12-hydroxy-5-8-10-14-eicosatetraenoic-acid and Hypertension

Post-exercise hypotension (PEH) is the phenomenon of lowered blood pressure after a single bout of exercise. Only a fraction of people develops PEH but its occurrence correlates well with long-term effects of sports on blood pressure. Therefore, PEH has been suggested as a suitable predictor for the effectivity of exercise as therapy in hypertension. Local vascular bioactive lipids might play a potential role in this context. We performed a cross-over clinical pilot study with 18 healthy volunteers to investigate the occurrence of PEH after a single short-term endurance exercise. Furthermore, we investigated the plasma lipid profile with focus on arachidonic acid (AA)-derived metabolites as potential biomarkers of PEH. A single bout of ergometer cycling induced a significant PEH in healthy volunteers with the expected high inter-individual variability. Targeted lipid spectrum analysis revealed significant upregulation of several lipids in the direct post-exercise phase. Among these changes, only 15- hydroxyeicosatetranoic acid (HETE) correlated significantly with the extent of PEH but in an AA-independent manner, suggesting that 15-HETE might act as specific PEH-marker. Our data indicate that specific lipid modulation might facilitate the identification of patients who will benefit from exercise activity in hypertension therapy. However, larger trials including hypertonic patients are necessary to verify the clinical value of this hypothesis.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Arachidonic Acid; Biological Variation, Population; Blood Pressure; Cross-Over Studies; Dinoprostone; Exercise; Female; Healthy Volunteers; Heart Rate; Humans; Hydroxyeicosatetraenoic Acids; Hypertension; Lipid Metabolism; Male; Pilot Projects; Post-Exercise Hypotension; Thromboxanes

Reactive oxygen species (ROS) contribute to various models of hypertension, including deoxycorticosterone acetate (DOCA)-salt-induced hypertension. Recently, we have shown that ROS, generated by cytochrome P-450 1B1 (CYP1B1) from arachidonic acid, mediate vascular smooth muscle cell growth caused by angiotensin II. This study was conducted to determine the contribution of CYP1B1 to hypertension and associated pathophysiological changes produced by DOCA (30 mg/kg) given subcutaneously per week with 1% NaCl + 0.1% KCl in drinking water to uninephrectomized rats for 6 wk. DOCA-salt treatment increased systolic blood pressure (SBP). Injections of the selective inhibitor of CYP1B1, 2,3',4,5'-tetramethoxystilbene (TMS; 300 μg/kg ip every 3rd day) initiated at the 4th week of DOCA-salt treatment normalized SBP and decreased CYP1B1 activity but not its expression in the aorta, heart, and kidney. TMS also inhibited cardiovascular and kidney hypertrophy, prevented the increase in vascular reactivity and endothelial dysfunction, and minimized the increase in urinary protein and K(+) output and the decrease in urine osmolality, Na(+) output, and creatinine clearance associated with DOCA-salt treatment. These pathophysiological changes caused by DOCA-salt treatment and associated increase in vascular superoxide production, NADPH oxidase activity, and expression of NOX-1, and ERK1/2 and p38 MAPK activities in the aorta, heart, and kidney were inhibited by TMS. These data suggest that CYP1B1 contributes to DOCA-salt-induced hypertension and associated pathophysiological changes, most likely as a result of increased ROS production and ERK1/2 and p38 MAPK activity, and could serve as a novel target for the development of agents like TMS to treat hypertension.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Antihypertensive Agents; Aorta; Aryl Hydrocarbon Hydroxylases; Blood Pressure; Cardiomegaly; Cytochrome P-450 CYP1B1; Desoxycorticosterone; Disease Models, Animal; Diuresis; Endothelium, Vascular; Enzyme Inhibitors; Hydroxyeicosatetraenoic Acids; Hypertension; Kidney; Male; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Muscle, Smooth, Vascular; Myocardium; NADH, NADPH Oxidoreductases; NADPH Oxidase 1; p38 Mitogen-Activated Protein Kinases; Proteinuria; Rats; Rats, Sprague-Dawley; Sodium Chloride, Dietary; Stilbenes; Superoxides; Time Factors; Vasoconstriction; Vasodilation

