Cardioprotective Effect of the Adaptive Phenomenon of Early Hypoxic Preconditioning and Its Pharmacological Imitation.

The roles of NO synthase and ATP-dependent K⁺ channels (K_ATP channels) in the development of the infarct-limiting effect of early hypoxic preconditioning (HP) in rats were studied and the potential for pharmacological simulation of this phenomenon was demonstrated. HP was modeled by alternation of six 10-min sessions of normobaric hypoxia (8% O₂) and six 10-min periods of reoxygenation with atmospheric oxygen (21% O₂). The total duration of the adaptive action was 120 min. These results indicate that NO synthase and K_ATP channels play the role of mediators in the signal mechanism of HP. NO donors and K_ATP channel activators allow the protective effect of hypoxic preconditioning to be reproduced by administration 1 h before ischemia/reperfusion but not when given 2 h 30 min before coronary occlusion. [ABSTRACT FROM AUTHOR]