Effect of pure eicosapentaenoic acid feeding on blood pressure and vascular reactivity in spontaneously hypertensive rats.

1. This study examined the effects of eicosapentaenoic acid (EPA) treatment on vascular reactivity and blood pressure in spontaneously hypertensive rats (SHR). 2. Twenty SHR were given pure EPA as the methyl ester (280 mg/kg) by gavage for 10 days. An equal number of control rats received vehicle alone. EPA treatment had no effect on blood pressure compared with control rats. 3. Aortic rings from EPA-treated rats, precontracted with PGF2 alpha showed increased endothelium-dependent relaxations to acetylcholine. Endothelium-independent relaxations to sodium nitroprusside were not altered. Rings from rats fed pure EPA did not show any differences in vasoconstrictor responses to noradrenaline or serotonin. 4. Serum thromboxane B2 (TXB2) levels fell 17% in animals given pure EPA, but prostacyclin production was not affected. These responses are less than those seen following Max EPA fish oil. 5. Thus, pure EPA treatment did not lower blood pressure, but may have a direct effect on aortic endothelia and cause increased endothelium-dependent relaxations in response to acetylcholine in SHR.