ANTIHYPERTENSIVE EFFECT OF ALL-CIS-5,8,11,14,17-ICOSAPENTAENOATE OF AGED RATS IS ASSOCIATED WITH AN INCREASE IN THE RELEASE OF ATP FROM THECAUDAL ARTERY

Fish oils have been shown to lower blood pressure in hypertensive subj ects. All-cis-5,8,11,14,17-icosapentaenoate (EPA), one of the omega-3 polyunsaturated fatty acids, is known to be one of the major active co mponents in fish oil that has beneficial effects on the cardiovascular system. However, little is known about the antihypertensive effect of EPA alone on blood pressure. In the present study, we have determined the spontaneous and noradrenaline-evoked release of ATP, ADP, AMP, an d adenosine from caudal arteries of aged (100 weeks old) Wistar rats w hich were fed a standard diet or a high cholesterol diet, treated with EPA. Dietary EPA administration increased plasma and caudal arterial EPA concentrations and repressed increases in blood pressure with adva ncing age in both aged rats with and without hypercholesterolemia. In addition, noradrenaline (1 mu mol/l) evoked a significantly greater re lease of purines from the caudal arteries of EPA-administered aged rat s compared to both sets of control rats. Regression analysis revealed a significant relationship between the total amount of purines release d from the artery and blood pressure. These results suggest that admin istration of EPA to aged rats increases the release of ATP from the va scular endothelial cells, leading to repression of the blood pressure rise seen with advancing age.