
authors.initials: JI
authors.lastname: Aivars
mesh_terms: D001783:Blood Flow Velocity; D002196:Capillaries / Q000503:physiopathology*; D004912:Erythrocytes / Q000502:physiology; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D008833:Microcirculation; D020678:Microscopic Angioscopy; D009262:Nails / Q000098:blood supply*; D012039:Regional Blood Flow; D014664:Vasodilation; D014741:Video Recording; D055815:Young Adult
keywords: Acute systemic hypoxia; Capillaroscopy; Capillary; Capillary diameter; Capillary recruitment; Hypoxemia; Microcirculation; Nail fold; Post-occlusive reactive hyperemia; Venous occlusion