gamma-linolenic-acid and Hypertension

Topics: alpha-Linolenic Acid; Anti-Inflammatory Agents, Non-Steroidal; Antihypertensive Agents; Arthritis; Blood Pressure; Coronary Artery Disease; Dermatitis; Dermatologic Agents; Fatty Acids, Essential; gamma-Linolenic Acid; Humans; Hypertension; Hypolipidemic Agents; Linoleic Acids; Lipids; Oenothera biennis; Plant Oils; Platelet Aggregation; Treatment Outcome

Systemic arterial hypertension and obesity are major public health problems that increase risks of serious cardiovascular diseases and kidney failure as well as increase mortality. Substances that can alleviate these problems are desirable. We evaluated the beneficial effects of nutritional supplementation with gamma-linolenic acid in postmenopausal hypertensive women.. This was a prospective, double-blind, placebo-controlled, randomized study involving 96 postmenopausal women. Participants were divided into two groups either receiving 1,000 mg of borage oil rich in gamma-linolenic acid + vitamin E (drug) or only vitamin E (placebo) capsules for 6 months. They were followed up monthly to assess the impact on systemic blood pressure and body composition. To verify group homogeneity, Fisher's exact and Student t tests were performed. To evaluate differences in various parameters between the two groups and at various times, repeated measures analysis of variance was performed, with Bonferroni correction.. The power of the test was calculated based on the difference in the mean systolic blood pressure between baseline and after 6 months of treatment in the placebo group and in the drug group. A 92.9% test power was found with a 95% confidence interval. There was a significant reduction in the systolic and diastolic pressure as well as a significant change in waist-hip ratio (P < 0.01) in the drug group as compared with the placebo group.. Supplementation with borage oil rich in gamma-linolenic acid had significant beneficial short-term effects without showing any adverse effect. There remains a need for further studies to evaluate long-term benefits.

Topics: Adipose Tissue; Dietary Supplements; Double-Blind Method; Female; gamma-Linolenic Acid; Humans; Hypertension; Postmenopause; Prospective Studies

Inflammation plays a key role and is one of the early steps in the pathogenesis of endothelial function, thereby increasing the risk of hypertension (HTN), coronary artery disease (CAD), stroke and several other risk factors of cardiovascular disease (CVD). We assessed the efficacy for improving cardiovascular health (blood pressure, inflammation and endothelial reactivity) over a 4-week intervention period in healthy individuals.. We performed a randomized, double-blinded, placebo-controlled, randomized clinical trial to investigate Curcumin, Eicosapentaenoic acid (EPA), Astaxanthin and Gamma -linoleic acid (GLA) (CEAG) supplements with 80 individuals (30 men and 50 women). The mean age of participants was 48.8 ± 16.0 years. Participants were enrolled and randomized to active or placebo and followed for 4 weeks. Paired and Independent T-tests were used to analyze the mean differences between and within groups.. The primary endpoints of the study were the effect on inflammatory markers (IL-6, CRP), endothelial function and blood pressure at 4 weeks. There was a significant reduction in mean SBP at 4 weeks in the CEAG group compared to placebo [mean ± SD 4.7 ± 6.8 (p = 0.002)]. Relative to placebo, active group showed a significant decrease in High sensitivity C Reactive Protein (hsCRP) (-0.49 ± 1.9 vs + 0.51 ± 2.5, p = 0.059) and blunted increase in IL-6 (+0.2 vs + 0.4 in placebo, p = 0.60).. Inflammatory markers were reduced or blunted by CEAG, with a robust increase in both EPA levels and the fatty acid index. Furthermore, systolic BP was reduced over 4 weeks with concurrent improvement in endothelial function. CLINICALTRIALS.. NCT03906825.

Topics: Adolescent; Adult; Aged; Biomarkers; Blood Pressure; C-Reactive Protein; Cardiovascular Diseases; Coronary Artery Disease; Dietary Supplements; Double-Blind Method; Eicosapentaenoic Acid; Endothelium; Fatty Acids, Omega-3; Female; gamma-Linolenic Acid; Healthy Volunteers; Humans; Hypertension; Interleukin-6; Male; Middle Aged; Xanthophylls; Young Adult

Although omega-3 polyunsaturated fatty acid supplements reduce blood pressure (BP), the typical doses cause untoward side effects. A novel fatty acid supplement was tested in a randomized trial of patients with high normal diastolic BP. The novel fatty acid supplement did not significantly reduce BP in patients with high normal diastolic blood pressure.

