Dietary linoleic acid prevents the development of deoxycorticosterone acetate-salt hypertension.

Abstract

The aim of this study was to elucidate the effect of dietary variations of linoleic acid on the development of deoxycorticosterone acetate (DOCA)-salt hypertension in rats. All rats were divided into three groups and fed one of the following isocaloric diets with 8% NaCl: a high linoleic acid (HLA) (20% sunflower oil), a moderate linoleic acid (5% lard oil+15% sunflower oil), or a low linoleic acid (DLA) (20% lard oil). After 4 weeks of feeding, we determined intraerythrocyte sodium, potassium, and magnesium concentrations, intra-aortic and lymphocyte magnesium content, and erythrocyte ouabain-sensitive "Na efflux rate constant. Cytoplasmic free calcium concentration of lymphocytes from thymus was also determined with quin-2 as a fluorescent indicator. In the HLA group, the elevation of systolic blood pressure was significantly attenuated, and intraerythrocyte sodium concentration was significantly lower than in the DLA group. There were greater intraerythrocyte potassium and magnesium concentrations, intra-aortic and lymphocyte magnesium contents, and erythrocyte ouabainsensitive u Na efflux rate constant in the HLA group as compared with other groups. Cytoplasmic free calcium concentration in the HLA group was significantly lower than in other groups. Systolic blood pressure significantly correlated negatively with intraerythrocyte and intra-aortic magnesium concentrations and intraerythrocyte potassium concentration, and correlated positively with cytoplasmic free calcium concentration. Erythrocyte ouabainsensitive a Na efflux rate constant significantly correlated positively with intraerythrocyte magnesium concentration. These findings suggest that dietary linoleic acid can attenuate the development of DOCA-salt hypertension. It is assumed that the mechanism of its hypotensive effect might be because of a decrease in intracellular sodium and calcium concentration and an increase in intracellular magnesium content, resulting in the elevation of sodium-potassium pump activity. (Hypertension 1990;15(suppl I):I-81-I-87)

Lack of effect on blood pressure by low fat diets with different fatty acid compositions

“…In addition, the 1980 diet was higher in salt, and in the experi- mental studies in rats the BP response to dietary fat modification was most evident in animals with low baseline PUFA and high sodium intake. 2,3 The changes in the background diet between early 1980s and the 1990s in North Karelia have been similar to those found in all parts of Finland. 52 The total fat intake of the population has decreased due to reduced intake of SAFA, and the consumption of PUFA has increased concomitantly.…”

“…2,3 In man the effects of dietary fat on BP have been extensively studied, but the results of both observational studies and intervention trials have been conflicting as summarised in several review articles. [4][5][6][7][8] Total fat intake has not been associated with BP in human cross-sectional studies.…”

Linoleic Acid Induces Relaxation and Hyperpolarization of the Pig Coronary Artery

“…The hypotensive effect of linoleic acid in deoxycorticosterone acetate-salt hypertension in rats was correlated with increases in the activity of the Na ϩ /K ϩ -ATPase pump. 15 Thus, it may be possible that linoleic acid, by increasing fluidity, activates the pump, which in turn alters the membrane potential of VSMC, causing vasodilation. Although arachidonic and linoleic acids have been reported to have an inhibitory effect on Na ϩ /K ϩ -ATPase, 38 unsaturated fatty acids have recently been shown to activate the Na ϩ /K ϩ -ATPase pump, while saturated fatty acids such as palmitic acid had little or no effect.…”

“…15 It has also been shown that gamma-linolenic acid, a metabolite of linoleic acid, attenuates stress-induced hypertension.…”

“…12,13 Linoleic acid inhibits salt-induced hypertension 14 as well as deoxycorticosterone acetate-salt hypertension in rats. 15 It has also been shown that gamma-linolenic acid, a metabolite of linoleic acid, attenuates stress-induced hypertension. 16 Diets enriched with linoleic or gamma-linolenic acid lower blood pressure in hypertensive humans 17 and attenuate the development of hypertension in SHR.…”