Acute hyperglycemia abolishes cardioprotection by remote ischemic perconditioning

Area of Science:

• Cardiovascular Research
• Metabolic Syndrome
• Ischemic Heart Disease

Background:

• Remote ischemic perconditioning (RIPerC) shows therapeutic potential for acute myocardial infarction.
• Chronic conditions like diabetes can interfere with conditioning interventions by altering signaling pathways.
• The impact of acute hyperglycemia on RIPerC remains uninvestigated.

Purpose of the Study:

• To investigate the effect of acute hyperglycemia on the cardioprotective efficacy of RIPerC.
• To explore the underlying molecular mechanisms, including mTOR pathway and autophagy.
• To assess the role of nitrative stress in modulating RIPerC's effects.

Main Methods:

• Wistar rats were divided into normoglycemic and acute hyperglycemic groups.
• Acute hyperglycemia was induced via glucose infusion (15-20 mM serum glucose).
• Both groups underwent reversible coronary artery occlusion with or without RIPerC, followed by infarct size measurement and molecular analysis.

Main Results:

• RIPerC significantly reduced infarct size in normoglycemic rats but not in hyperglycemic rats.
• Acute hyperglycemia increased arrhythmia incidence and duration.
• Hyperglycemia activated the mTOR pathway, increased nitrative stress, and altered autophagy markers.

Conclusions:

• Acute hyperglycemia significantly deteriorates the cardioprotection offered by RIPerC.
• The observed impairment is likely mediated by increased nitrative stress and mTOR pathway activation.
• These findings highlight the importance of glycemic control in cardiac protection strategies.