Topics: Blood Pressure; Capsules; Drug Combinations; Eicosapentaenoic Acid; Female; gamma-Linolenic Acid; Humans; Hypertension; Male; Middle Aged

The objective of this study was to test the effect of a supplement of blackcurrant seed oil (BSO), a rich source of gamma-linolenic acid (C18:3n-6) on the resting blood pressure (BP) and cardiovascular reactivity to a psychological stress in borderline hypertensive individuals. Twenty-seven male volunteers found to have a BP lying persistently within the borderline range, were allocated randomly to one of two groups at the end of a 4-week baseline period. The first group received a daily supplement of 6 g safflower oil for the consecutive 8 weeks while the second the same dose of blackcurrant seed oil. In addition to weekly measurements of resting BP, BP and heart rate reactivity to a standardised 5-min test of mental arithmetic were recorded before, and at the end of the supplementation period. BSO inhibited BP reactivity by over 40% (ANOVA for repeated measures diastolic (D) BP P = 0.026, systolic (S) BP P = 0.021). The decrease in DBP for the subjects on BSO was significantly different from the slight changes observed in the safflower group (ANOVA for repeated measures P = 0.018 for time-treatment interaction). We conclude that gamma-linolenic-rich fatty acid preparations are likely to influence cardiovascular control, by mechanisms yet to be clarified.

Topics: Antihypertensive Agents; Blood Pressure; gamma-Linolenic Acid; Heart Rate; Humans; Hypertension; Male; Plant Oils; Problem Solving; Stress, Psychological

Atherosclerosis is associated with various cardiovascular diseases (CVDs). Measurement of arterial stiffness using pulse wave velocity (PWV) enables assessment of atherosclerosis progression in individuals. The authors screened patients with asymptomatic atherosclerosis, based on the PWV findings, to evaluate appropriate early interventions and assess the efficacy of γ-linolenic acid, Vitis vinifera extract, and acetyl-L-carnitine triple combination therapy in atherosclerosis prevention. This retrospective study analyzed the medical records of adult patients between March 2007 and April 2019, with presenting complaints of fatigue and lethargy. Among patients with vascular stiffness beyond their biological age on brachial-ankle PWV (baPWV) testing, those with ≥80% compliance for three drugs were allocated to the experimental group. Those with compliance of <80% for any one drug were allocated to the control group to assess changes in arterial stiffness, fasting plasma glucose (FPG), lipid level, and blood pressure (BP). After 1 year of triple-combination therapy, there were significant decreases in right and left baPWV (1537.16 ± 274.84 and 1519.00 ± 289.32 cm/s, respectively) as compared to baseline (1633.15 ± 271. 20 and 1598.64 ± 267.95 cm/s, respectively; p < .001). There was no difference in baPWV between sexes. Moreover, neither group showed significant changes in FPG and lipid levels. When triple-combination therapy combining γ-linolenic acid, V. vinifera extract, and acetyl-L-carnitine was administered to patients with high arterial stiffness relative to their age, as assessed by baPWV, the experimental group showed a decrease in arterial stiffness in both sexes.

Topics: Acetylcarnitine; Adult; Atherosclerosis; Female; gamma-Linolenic Acid; Humans; Hypertension; Male; Plant Extracts; Pulse Wave Analysis; Republic of Korea; Retrospective Studies; Vascular Stiffness; Vitis

