Purpose: Delayed volatile anesthetic preconditioning (APC) can protect against myocardial ischemia/reperfusion (I/R) injury; the delayed phase is called the second window of protection (SWOP), but the underlying mechanism is unclear. Nuclear factor-κB (NF-κB) is involved in the myocardial protection conferred by APC in the acute phase; autophagy has been reported to confer apoptosis inhibition and infarction reduction. We hypothesized that APC initiates delayed cardioprotection against I/R injury via the activation of NF-kB and upregulation of autophagy, thus attenuating the inflammatory response and apoptosis
Methods: After a rat I/R model was set up, left ventricular samples were obtained before I/R to assess NF-κB-DNA binding activity and microtubule-associated protein 1 light chain 3 (LC3) and cathepsin B protein expression, and to examine autophagosomes with a transmission electron microscope. Infarct size and the expressions of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and caspase-3 were measured at the end of 2-h reperfusion.
Results: The infarct size was significantly reduced in the SWOP group (30 ± 3 %) when compared with that in the I/R group (47 ± 7 %, P < 0.05), and this finding was associated with increased NF-κB-DNA binding activity and autophagosomes. In addition, the expressions of LC3-II and cathepsin B were also up-regulated, and the expressions of TNF-α, IL-1β, and caspase-3 were attenuated in the SWOP group when compared with the findings in the I/R group. However, this protection was abolished by the administration of parthenolide (PTN) before sevoflurane inhalation, which resulted in an infarct size that was significantly increased (47 ± 5 %, P < 0.05 PTN + SWOP vs. SWOP group).
Conclusion: Delayed APC protected the rat heart from I/R injury. The underlying mechanisms may include NF-κB activation, upregulation of autophagy, and the attenuation of TNF-α, IL-1β, and caspase-3 expressions.