DIFFERENT EFFECTS OF EICOSAPENTAENOIC ACID AND OLIVE OIL ON BLOOD-PRESSURE, INTRACELLULAR FREE PLATELET CALCIUM, AND PLASMA-LIPIDS IN PATIENTS WITH ESSENTIAL-HYPERTENSION

In a randomized, double-blind, cross-over study our specific aim was t o examine the effects of a dietary fish oil or olive oil supplementati on on blood pressure, intracellular free platelet calcium, plasma lipo proteins, and circulating vasoactive substances such as norepinephrine , epinephrine, and renin in patients with essential hypertension. Ten hypertensive patients (WHO classes I, II) were randomly assigned to re ceive 9 g fish oil or 9 g olive oil daily for 6 weeks after a 4-week b aseline period. The 6-week treatment periods were separated by a 4-wee k wash-out. During treatment with fish oil diastolic blood pressure de creased from 103 +/- 1 to 98 +/- 2 mmHg (P < 0.05) but did not change significantly during olive oil intake. Systolic blood pressure was not affected by either treatment. Intracellular free platelet calcium dec reased in patients receiving fish oil (from 102 +/- 8 nM to 86 +/- 6 n M, P < 0.05) but was not significantly altered by olive oil treatment. In contrast, the dose-response curve for thrombin-induced intracellul ar free platelet calcium was not altered by the fish oil enriched diet . Plasma triglycerides decreased by approximately 40% in the fish oil group while low-density lipoprotein cholesterol, high-density lipoprot ein cholesterol, and total cholesterol were not altered. Renin activit y, norepinphrine, and epinephrine in plasma were not influenced by fis h oil supplementation. We conclude that a moderate increase in dietary fish oil reduces diastolic blood pressure, intracellular free platele t calcium, and plasma triglycerides in patients with essential hyperte nsion. The decrease in basal intracellular free platelet calcium conce ntration does not seem to be due to a diminished responsiveness bf the calcium messenger system to thrombin.