Dietary gamma-linolenic acid (GLA), a omega-6 polyunsaturated fatty acid found in borage oil (BOR), lowers systolic blood pressure in spontaneously hypertensive rats (SHRs). GLA is converted into arachidonic acid (AA) by elongation and desaturation steps. Epoxyeicosatrienoic acids (EETs) and 20-hydroxyeicosatetraenoic acid (20-HETE) are cytochrome P450 (P450)-derived AA eicosanoids with important roles in regulating blood pressure. This study tested the hypothesis that the blood pressure-lowering effect of a GLA-enriched diet involves alteration of P450-catalyzed AA metabolism. Microsomes and RNA were isolated from the renal cortex of male SHRs fed a basal fat-free diet for 5 weeks to which 11% by weight of sesame oil (SES) or BOR was added. There was a 2.6- to 3.5-fold increase in P450 epoxygenase activity in renal microsomes isolated from the BOR-fed SHRs compared with the SES-fed rats. Epoxygenase activity accounted for 58% of the total AA metabolism in the BOR-treated kidney microsomes compared with 33% in the SES-treated rats. More importantly, renal 14,15- and 8,9-EET levels increased 1.6- to 2.5-fold after dietary BOR treatment. The increase in EET formation is consistent with increases in CYP2C23, CYP2C11, and CYP2J protein levels. There were no differences in the level of renal P450 epoxygenase mRNA between the SES- and BOR-treated rats. Enhanced synthesis of the vasodilatory EETs and decreased formation of the vasoconstrictive 20-HETE suggests that changes in P450-mediated AA metabolism may contribute, at least in part, to the blood pressure-lowering effect of a BOR-enriched diet.

Topics: Animals; Arachidonic Acids; Blotting, Western; Cytochrome P-450 CYP2J2; Cytochrome P-450 Enzyme System; Dietary Fats; Enzyme Induction; gamma-Linolenic Acid; Hypertension; Kidney; Male; Oxygenases; Rats; Rats, Inbred SHR

gamma-Linolenic acid [GLA, 18:3(n-6)], eicosapentaenoic acid [EPA, 20:5(n-3)] and docosahexaenoic acid [DHA, 22:6(n-3)] have been reported to prevent cardiovascular diseases. However, they are highly unsaturated and therefore more sensitive to oxidation damage. We investigated the effects of a diet rich in these polyunsaturated fatty acids (PUFA) on blood pressure, plasma and lipoprotein lipid concentrations, total antioxidant status, lipid peroxidation and platelet function in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Five-week-old SHR and WKY rats were fed for 10 wk either a diet containing Isio 4 oil or a diet rich in GLA, EPA and DHA (5.65, 6.39 and 4.94 g/kg dry diet, respectively). The total antioxidant status was assayed by monitoring the rate of free radical-induced hemolysis. VLDL-LDL sensitivity to copper-induced lipid peroxidation was determined as the production of thiobarbituric acid reactive substances. After dietary PUFA supplementation, a significant decrease in blood pressure of SHR rats (-20 mm Hg) was observed and the total antioxidant status was enhanced. VLDL-LDL resistance to copper-induced peroxidation was increased in both strains. The PUFA supplementation did not change platelet maximum aggregation in SHR rats, but it decreased the aggregation speed. In hypertensive rats, GLA + EPA + DHA supplementation lowers blood pressure, enhances total anti-oxidant status and resistance to lipid peroxidation, diminishes platelet aggregation speed and lowers plasma lipid concentrations. Thus, it enhances protection against cardiovascular diseases. Therefore, nutritional recommendations for cardiovascular disease prevention should take into account the pharmacologic properties of GLA, EPA and DHA.

Topics: Animals; Antioxidants; Blood Pressure; Dietary Fats; Docosahexaenoic Acids; Eicosapentaenoic Acid; Fatty Acids, Unsaturated; gamma-Linolenic Acid; Hypertension; Lipid Peroxides; Lipids; Platelet Aggregation; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Time Factors

In a previous study, we showed that dietary gamma-linolenic acid (GLA), an omega-6 polyunsaturated fatty acid found in borage oil (BOR), attenuates the development of hypertension in young spontaneously hypertensive rats (SHR). The purpose of this study was to determine the effects of dietary GLA on established hypertension in adult rats, as well as its effects on components of the renin-angiotensin-aldosterone axis. For 5 weeks, male SHR (14-15 weeks old) were fed a basal fat-free diet to which 11% by weight of sesame oil (SES) or BOR was added. Systolic blood pressure (SBP), determined by the tail cuff method, and weight were measured weekly. Plasma renin activity (PRA), aldosterone (PA), and corticosterone (PC) levels were measured at the end of the dietary treatments. The adrenal glands were homogenized, and angiotensin II (ANG II) binding was measured and plotted according to Scatchard. Systolic blood pressure was 12 mmHg lower at Week 5 in SHR fed the BOR diet compared to SES-fed rats (P < 0.005). Weight gains were similar in both dietary groups. Plasma aldosterone was lower, PRA was higher, and the PA/PRA ratio was significantly lower (P < 0.05) in BOR-fed rats. Levels of PC were the same in both groups. The BOR-enriched diet reduced adrenal ANG II receptor density and affinity compared to the SES diet. Results suggest that BOR inhibits adrenal responsiveness to ANG II by an action on adrenal receptors. Our findings demonstrated that dietary GLA lowers SBP in adult SHR. This effect may be mediated, at least in part, by interference with the renin-angiotensin-aldosterone system at the level of adrenal ANG II receptors.

