Oxygen Measurements in Brain Stem Slices Exposed to Normobaric Hyperoxia and Hyperbaric OxygenJournal of Applied Physiology
AbstractWe previously reported (J Appl Physiol 89: 807–822, 2000) that ≤10 min of hyperbaric oxygen (HBO2; ≤2,468 Torr) stimulates solitary complex neurons. To better define the hyperoxic stimulus, we measured PO 2 in the solitary complex of 300-μm-thick rat medullary slices, using polarographic carbon fiber microelectrodes, during perfusion with media having PO 2 values ranging from 156 to 2,468 Torr. Under control conditions, slices equilibrated with 95% O2at barometric pressure of 1 atmospheres absolute had minimum PO 2 values at their centers (291 ± 20 Torr) that were ∼10-fold greater than PO 2values measured in the intact central nervous system (10–34 Torr). During HBO2, PO 2 increased at the center of the slice from 616 ± 16 to 1,517 ± 15 Torr. Tissue oxygen consumption tended to decrease at medium PO 2 ≥ 1,675 Torr to levels not different from values measured at PO 2 found in all media in metabolically poisoned slices (2-deoxy-D-glucose and antimycin A). We conclude that control medium used in most brain slice studies is hyperoxic at normobaric pressure. During HBO2, slice PO 2 increases to levels that appear to reduce metabolism.
Citation InformationDaniel K. Mulkey, Richard A. Henderson, James E. Olson, Robert W. Putnam, et al.. "Oxygen Measurements in Brain Stem Slices Exposed to Normobaric Hyperoxia and Hyperbaric Oxygen" Journal of Applied Physiology Vol. 90 Iss. 5 (2001) p. 1887 - 1899 ISSN: 1522-1601
Available at: http://works.bepress.com/robert_putnam/25/