Vascular reactivity and high dietary eicosapentaenoic acid

Area of Science:

• Cardiovascular Science
• Nutritional Science
• Pharmacology

Background:

• Epidemiologic studies link high dietary eicosapentaenoic acid (EPA) intake to reduced myocardial infarction incidence.
• EPA is a precursor to trienoic prostaglandins, which influence vascular function.
• Vascular reactivity plays a critical role in cardiovascular health.

Purpose of the Study:

• To investigate the effect of dietary EPA supplementation on vascular reactivity in isolated rat aortic strips.
• To determine the role of intrinsic prostaglandins in mediating vascular responses to norepinephrine and arachidonate.
• To assess how EPA affects the augmentation of vascular contraction by prostaglandins.

Main Methods:

• Rats were fed either a control diet or a diet supplemented with menhaden fish oil (17% EPA) for 3 weeks.
• Vascular reactivity of isolated aortic strips was examined using various contractile agents: norepinephrine, sodium arachidonate, KCl, PGF2α, and nitroprusside.
• The effect of indomethacin, a prostaglandin synthesis inhibitor, on vascular responses was evaluated.

Main Results:

• Aortic strips from rats fed the EPA-rich fish oil diet showed significantly reduced responsiveness to norepinephrine and arachidonate.
• Indomethacin treatment decreased norepinephrine responsiveness, with a greater effect in control rats, normalizing responses between groups.
• Contractions induced by arachidonate were abolished by indomethacin, indicating prostaglandin mediation.
• No differences in responses to KCl, PGF2α, or nitroprusside were observed between the groups.
• Aortic strips from fish oil-fed rats had higher EPA content.

Conclusions:

• Dietary EPA intake diminishes the augmentation of norepinephrine-induced contraction by intrinsic prostaglandins in rat aortic strips.
• EPA's influence on prostaglandin synthesis may underlie its association with reduced myocardial infarction risk.
• These findings highlight a potential mechanism for the cardioprotective effects of omega-3 fatty acids.