Breath ethane as a marker of reactive oxygen species during manipulation of diet and oxygen tension in rats

Breath ethane, O₂consumption, and CO₂ productionwere analyzed in 24-mo-old female Fischer 344 rats that had been fedcontinuously ad libitum (AL) or restricted 30% of AL level (DR) dietssince 6 wk of age. Rats were placed in a glass chamber that was first flushed with air, then with a gas mixture containing 12%O₂. After equilibration, a sampleof the outflow was collected in gas sampling bags for subsequentanalyses of ethane and CO₂. TheO₂ andCO₂ levels were also directlymonitored in the outflow of the chamber. O₂ consumption andCO₂ production increased for DRrats. Hypoxia decreased O₂consumption and CO₂ production forthe AL-fed and DR rats. These changes reflect changes in metabolic ratedue to diet and PO₂. A significantdecrease in ethane generation was found in DR rats compared with AL-fedrats. Under normoxic conditions, breath ethane decreased from 2.20 to1.61 pmol ethane/ml CO₂. Duringhypoxia the levels of ethane generation increased, resulting in aDR-associated decrease in ethane from 2.60 to 1.90 pmol ethane/mlCO₂. These results support thehypothesis that DR reduces the level of oxidative stress.