Topics: Adrenal Glands; Aldosterone; Angiotensin II; Animals; Blood Pressure; Corticosterone; Dietary Fats, Unsaturated; gamma-Linolenic Acid; Hypertension; Male; Rats; Rats, Inbred SHR; Receptors, Angiotensin; Renin

We have recently reported that cyclosporine A (CsA) decreases glomerular filtration rate in the borderline hypertensive rat (BHR), but that the glomerular filtration rate is normal when the rats are maintained on a diet supplemented with evening primrose (EP) oil. The current studies were designed to determine the glomerular hemodynamic changes responsible for this effect. A first group (PLAC-SAFF) received a diet supplemented with safflower oil (SAFF) (10% of calories) and placebo (PLAC). A second group (CsA-SAFF) received a diet supplemented with SAFF and CsA (10 mg/kg/day). A third group (CsA-EP) also received CsA, but the diet was supplemented with EP oil (10% of calories). Routine micropuncture studies were performed after five to nine weeks of treatment. Single nephron glomerular filtration rate (SNGFR) was lower in CsA-SAFF than in PLAC-SAFF (36 +/- 2 vs. 46 +/- 1 nl/min, p < 0.05). Maintenance of SNGFR in CsA-EP compared to CsA-SAFF (48 +/- 2 nl/min vs. 36 +/- 2 nl/min, P < 0.05) was due to higher values for single nephron plasma flow rate (156 +/- 16 vs. 118 +/- 9off/min, P < 0.05), and higher values for the glomerular capillary ultrafiltration coefficient (0.091 +/- 0.013 vs. 0.054 +/- 0.010 nl/s/mm Hg, P < 0.05). Since dietary fatty acids can affect prostaglandin (PG) production, we measured PGE production in isolated glomeruli. Mean values for basal production rates of PGE were greater in rats maintained on EP than in rats maintained on SAFF (3958 +/- 105 vs. 3378 +/- 146 pg PGE/mg glomerular protein, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Cyclosporine; Dietary Fats; Eicosanoids; Fatty Acids, Essential; gamma-Linolenic Acid; Glomerular Filtration Rate; Hemodynamics; Hypertension; Kidney Glomerulus; Linoleic Acids; Male; Oenothera biennis; Plant Oils; Punctures; Radioimmunoassay; Rats; Rats, Inbred Strains; Safflower Oil

1. The present study was performed to determine whether chronic treatments with gamma linolenic acid (n-6, GLA) or eicosapentaenoic acid (n-3, EPA) would alter serum and red blood cell (RBC) unsaturated fatty acid composition, and to determine whether these treatments would affect blood pressure (BP), serum lipid metabolism and the development of atherosclerosis in spontaneously hypertensive rats (SHR). 2. To compare the effects on atherosclerosis, some SHR were denuded of aortic endothelium so that the development of atherosclerosis would be accelerated. Olive oil (control), GLA or EPA (low dose: 5 mg/day per rat, high dose: 50 mg/day per kg, respectively) was administered intraperitoneally for 6 weeks in SHR. 3. GLA treatments increased GLA and its metabolite, dihomo-GLA, levels in serum but not in RBC, while EPA treatments increased EPA level both in serum and in RBC. 4. The BP of control SHR was further elevated. EPA significantly reduced this elevation of systolic, mean and diastolic pressure within the first week and thereafter, whereas GLA did not affect BP elevation. Neither heart rate or bodyweight gain was affected by these treatments. 5. Serum total cholesterol (TC), triglyceride (TG), and glucose (G) levels and the development of atherosclerosis were unaffected by either GLA or EPA treatment. 6. In summary, chronic EPA but not GLA treatment slightly reduced BP elevation in SHR. Although chronic GLA or EPA treatment increased the respective serum level, these treatments unaltered serum TC, TG and G levels, and could not prevent the development of aortic atherosclerosis in SHR.

