Cerebral blood flow and brain oxygenation in rats breathing oxygen under pressure.

Published

Journal Article

Hyperbaric oxygen (HBO(2)) increases oxygen tension (PO(2)) in blood but reduces blood flow by means of O(2)-induced vasoconstriction. Here we report the first quantitative evaluation of these opposing effects on tissue PO(2) in brain, using anesthetized rats exposed to HBO(2) at 2 to 6 atmospheres absolute (ATA). We assessed the contribution of regional cerebral blood flow (rCBF) to brain PO(2) as inspired PO(2) (PiO(2)) exceeds 1 ATA. We measured rCBF and local PO(2) simultaneously in striatum using collocated platinum electrodes. Cerebral blood flow was computed from H(2) clearance curves in vivo and PO(2) from electrodes calibrated in vitro, before and after insertion. Arterial PCO(2) was controlled, and body temperature, blood pressure, and EEG were monitored. Scatter plots of rCBF versus PO(2) were nonlinear (R(2)=0.75) for rats breathing room air but nearly linear (R(2)=0.88-0.91) for O(2) at 2 to 6 ATA. The contribution of rCBF to brain PO(2) was estimated at constant inspired PO(2), by increasing rCBF with acetazolamide (AZA) or decreasing it with N-nitro-L-arginine methyl ester (L-NAME). At basal rCBF (78 mL/100 g min), local PO(2) increased 7- to 33-fold at 2 to 6 ATA, compared with room air. A doubling of rCBF increased striatal PO(2) not quite two-fold in rats breathing room air but 13- to 64-fold in those breathing HBO(2) at 2 to 6 ATA. These findings support our hypothesis that HBO(2) increases PO(2) in brain in direct proportion to rCBF.

Full Text

Duke Authors

Cited Authors

  • Demchenko, IT; Luchakov, YI; Moskvin, AN; Gutsaeva, DR; Allen, BW; Thalmann, ED; Piantadosi, CA

Published Date

  • October 2005

Published In

Volume / Issue

  • 25 / 10

Start / End Page

  • 1288 - 1300

PubMed ID

  • 15789033

Pubmed Central ID

  • 15789033

International Standard Serial Number (ISSN)

  • 0271-678X

Digital Object Identifier (DOI)

  • 10.1038/sj.jcbfm.9600110

Language

  • eng

Conference Location

  • United States