Acute and chronic effects of eicosapentaenoic acid (EPA) on the cardiovascular system

Several studies have shown that the development of high blood pressure in spontaneously hypertensive rats (SHR) can be attenuated by feeding them modified fat diets. In the present study, eight weeks after treatment with eicosapentaenoic acid (EPA; 100 mg/kg/day s.c.) SHR had lower systolic blood pressure (BP); (tail-cuff plethysmography) compared to saline-injected SHR: 180.0 +/- 2 vs. 204.0 +/- 1 mmHg, respectively, (p less than 0.001). There was no significant difference in the BP of EPA and saline-treated WKY (Wistar-Kyoto) rats. Heart rate (HR) decreased with age in both the SHR and WKY rats and no significant effect of EPA was observed in WKY rats; the decrease in heart rate in the SHR group was significantly diminished. EPA did not significantly alter growth rate of SHR and WKY rats. However, aged-matched WKY rats weighed more than the SHR. The pressor responses to norepinephrine in doses of 0.3 and 3.0 microgram/kg, i.v., as well as plasma NE, DOPA and MHPG, were also not significantly affected by EPA-supplementation in both SHR and WKY rats. Data from the present study support the view that EPA might be an effective treatment of hypertension that develops via mechanisms unrelated to sympathetic activity or vascular reactivity to adrenergic neurotransmitters.