Topics: Animals; Arteriosclerosis; Blood Pressure; Eicosapentaenoic Acid; Erythrocytes; gamma-Linolenic Acid; Hypertension; Lipids; Male; Rats; Rats, Inbred SHR

The effects of oils enriched with gamma-linolenic acid (GLA) on blood pressure and pressor responses were examined in spontaneously hypertensive rats (SHR). Rats were fed purified diets containing evening primrose (EPO), black currant (BCO), borage (BOR) or fungal (FGO) oils for 7 weeks. Significant reductions in blood pressure were obtained in SHR rats maintained on diets enriched with GLA oils. The antihypertensive effect was not associated with enhanced pressor responsiveness to norepinephrine or angiotensin II. Moreover, no differences were found in blood pressure responses to the calcium channel blocker, verapamil. The results suggest that GLA-enriched oils inhibit the development of hypertension in the SHR rat. The blood pressure lowering effect is not mediated by altered pressor responses to vasoconstrictor hormones or intracellular calcium mechanisms.

Topics: Animals; Blood Pressure; Dietary Fats; Fatty Acids; Fatty Acids, Essential; gamma-Linolenic Acid; Hypertension; Linoleic Acids; Male; Oenothera biennis; Plant Oils; Rats; Rats, Inbred SHR; Sesame Oil; Vasoconstriction

Spontaneously hypertensive rats (SHR) respond to angiotensin and norepinephrine with an exaggerated pressor response. We have investigated the possibility that increased vascular reactivity in SHR may be related to a reduced synthesis of prostaglandin E1 (PGE1) resulting from a defect in the release of its precursor, dihomo-gamma-linoleic acid (DGLA). Isolated perfused mesenteric vascular beds of SHR and age matched Wistar-Kyoto rats (WKY) were perfused with Kreb's bicarbonate buffer. The effluent was collected and the fatty acid composition determined by gas chromatography. In SHR the release of DGLA, arachidonic acid, eicosapentaenoic acid, and virtually all other fatty acids detected in the effluent were reduced when compared to their normotensive controls. This difference could not be explained by low tissue fatty acid levels because these were higher in SHR. Evening primrose oil (EPO) when added to the diet increased the release of DGLA but not of other prostanoid precursors. EPO also reduced vascular reactivity and reduced blood pressure in SHR. It is suggested that the defect in the release of DGLA may be involved in the pathogenesis of hypertension because it occurs early before hypertension has actually occurred.

Topics: 8,11,14-Eicosatrienoic Acid; Alprostadil; Animals; Arachidonic Acid; Blood Pressure; Chromatography, Gas; Eicosapentaenoic Acid; Fatty Acids; Fatty Acids, Essential; gamma-Linolenic Acid; Hypertension; Hypolipidemic Agents; Linoleic Acids; Male; Mesentery; Norepinephrine; Oenothera biennis; Plant Oils; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Vascular Resistance

The present study compared the effect of spontaneous hypertension and salt-loading on in vitro metabolism of 18:2n-6 (linoleic acid) and 20:3n-6 (dihomo-gamma-linolenic acid). Ten weanling spontaneously hypertensive rats (SHR) and 10 normotensive Wistar-Kyoto rats (WKY) maintained on a rodent lab chow were given tap water with (n = 5) or without (n = 5) addition of 1% NaCl for 4 weeks. Thereafter, animals were killed and liver microsomes were prepared. Aliquots of microsomes suspended in the phosphate-sucrose buffer containing MgCl2, ATP, CoA, and NADPH were incubated with 0.3 microCi of [1-14C]-18:2n-6 or [2-14C]-20:3n-6 at 37 degrees C for 15 min. The activity of delta 6- and delta 5-desaturases, and the distribution of radioactivity in different lipid fractions and in phospholipid fatty acids were determined. Results showed that both spontaneous hypertension and salt-loading suppressed the desaturation of radiolabeled 18:2n-6 and of 20:3n-6. Incubation of microsomes with [1-14C]-18:2n-6 resulted in 29% of radioactivity being associated with phospholipid fraction, of which 3% was associated with 18:3n-6. Incubation with radiolabeled 20:3n-6 resulted in 30% of the radioactivity being incorporated into phospholipids, of which 50% was associated with 20:4n-6 (arachidonic acid). Salt-loading suppressed the incorporation of radiolabeled fatty acids into phospholipids, more so in SHR than in WKY. Thus, salt-loading not only suppressed the desaturation of 18:2n-6 and 20:3n-6, but also interfered with the acylation of n-6 fatty acids into the phospholipid fraction.

