Cardiac systolic and diastolic dysfunction after a cholesterol-rich diet

Area of Science:

• Cardiology
• Biochemistry
• Molecular Biology

Background:

• Hypercholesterolemia is a known risk factor for coronary artery disease.
• Direct effects of high cholesterol on cardiac function remain largely unknown.

Purpose of the Study:

• To investigate the direct impact of dietary hypercholesterolemia on cardiac function.
• To elucidate the molecular mechanisms underlying cholesterol-induced cardiac dysfunction.

Main Methods:

• Rabbits were fed a diet containing 0.5% cholesterol for 10 weeks.
• Cardiac function, including systolic shortening and diastolic relaxation, was assessed.
• Sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA)-2 mRNA and protein levels were measured.
• Myosin heavy chain (MHC) mRNA ratios and sarcolemmal cholesterol content were analyzed.

Main Results:

• Cholesterol feeding impaired both systolic shortening and diastolic relaxation rates.
• SERCA-2 mRNA levels decreased significantly within 4 days, followed by impaired protein function and reduced calcium uptake.
• The ratio of MHC-beta to MHC-alpha mRNA increased fivefold, indicating altered cardiac contractility.
• These cardiac changes correlated with increased cholesterol in the cardiac sarcolemma.

Conclusions:

• Dietary hypercholesterolemia induces a distinct cardiac dysfunction, termed "cholesterol cardiomyopathy."
• The observed systolic and diastolic dysfunction are direct consequences of high cholesterol, not secondary to vascular disease.
• This study establishes a direct dietary link to cardiac dysfunction, highlighting the heart's vulnerability to cholesterol overload.