Effects of n-3 fatty acids in essential hypertension.

We examined the effects on blood pressure, plasma lipoproteins, and platelet function when marine oil supplements (rich in n-3 fatty acids) or vegetable oil supplements (rich in n-6 fatty acids) were added to the usual diets of patients with mild essential hypertension. In a randomized, double-blind, parallel-group study, patients received 50 g of either marine oil (n = 8) or vegetable oil (n = 8) daily for 6 weeks following a baseline observation period. Diastolic blood pressure declined during treatment with fish oil (mean +/- SEM, 96 +/- 2 v 89 +/- 2 mm Hg, P = .02), but did not change with vegetable oil (92 +/- 1 v 94 +/- 1 mm Hg). Systolic blood pressure did not change significantly during either treatment. Serum triglycerides declined (by approximately 30%) in patients receiving only marine oil, but total cholesterol, LDL-, HDL-, HDL2-, and HDL3-cholesterol-subfractions and apolipoproteins A-I and B were unchanged in both treatment groups. Bleeding time increased by 33% during treatment with marine oil but did not change with vegetable oil supplements. Marine oil did not alter in vitro platelet aggregation thresholds. The lack of a significant correlation between blood pressure changes and platelet membrane fluidity, plasma renin activity, aldosterone, norepinephrine, or epinephrine suggests that these variables did not mediate the antihypertensive effect of the marine oil. We conclude that large doses of marine oil reduce diastolic blood pressure, lower triglycerides, and increase bleeding time in patients with mild hypertension.

Hormone and catecholamine responses accompanying the antinatriuresis of glucose ingestion.

The purpose of this study was to determine the importance of various neurohormonal systems in mediating the sodium retention associated with glucose ingestion. Eight normotensive men were randomized to receive, after an overnight fast, glucose (1 mg/kg po) in water, and water alone, during two studies seven to ten days apart. Sodium excretion declined 38 +/- 5% from baseline one to two hours after glucose ingestion (P less than .005), but did not change significantly on the control day. Urinary norepinephrine and dopamine did not change during glucose or control studies. Peak serum insulin levels after glucose correlated inversely with the decline in sodium excretion (r = .67, P less than .10). Plasma renin activity (PRA) increased after glucose ingestion (P less than .01), but changes in PRA did not correlate with changes in sodium excretion. We conclude that the antinatriuresis following glucose ingestion does not result from alterations in noradrenergic-dopaminergic activity or changes in the renin-angiotensin-aldosterone axis. Insulin may modulate renal sodium metabolism directly, or through a yet unknown mechanism.

In vivo migration of 111In radiolabeled mouse-spleen lymphocytes and tumor cells.

Mouse-spleen lymphocytes, mouse mammary adenocarcinoma cells (MMA-67) and mouse lymphoma cells (S49.1) were radiolabeled with 111In and their in vivo migration patterns studied over a 24-72 h period after i.v. injection into syngeneic mice. All three cell lines showed different in vivo migration patterns. Initially, some trapping of the cells occurred in the lungs at 15 min. More MMA-67 cells were initially trapped in the lungs than S49.1 cells or lymphocytes. At 24 h, most of the 111In labeled cells had left the lungs and accumulated in various tissues and organs. At 48 and 72 h, only slight changes in the localization patterns of the 111In radiolabeled cells in vivo were noted when compared to the 24 h patterns. About 35% of the injected 111In was excreted from the animals over the 72 h period of these experiments. In vitro studies compared the growth and/or viability of 111In radiolabeled lymphocytes or tumor cells to nonradiolabeled lymphocytes or tumor cells. The percentage of 111In released from the cells in culture was also determined. Similar values for growth and/or viability were obtained between non-radiolabeled cells and MMA-67 cells radiolabeled with 1.35 dpm 111In per cell; S49.1 cells, 0.51 dpm111In per cell; and lymphocytes, 0.04 dpm 111In per cell.