Topics: Animals; Fatty Acid Desaturases; gamma-Linolenic Acid; Hypertension; In Vitro Techniques; Linoleic Acid; Linoleic Acids; Linolenic Acids; Male; Microsomes, Liver; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Sodium Chloride

To determine the effects of dietary gamma-linolenic acid upon blood pressure, aortic reactivity and cholesterol metabolism in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats.. Randomized parallel-group study.. SHR and WKY rats were fed a purified diet containing either sesame or borage oil rich in gamma-linolenic acid for 7 weeks. Blood pressure measured by the tail-cuff method and weight were monitored weekly. At the end of the study, intra-arterial pressor responses to norepinephrine and angiotensin II, and reactivity of isolated aortic rings to norepinephrine, angiotensin II, KCl and acetylcholine were determined. Serum cholesterol and triglycerides were measured. Hepatic and intestinal enzymes and receptors of cholesterol metabolism were also measured.. Dietary borage oil significantly decreased blood pressure in SHR and WKY rats compared with sesame oil-fed rats. Pressor responses to norepinephrine and angiotensin II, and aortic reactivity to norepinephrine, angiotensin II, KCl and acetylcholine were not significantly different. The borage oil diet increased serum cholesterol levels in WKY rats and hepatic B-hydroxy-3-methylglutaryl coenzyme A reductase in SHR.. These data indicate that dietary borage oil has a blood pressure lowering effect in hypertensive and normotensive rats. However, the effect cannot be explained by altered sensitivity to humoral and neural vasoconstrictors or changes in cholesterol metabolism. Other mechanisms should be investigated.

Topics: Angiotensin II; Animals; Aorta; Blood Glucose; Blood Pressure; Cholesterol; Dietary Fats, Unsaturated; Electrolytes; gamma-Linolenic Acid; Hypertension; Linolenic Acids; Male; Norepinephrine; Plant Oils; Random Allocation; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Sesame Oil; Triglycerides

Spontaneously hypertensive rats (SHR) at 4 weeks of age were fed a diet supplemented with sunflowerseed oil (SO), evening primrose oil (EPO), fish oil (FO) or EPO + FO for 22 weeks. A diet with commercially available pellets served as control. Systolic blood pressure was significantly lower during and after FO, EPO and EPO + FO, whereas the lower level after SO was not significant when compared with the controls. Serum triglycerides and total cholesterol were lowest after EPO followed FO. The combination of both EPO and FO resulted in unexpected high values of triglycerides and cholesterol. HDL-cholesterol was likewise highest after EPO + FO. The results indicate a quantitatively different depression of blood pressure and serum lipids from SHR by individual polyunsaturated fatty acids (PUFA).

Topics: Animals; Blood Pressure; Body Weight; Cholesterol, HDL; Fatty Acids, Essential; Fish Oils; Food, Fortified; gamma-Linolenic Acid; Heart Rate; Hypertension; Hypolipidemic Agents; Linoleic Acids; Lipids; Male; Oenothera biennis; Plant Oils; Rats; Rats, Inbred SHR; Sunflower Oil; Triglycerides

It has been suggested that dietary linoleic and gamma-linolenic acid may be hypotensive. Fat enriched diets increase blood pressure, and the effects of linoleic and linolenic acids on this increase have been investigated. After a control period on a low fat diet, rabbits were given four fat enriched diets containing different proportions of linoleic, gamma-linolenic and alpha-linolenic acids for 8 weeks, and returned to the low fat control diet for 3 weeks. Blood pressures were measured non-invasively every day. Blood pressures increased from the 4th week of fat feeding. The blood pressure increase at 8 weeks was 10%, 13%, 15% and 14% respectively for primrose, starflower, safflower and olive oils (all P less than 0.001). Return to the low fat control diet for 3 weeks restored blood pressures to near control values. These results do not support the suggestion that either linoleic or gamma-linolenic acids are effective antihypertensive agents.

