Comparison of early microcirculatory and aortic changes in hypercholesterolemic rats

Area of Science:

• Cardiovascular Science
• Microcirculation Research
• Endothelial Function Studies

Background:

• Hypercholesterolemia is a major risk factor for cardiovascular diseases.
• Understanding its early effects on vascular function is crucial for developing preventative strategies.
• The cremaster muscle and aortic ring models offer insights into microvascular and macrovascular responses.

Purpose of the Study:

• To investigate the impact of hypercholesterolemia on microcirculatory and aortic ring function in rats.
• To compare the effects of short-term (3 weeks) and medium-term (5 weeks) hypercholesterolemia.
• To elucidate the role of endothelium-derived relaxing factor (EDRF) in hypercholesterolemia-induced vascular changes.

Main Methods:

• Male Sprague-Dawley rats were fed either a control or hypercholesterolemic diet (1% cholesterol, 0.5% cholic acid) for 3 or 5 weeks.
• Intravital microscopy was used to study microcirculatory changes in the cremaster muscle.
• Aortic ring segments were used to assess vascular responses to various stimuli.

Main Results:

• Hypercholesterolemia significantly reduced vasodilator responses to serotonin in arterioles after 3 and 5 weeks.
• Serotonin induced increased macromolecular leakage from venules after 3 weeks, but this effect lessened after 5 weeks.
• Acetylcholine-induced arteriolar dilation and aortic ring relaxation were attenuated by hypercholesterolemia, suggesting impaired EDRF-mediated responses.

Conclusions:

• Hypercholesterolemia rapidly impairs endothelium-dependent vasodilation and vascular permeability in microvessels.
• Early depression of EDRF-mediated responses occurs in both microvessels and the aorta.
• These findings highlight the detrimental early effects of hypercholesterolemia on vascular health.