title: Tissue oxygen tension and blood-flow changes in rat incisor pulp with graded systemic hyperoxia.
abstract: The role of oxygen in the regulation of the pulpal microcirculation is unknown. This investigation is aimed to measure tissue oxygen tension and blood-flow changes in the pulp of rat lower incisors during graded systemic hyperoxia, and to determine the response of the pulpal vasculature to various oxygen tensions. Twenty-four Sprague-Dawley rats were anaesthetized and artificially ventilated with the appropriate gas mixture. Recessed oxygen-sensitive microelectrodes were used to measure pulpal tissue oxygen tension via a small access cavity filled with saline on the labial surface of the incisor. A laser Doppler flowmeter was used to record pulpal blood-flow. Inspired oxygen was increased stepwise from 20 to 100% in 20% steps. Systemic blood-gas concentrations were measured at each step. Systemic arterial oxygen tension at 100% oxygen ventilation reached 481.2 +/- 30.7% of the baseline at 20% oxygen breathing (n=21). Pulpal tissue oxygen tension did not change significantly whereas pulpal blood-flow fell dose-dependently to 74.6 +/- 5.0% at 100% oxygen ventilation (n=21). Systemic hyperoxia, therefore, induces a significant reduction in pulpal blood-flow whereas pulpal tissue oxygen tension remains relatively stable, indicating an oxygen-dependent local regulatory mechanism.
authors.affiliation: School of Dentistry, The University of Western Australia, 179 Wellington Street, Perth, WA 6000, Australia. chrisyu@cyllene.uwa.edu.au
authors.forename: Christine Y
authors.initials: CY
authors.lastname: Yu
authors.forename: Nick M
authors.initials: NM
authors.lastname: Boyd
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Cringle
authors.forename: Valerie A
authors.initials: VA
authors.lastname: Alder
authors.forename: Dao Yi
authors.initials: DY
authors.lastname: Yu
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003782:Dental Pulp / Q000098:blood supply* / Q000378:metabolism; D018496:Hyperoxia / Q000378:metabolism / Q000503:physiopathology*; D007180:Incisor / Q000098:blood supply; D017736:Ion-Selective Electrodes; D017078:Laser-Doppler Flowmetry; D008839:Microelectrodes; D010100:Oxygen / Q000032:analysis / Q000378:metabolism*; D010313:Partial Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow
chemical_list: D010100:Oxygen