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

Breath ethane, O-2 consumption, and CO2 production were analyzed in 24-mo-o ld female Fischer 344 rats that had been fed continuously ad libitum (AL) o r restricted 30% of AL level (DR) diets since 6 wk of age. Rats were placed in a glass chamber that was first flushed with air, then with a gas mixtur e containing 12% O-2. After equilibration, a sample of the outflow was coll ected in gas sampling bags for subsequent analyses of ethane and CO2. The O a and CO2 levels were also directly monitored in the outflow of the chamber . O-2 consumption and CO2 production increased for DR rats. Hypoxia decreas ed O-2 consumption and CO2 production for the AL-fed and DR rats. These cha nges reflect changes in metabolic rate due to diet and Pot. A significant d ecrease in ethane generation was found in DR rats compared with AL-fed rats . Under normoxic conditions, breath ethane decreased from 2.20 to 1.61 pmol ethane/ml CO2. During hypoxia the levels of ethane generation increased, r esulting in a DR-associated decrease in ethane from 2.60 to 1.90 pmol ethan e/ml CO2. These results support the hypothesis that DR reduces the level of oxidative stress.