Exercise-induced oxidative stress in older adults as measured by antipyrine oxidation

Aging is associated with increased susceptibility to free radical-mediated tissue damage. Measuring exercise-induced oxidative stress, however, is a m ajor problem in free radical research, We used an exogenous marker (antipyr ine) to measure oxidative stress in older adults during submaximal exercise . Antipyrine pharmacokinetics is independent of blood flow to the liver. Fu rthermore, antipyrine reacts quickly with hydroxyl radicals (10(10)-10(11) L.mol(-1).s(-1)) to form para- and orthohydroxyantipyrine (o-APOH). o-APOH is not formed in man through the mono-oxygenase pathway of cytochrome P450, Thirty-four subjects (62 +/-1 years) orally ingested 10 mg antipyrine/kg b ody mass. One hour after ingestion subjects cycled 45 minutes at 50% maxima l power output. Exercise significantly increased the ratio of para-hydroxya ntipyrine (p-APOH) to native antipyrine in plasma (.0014 +/- .0001 v .0021 +/- .0002; P<.0001). Also, the ratio of o-APOH was significantly increased after exercise (.0014<plus/minus>.0001 v .0019 +/- .0002; P<.0001). Exercis e significantly increased plasma levels of plasma malondialdehyde (MDA) (.5 5<plus/minus>.07 v .92 +/- .21 mu mol/L; P<.01). In conclusion, in older ad ults, oxidative stress occurs during cycling at submaximal intensity as mea sured with free radical reaction products of antipyrine. Copyright (C) 2001 by W.B. Saunders Company.