Ischemic preconditioning and infarct mass: the effect of hypercholesterolemia and endothelial dysfunction

Area of Science:

• Cardiovascular Science
• Atherosclerosis Research
• Ischemic Heart Disease

Background:

• Hypercholesterolemia is a risk factor for cardiovascular disease.
• Endothelial dysfunction is an early sign of atherosclerosis.
• Ischemic preconditioning offers cardioprotection, but its efficacy in hypercholesterolemia is unclear.

Purpose of the Study:

• To investigate endothelial dysfunction in hypercholesterolemia.
• To determine the effect of hypercholesterolemia on infarct size.
• To assess if hypercholesterolemia affects the cardioprotective benefits of ischemic preconditioning.

Main Methods:

• Rabbits were fed either a normal or an atherogenic diet (high cholesterol and coconut oil) for four weeks.
• Myocardial ischemia was induced, followed by reperfusion to assess infarct mass.
• Ischemic preconditioning was applied before sustained ischemia in separate groups.
• Aortic endothelium-dependent function and nitric oxide (NO) release were measured.

Main Results:

• Hypercholesterolemic rabbits exhibited endothelial dysfunction and reduced NO release but no atherosclerotic lesions.
• Infarct mass was significantly increased in hypercholesterolemic rabbits compared to controls.
• Ischemic preconditioning reduced infarct mass in normal rabbits.
• Hypercholesterolemia did not diminish the infarct-reducing effect of ischemic preconditioning.

Conclusions:

• Experimental hypercholesterolemia causes endothelial dysfunction and increases infarct size.
• Ischemic preconditioning remains cardioprotective in the presence of hypercholesterolemia.
• The findings suggest that nitric oxide may not be the primary mediator of ischemic preconditioning's cardioprotective effects.