title: Characterization of induced pulpal hypoxia using 3H-misonidazole.
abstract: Tritiated misonidazole (3H-MISO) is a bioreductively activated marker which preferentially binds to cells with decreased oxygen tension (hypoxia). Detection of hypoxia may be an important indicator of metabolic imbalance. For 3H-MISO to be functional as a marker, normal oxygen (normoxic) levels must be distinguishable from increased hypoxic retention. This investigation characterized retention of 3H-MISO in: (a) normoxic pulp, (b) induced hypoxic pulp, and (c) reoxygenated hypoxic pulp. Rats were injected intraperitoneally with either 3H-MISO, unlabeled MISO, or saline, then divided into normoxic and hypoxic groups with appropriate controls. Normoxic animals were maintained at ambient pressure. Hypoxia was induced by placing animals in a hypobaric chamber at 0.5 atm. Pulps were then removed and prepared for liquid scintillation counting. Hypoxic pulps retained significantly more 3H-MISO than normoxic pulps (analysis of variance, p = 0.001). Hypoxic 3H-MISO retention was unaffected by subsequent, transient tissue reoxygenation. 3H-MISO detects changes in pulpal oxygen status that deviate from normal.
authors.affiliation: Department of Endodontics, University of Iowa, Iowa City 52246, USA.
authors.forename: K R
authors.initials: KR
authors.lastname: Baumgardner
authors.forename: J W
authors.initials: JW
authors.lastname: Osborne
authors.forename: R E
authors.initials: RE
authors.lastname: Walton
authors.forename: J L
authors.initials: JL
authors.lastname: Born
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D015687:Cell Hypoxia / Q000502:physiology; D003788:Dental Pulp Diseases / Q000175:diagnosis / Q000378:metabolism*; D006931:Hyperbaric Oxygenation; D000860:Hypoxia / Q000175:diagnosis; D008297:Male; D008920:Misonidazole / Q000493:pharmacokinetics; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley; D014316:Tritium
chemical_list: D014316:Tritium; D008920:Misonidazole