['We examined the role of reactive oxygen species (ROS) in sevoflurane- and desflurane-induced preconditioning on isolated human right atrial myocardium.', "We recorded isometric contraction of human right atrial trabeculae suspended in an oxygenated Tyrode's solution (34 degrees C, stimulation frequency 1 Hz). In all groups, a 30-min hypoxic period was followed by 60 min of reoxygenation. Ten minutes before hypoxia reoxygenation, muscles were exposed to 5 min of sevoflurane 2% or desflurane 6%. In separate groups, the sevoflurane 2% (Sevo + N-(2-mercaptopropionyl)-glycine [MPG]) or desflurane 6% (Des + MPG) was administered in the presence of 0.1 mM MPG, a ROS scavenger. The effect of 0.1 mM MPG alone was tested. Recovery of force after a 60-min reoxygenation period was compared between groups (mean +/- sd).", 'Preconditioning with sevoflurane 2% (85% +/- 4% of baseline) or desflurane 6% (86% +/- 7% of baseline) enhanced the recovery of the force of myocardial contraction after 60 min reoxygenation compared with the control group (53% +/- 11% of baseline, P < 0.001). This effect was abolished in the presence of MPG (56% +/- 12% of baseline for Sevo + MPG, 48% +/- 13% of baseline for Des + MPG). The effect of MPG alone on the recovery of force was not different from the control group (57% +/- 7% of baseline versus 53% +/- 11%; P = NS).'] Do reactive oxygen species mediate sevoflurane- and desflurane-induced preconditioning in isolated human right atria in vitro?