Arachidonic acid's (AA) metabolites, eicosanoids, exert a tremendous influence on circulatory and vascular homeostasis, and in humans are generated by many organs and cell types. In this study we wanted to verify whether platelets AA metabolism play a significant role in pathogenesis of essential hypertension (EH). Participants were divided into the study (EH) and the control group. Plasma and urine concentrations of isoprostanes (8-iPF(2alpha)-III) and thromboxane B(2) (TxB(2)) were determined using the ELISA method. The levels of 5- and 12-hydroxyeicosatetraenoic (HETE) acids, generated by platelets, were analysed using RP-HPLC. In a suspension of not stimulated and AA-stimulated platelets TxB(2) level was statistically lower in the study than in the control group (p < 0.0001 and 0.001 respectively). The concentration of 12-HETE was significantly elevated in EH patients compared to the control group; however, only in the non-stimulated conditions (p < 0.05). Plasma and urine F2-isoprostanes levels were significantly higher in hypertensive individuals than in the control group (p < 0.00002 and p < 0.01 respectively). Moreover, EH patients excreted more TxB(2) in urine than normotensive individuals (p < 0.05). Our results highlight the mutual connections between the platelets AA metabolism and indicate its possible role in the pathogenesis of arterial hypertension. Moreover, we hypothesize that platelets AA metabolism may exert a pro-atherosclerotic effect. Finally, we suggest the use of (5-HETE+12-HETE)/TxB(2) parameter in further studies.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Arachidonic Acid; Atherosclerosis; Blood Platelets; Case-Control Studies; Humans; Hydroxyeicosatetraenoic Acids; Hypertension; Male; Middle Aged; Thromboxane B2

The arachidonic acid-derived metabolite 12-(S)hydroxyeicosatetraenoic acid (12(S)-HETE), catalyzed by 12-lipoxygenase (12-LOX, ALOX12), exhibits a variety of biological activities with implications in cardiovascular disease. Previous studies have shown higher urinary excretion of this metabolite in essential hypertension. The aim of this study was to analyze the association of polymorphisms in ALOX12 with hypertension and urinary levels of 12(S)-HETE. We studied 200 patients with essential hypertension (aged 56+/-1 years, mean+/-s.e.m., 97 males) and 166 matched controls (aged 54+/-1 years, 91 males). Out of six polymorphisms in the coding region of ALOX12, only R261Q determined a nonconservative amino-acid change and was evaluated by polymerase chain reaction and restriction digestion. Urinary 12(S)-HETE was measured in Sep-Pack-extracted samples using specific enzyme-linked immunosorbent assay. The distribution of genotypes of the R261Q polymorphism was significantly different between patients and controls: patients 92 (0.46) GG, 84 (0.42) GA, 24 (0.12) AA vs controls 56 (0.34) GG, 78 (0.47) GA, 32 (0.19) AA (P=0.030). On the contrary, no association was observed for two intronic polymorphisms. The urinary excretion of 12(S)-HETE (ng/mg creatinine) was significantly higher in GG homozygous patients (13.0+/-1.5) than in GA (8.2+/-1.8) or in AA (8+/-1.5) patients (P=0.018). These results indicate that a nonsynonymous polymorphism in ALOX12 is associated to essential hypertension and to urinary levels of 12(S)-HETE, thus suggesting a role for this gene in this disease.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Aged; Aged, 80 and over; Arachidonate 12-Lipoxygenase; Blood Pressure; Case-Control Studies; Enzyme-Linked Immunosorbent Assay; Exons; Female; Gene Frequency; Genetic Predisposition to Disease; Genetic Variation; Genotype; Humans; Hypertension; Male; Middle Aged; Polymorphism, Genetic

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Arachidonate 12-Lipoxygenase; Arachidonate 15-Lipoxygenase; Blood Pressure; Cardiovascular Diseases; Humans; Hypertension; Leukotrienes; Lipoxygenase; Lipoxygenase Inhibitors

