Neutrophil inhibition contributes to cardioprotection by postconditioning

Area of Science:

• Cardiovascular Science
• Myocardial Infarction Research
• Inflammation and Immunity

Background:

• Postconditioning is known to reduce myocardial infarct size, superoxide generation, and neutrophil accumulation.
• The specific role of neutrophils (PMNs) in mediating the cardioprotective effects of postconditioning remains unclear.

Purpose of the Study:

• To investigate whether inhibiting PMNs affects myocardial salvage achieved by postconditioning.
• To determine if postconditioning directly inhibits PMN superoxide generation.

Main Methods:

• Rats subjected to myocardial ischemia-reperfusion were studied with and without PMN depletion, with or without postconditioning, to assess infarct size.
• Canine models were used to sample blood from the anterior interventricular vein (AIV) to measure PMN superoxide generation after postconditioning.

Main Results:

• Both postconditioning and PMN depletion independently reduced infarct size in rats.
• Combining postconditioning with PMN depletion did not result in further significant reduction of infarct size compared to postconditioning alone.
• Postconditioning significantly reduced PMN accumulation in the area at risk and decreased PMN superoxide generation in dogs.

Conclusions:

• Neutrophil (PMN) involvement is implied in the cardioprotective mechanisms of postconditioning.
• Inhibition of PMNs may enhance or be a key component of postconditioning-mediated cardioprotection.