title: Sublingual microvascular perfusion is altered during normobaric and hyperbaric hyperoxia.
abstract: Hyperoxia and hyperbaric oxygen therapy can restore oxygen tensions in tissues distressed by ischemic injury and poor vascularization and is believed to also yield angiogenesis and regulate tissue perfusion. The aim of this study was to develop a model in which hyperoxia-driven microvascular changes could be quantified and to test the hypothesis that microcirculatory responses to both normobaric (NB) and hyperbaric (HB) hyperoxic maneuvers are reversible. Sublingual mucosa microcirculation vessel density, proportion of perfused vessels, vessel diameters, microvascular flow index, macrohemodynamic, and blood gas parameters were examined in male rabbits breathing sequential O2/air mixtures of 21%, 55%, 100%, and return to 21% during NB (1.0 bar) and HB (2.5 bar) conditions. The results indicate that NB hyperoxia (55% and 100%) produced significant decreases in microvascular density and vascular diameters (p<0.01 and p<0.05, respectively) accompanied by significant increases in systolic and mean arterial blood pressure (p<0.05, respectively) with no changes in blood flow indices when compared to NB normoxia. HB normoxia/hyperoxia resulted in significant decreases in microvascular density (p<0.05), a transient rise in systolic blood pressure at 55% (p<0.01), and no changes in blood vessel diameter and blood flow indices when compared to NB hyperoxia. All microcirculation parameters reverted back to normal values upon return to NB normoxia. We conclude that NB/HB hyperoxia-driven changes elicit reversible physiological control of sublingual mucosa blood perfusion in the presence of steady cardiovascular function and that the absence of microvascular vasoconstriction during HB conditions suggests a beneficial mechanism associated with maintaining peak tissue perfusion states.
authors: Department of Oral & Maxillofacial Surgery, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands. Electronic address: D.M.Milstein@amc.uva.nl.
authors: Dan M J
authors: DM
authors: Milstein
authors: Department of Oral & Maxillofacial Surgery, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands.
authors: Renée
authors: R
authors: Helmers
authors: Department of Large Laboratory Animals, Animal Research Institute Academic Medical Center (ARIA), University of Amsterdam, Meibergdreef 31, 1105 AZ, The Netherlands.
authors: Sanne
authors: S
authors: Hackmann
authors: Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands.
authors: Charly N W
authors: CN
authors: Belterman
authors: Department of Hyperbaric Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands; Diving Medical Center, Royal Netherlands Navy, PO Box 10000, 1780 CA Den Helder, The Netherlands; Laboratory of Experimental Intensive Care and Anesthesiology (LEICA), Department of Anesthesiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands.
authors: Robert A
authors: RA
authors: van Hulst
authors: Department of Oral & Maxillofacial Surgery, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands.
authors: Jan
authors: J
authors: de Lange
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D004195:Disease Models, Animal; D006931:Hyperbaric Oxygenation; D018496:Hyperoxia / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008833:Microcirculation; D018715:Microscopy, Video; D055806:Microvessels / Q000503:physiopathology*; D009060:Mouth Floor / Q000098:blood supply*; D009061:Mouth Mucosa / Q000098:blood supply*; D011817:Rabbits; D012039:Regional Blood Flow; D013997:Time Factors; D014661:Vasoconstriction
keywords: Animal model; Hyperbaric; Hyperoxia; Intrabarochamber; Microcirculation; Mucosa; Normobaric; Oxygen