Topics: Animals; Blood Pressure; Dietary Fats; gamma-Linolenic Acid; Hypertension; Linoleic Acids; Linolenic Acids; Plant Oils; Rabbits

Dietary supplementation with 3 g/day linoleic acid, 32 mg/day gammalinolenic acid and co-factors for prostaglandin synthesis was given to 10 pregnant and 10 non-pregnant subjects for a week. Their pressor response to the infusion of three doses of angiotensin II (AII) (pregnant: 4, 8, 16 ng kg-1 min-1: non-pregnant: 1, 2, 4 ng kg-1 min-1) was then compared with that of 40 pregnant and 24 non-pregnant controls who had not been given such supplementation. Dietary supplementation was not associated with changes in basal systolic or diastolic blood pressure or heart rate during the week of treatment in pregnant or non-pregnant subjects. Basal systolic blood pressure, diastolic blood pressure and heart rate values did not differ between the treated and untreated subjects in each group. The diastolic pressor response to AII was significantly less after treatment at all doses; the effect was more marked in the pregnant subjects. The systolic response to AII, normally less than the diastolic, was somewhat blunted in the treated pregnant patients at the two higher infusion doses. No significant effect was found in the non-pregnant group. Evidence from other studies suggests that increasing plasma linoleic acid concentrations leads to increased plasma concentrations of epoprostenol (prostacyclin, PGI2) while increased availability of gammalinolenic acid is associated with a rise in prostaglandin E1 and E2 production. Pregnancy-induced hypertension is associated with a diminished tissue production of both epoprostenol and E series prostaglandins, and with an enhanced pressor response to AII.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Angiotensin II; Blood Pressure; Diet; Female; gamma-Linolenic Acid; Heart Rate; Humans; Hypertension; Linoleic Acid; Linoleic Acids; Linolenic Acids; Pregnancy; Pregnancy Complications, Cardiovascular; Vitamins

The purpose of the present study was to investigate the effects of gamma linolenic acid (GLA) on cardiovascular responses to psychosocial stress (isolation) and to pressor hormones in the genetically borderline hypertensive rat (SHR X WKY). Adult male SHR X WKY were divided into two groups following five weeks of group housing. One group (GLA) received eight weeks constant flow osmotic pumps releasing 0.04 mg GLA in olive oil/kg-hr, while the second group received dummy pumps (DUM). One week following pump implantation, each group was divided into two subgroups and exposed to a four-week experimental period of either continued group housing (no stress) or isolation (stress). A two-week recovery period of group housing followed the experimental period. Blood pressure and heart rate were determined weekly by the tail cuff technique. At the end of the recovery period, animals in the no stress condition were anesthetized and received an arterial cannula for NOR and ANG infusion and direct BP recording. Then the responses to an ED50 of NOR and ANG were determined. All animals were then killed for determination of heart weight and adrenal weight. All groups had mean control period systolic BP values ranging from 143-146 mm Hg. In the no stress condition, neither GLA nor DUM altered BP over the course of the study. However, BP increased in the DUM group during all four weeks of the isolation period vs the control period (p less than 0.01), whereas BP increased only in week 1 in the GLA group (p less than 0.05). Heart rate increased during stress in the DUM group (p less than 0.05), but not in the GLA group. Vascular reactivity to NOR was unaffected by GLA administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Blood Pressure; Body Weight; Female; gamma-Linolenic Acid; Heart; Heart Rate; Hypertension; Linolenic Acids; Male; Organ Size; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Social Isolation; Stress, Physiological

