Fatty acid metabolism in normotensive and hypertensive rats I. Differential incorporation of dietary n-3 and n-6 fatty acids

Dietary fatty acids, membrane transport, and oxidative sensitivity in human erythrocytes

This study examined effects of dietary n-3 fatty acids on age-related changes in erythrocyte anion transport and susceptibility to oxidation. Blood was drawn from healthy adult volunteers before and after six weeks' supplementation (nine/group) with 4.0 g/day of safflower oil (containing 2.9 g n-6 fatty acids) or fish oil (containing 1.2 g long-chain n-3 fatty acids). Following density separation of young and old erythrocytes, membrane anion transport and cell membrane lipid composition were measured. Oxidative damage was measured in erythrocyte ghosts exposed to a free radical generator. Fish oil significantly increased 16:0 and 20:5n-3 in ghosts of both young and old cells, and 22:5n-3 and 22:6n-3 in old cells alone. Safflower oil increased 16:0, 18:0, 18:1n-9, and 22:5n-6 in ghosts of young cells only. The age-dependent increase in membrane anion transport (P < 0.01) was decreased by dietary fish oil supplementation, but not by safflower oil supplementation. Safflower oil and fish oil increased the susceptibility of both young and old erythrocytes to oxidative damage by free radical generation (P < 0.001).

Interaction of dietary fatty acids and cyclosporine A in the borderline hypertensive rat: tissue fatty acids

In this study we examined (i) the effects of cyclosporine A (CS) on tissue lipid composition and (ii) the effect of changes in dietary n-6 fatty acids on tissue responses to CS. Fatty acid composition of liver, kidney, heart and brain were determined after 4 wk of treatment with CS (10 mg/kg.d p.o.) in male borderline hypertensive rats (BHR, n = 4/group), whose diet was supplemented with either safflower oil or evening primrose oil (EPO). Phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine/phosphatidylinositol, triglyceride and cholesteryl ester fatty acids were measured in kidney, heart, brain and liver. The same parameters were also measured in safflower-fed BHR (n = 4) receiving placebo. The effects of CS on liver microsomal delta 9, delta 6 and delta 5 desaturases in vitro were also followed. CS affected the fatty acid composition of all tissues examined, with the greatest changes seen in the renal phosphatidylcholine and phosphatidylserine/phosphatidylinositol fractions. All CS-induced changes that occurred in the liver, brain and renal fatty acids were reversed by EPO. CS elevated delta 9 desaturase but had no effect on delta 6 and delta 5 desaturase. In light of (i) the observation that EPO normalizes renal function and blood pressure in CS-treated BHR, and (ii) the importance of the kidney in blood pressure regulation, the data suggest that the beneficial effects of EPO on CS toxicity may involve changes in renal phospholipid fatty acid profiles.

Effects of dietary fatty-acid supplementation on fatty-acid composition and deformability of young and old erythrocytes

The effects of cell age on erythrocyte phospholipid fatty-acid composition and deformability were examined in 20 healthy adults (11 male, 9 female) prior to and following 12 weeks of dietary supplementation with 3.5 g/day of safflower oil (high in n - 6 fatty acids) or fish oil (high in n - 3 fatty acids). In the absence of dietary supplementation, old erythrocytes demonstrated an increase in filtration time (P < 0.001), an increase in membrane phospholipid total n - 6 fatty acids (P < 0.01), and a decrease in total n - 3/total n - 6 ratio (P < 0.01) compared to young erythrocytes. Both safflower and fish oil supplementation attenuated age-related differences in membrane phospholipid total n - 6 and total n - 3 fatty acids. Fish oil supplementation also increased the proportion of n - 3 fatty acids (P < 0.01) and the n - 3/n - 6 ratio (P < 0.05) in the phospholipids of both young and old erythrocytes, and eliminated age-related differences in erythrocyte filtration time by reducing the relative filtration time of the old erythrocytes.