Spontaneously hypertensive rats (SHR) were fed a basal regular diet (BD) or three different fat-supplemented diets which contained 10% hydrogenated coconut oil (HCO), 10% safflower oil (SFO), or 10% evening primrose oil (EPO). The rats received these four different diets from 4 weeks to over 24 weeks of age. The development of hypertension in SHR was significantly retarded in the EPO-supplemented animals. The blood pressure was lower in the SFO group animals as compared with the BD and HCO groups, but this did not reach significance. Sodium excretion rate in young SHR was increased in the EPO group compared with the HCO and SFO groups, and the urinary K/Na ratio was decreased in the EPO group compared with the HCO and EPO groups. Water intake and urine volume were increased in the SFO group as compared with the HCO and EPO groups. Sodium concentration in erythrocytes was decreased in the rats receiving SFO. Pressor responses to norepinephrine and angiotensin II were enhanced in the EPO and SFO groups as compared with the basal chow group. These data suggest that a dietary supplementation of EPO which contains a substantial amount of gamma-linolenic acid consistently lowers blood pressure in SHR. The mechanism is uncertain, but the effects on sodium handling may in part be responsible for the retardation of the development of hypertension. There was a difference between the EPO and the SFO groups in sodium--water handling, and to some extent in the blood pressure development in SHR.

Topics: Angiotensin II; Animals; Blood Pressure; Body Weight; Coconut Oil; Dietary Fats; Drinking; Erythrocytes; Fatty Acids; Fatty Acids, Essential; Fatty Acids, Unsaturated; gamma-Linolenic Acid; Hypertension; Linoleic Acids; Male; Norepinephrine; Oenothera biennis; Oils; Plant Oils; Potassium; Rats; Rats, Inbred SHR; Safflower Oil; Sodium

Topics: alpha-Linolenic Acid; Animals; Blood Pressure; Dietary Fats; Fatty Acids, Essential; Fatty Acids, Unsaturated; gamma-Linolenic Acid; Hypertension; Linoleic Acid; Linoleic Acids; Linolenic Acids; Linseed Oil; Male; Oenothera biennis; Oils; Plant Oils; Rats; Rats, Inbred SHR; Sunflower Oil

This study investigated a model of psychosocial stress-induced hypertension in the rat, and examined effects of the prostaglandin E precursor, gamma-linolenic acid (GLA) on the development of hypertension during psychosocial stress. In the first study, male rats were housed four/cage for an acclimation period of 21 days, followed by a 14-day control period. An experimental group (N = 12) was then placed in isolation cages for 14 days, then regrouped for a 7-day recovery period. Controls (N = 12) remained group-housed. Eight animals per group were sacrificed after the experimental period, and four per group after recovery for organ weight analysis. Mean systolic blood pressure (BP) was similar between groups during the control period (126 +/- 2 and 125 +/- 2 mm Hg), but increased during isolation, reaching 140 +/- 2 mm Hg (P less than 0.001) by Day 14. During recovery BP returned to control levels. No changes in heart rate, heart weight/body weight or adrenal weight were seen. The second study utilized a protocol similar to that of the experimental group of the first study, minus the recovery period. On Day 1 of the control period 28-day osmotic pumps were implanted ip, releasing olive oil or GLA in olive oil. Four groups of rats (N = 8/group) received either (i) olive oil (controls), (ii) 0.018 mg GLA/hr, (iii) 0.040 mg GLA/hr, or (iv) 0.040 mg GLA/hr with no stress. Organ weights were obtained following stress in groups 1-3. Controls developed a sustained elevation in BP within 24 hr of isolation. Animals receiving 0.018 mg GLA/hr developed elevated BP upon isolation, but the BP was less than that of controls on Days 1 (P less than 0.05) and 14 (P less than 0.001) of isolation. Animals receiving 0.040 mg GLA/hr demonstrated a greatly attenuated rise in BP vs controls (P less than 0.001) on all isolation days. GLA in unstressed rats had no effect on BP. Heart rate, heart weight/body weight, and adrenal weight were unchanged in all groups. These data suggest that (i) isolation is a useful tool for investigating reversible psychosocial stress-induced hypertension, and (ii) GLA, while not affecting BP in unstressed animals, produces a dose-dependent attenuation of the BP response to chronic stress.

Topics: Adrenal Glands; Animals; Antihypertensive Agents; Blood Pressure; gamma-Linolenic Acid; Heart; Humans; Hypertension; Linolenic Acids; Male; Organ Size; Rats; Rats, Inbred Strains; Social Isolation; Stress, Psychological

Topics: Animals; Blood Pressure; Dietary Fats; Fatty Acids; Fatty Acids, Essential; Fatty Acids, Unsaturated; gamma-Linolenic Acid; Hypertension; Linoleic Acids; Linseed Oil; Male; Oenothera biennis; Oils; Plant Oils; Rats; Rats, Inbred Strains; Sunflower Oil