The platelet-type 12-lipoxygenase (12-LO) catalyzes the transformation of arachidonic acid into 12-hydroperoxyeicosatetraenoic acid [12-(S)HPETE], which is reduced to 12-hydroxyeicosatetraenoic acid [12-(S)HETE]. These metabolites exhibit a variety of biological activities such as mediation of angiotensin II-induced intracellular calcium transients in cultured rat vascular smooth muscle cells. It has recently been reported that platelet 12(S)-HETE production is enhanced in the spontaneously hypertensive rat. The pronounced hypotensive effect of LO inhibition in SHR suggests that LO activity may play a role in this form of hypertension. The aim of this study was to determine the basal and thrombin-induced platelet 12(S)-HETE production and the urinary 12(S)-HETE excretion in essential hypertension. We studied 19 patients with this disease (57+/-2 years of age) and 9 normotensive control subjects (48+/-5 years of age) (P:=0.074). 12(S)-HETE was measured in Sep-Pack-extracted samples with specific ELISA and high-performance liquid chromatography. The platelet basal level of 12(S)-HETE was significantly higher in patients than in control subjects (3.56+/-1.22 versus 0.64+/-0.13 ng/10(6) platelets, P:<0.025). In contrast, there were no differences in thrombin-stimulated (1 U/mL) 12(S)-HETE generation: 7.66+/-2.14 in patients versus 4.87+/-1.46 in control subjects (P:=0.61). Platelet 12-LO protein levels, measured by Western blotting with a polyclonal antibody, were higher in the patients than in the control subjects. The urinary excretion of 12(S)-HETE was higher in patients than in control subjects: 36.8+/-7.24 versus 17.1+/-3.14 ng/mg creatinine (P:<0.01). These results indicate that 12(S)-HETE levels and 12-LO protein are increased in patients with essential hypertension, suggesting a role for this metabolite in human hypertension.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adult; Arachidonate 12-Lipoxygenase; Blood Platelets; Chromatography, High Pressure Liquid; Enzyme-Linked Immunosorbent Assay; Female; Humans; Hypertension; Male; Middle Aged

We studied whether 12-hydroxyeicosatetraenoic acid (HETE) affected the angiotensin II-induced pressor response in rats. After intravenous administration of 1 and 3 microg/kg 12-HETE, the angiotensin II-induced pressor response was not potentiated. However, 10, 20 and 30 min after the administration of 10 microg/kg 12-HETE, the angiotensin II-induced pressor responses were increased by 7.5, 6.8 and 4.8 mm Hg, respectively. The significant pressor response was observed at 10 and 20 min after the administration. In this study, we clearly demonstrated that 12-HETE potentiated the angiotensin II-induced pressor response.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Angiotensin II; Animals; Blood Pressure; Hypertension; Male; Rats; Time Factors

This study was designed to examine the contribution of lipoxygenase products to mechanisms of vascular contraction and elevated blood pressure in rats with aortic coarctation-induced hypertension. In cytosolic fractions of aortae taken from hypertensive rats, 12-lipoxygenase protein was increased as compared to normotensive controls. Aortic rings from hypertensive, but not from normotensive rats, exhibited a basal tone which was reduced 74+/-12 and 71+/-22%, respectively, by the lipoxygenase inhibitors cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate (CDC, 10(-5) mol/L) and 5,8,11-eicosatriynoic acid (ETI, 10(-5) mol/L). CDC (8 mg/kg s.c.) did not affect the blood pressure of normotensive rats but decreased that of hypertensive rats from 182+/-6 to 151+/-10 mm Hg. The blood pressure lowering effect of CDC was blunted in hypertensive rats pretreated with indomethacin or antibodies against 5,6-dihydro-prostaglandin I2. These data suggest contribution of lipoxygenase-derived products to mechanisms underlying aortic smooth muscle basal tone and elevated blood pressure in rats with aortic coarctation-induced hypertension. The vasodepressor effect of CDC depends on a mechanism involving vasodilatory prostaglandins.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; 8,11,14-Eicosatrienoic Acid; Animals; Aorta, Thoracic; Blood Pressure; Caffeic Acids; Cyclooxygenase Inhibitors; Disease Models, Animal; Epoprostenol; Hypertension; Indomethacin; Leukotrienes; Lipoxygenase; Lipoxygenase Inhibitors; Male; Muscle, Smooth, Vascular; Prostaglandins, Synthetic; Rats; Rats, Sprague-Dawley; Vasoconstriction; Vasoconstrictor Agents

We have previously demonstrated that administration of inhibitors of the lipoxygenase (LO) pathway of arachidonic acid metabolism lowers blood pressure in hypertensive rats. In addition, we have shown that LO inhibition attenuates pressor agonist-induced vascular reactivity in vitro and calcium mobilization in cultured vascular smooth muscle cells (VSMC). To further elucidate the relationship between elevated LO activity and hypertension, 4, 8, and 12 week old hypertensive SHR were compared with age-matched Wistar-Kyoto (WKY) rats for plasma 12(S)-hydroxyeicosatetraenoic acid (12-HETE) concentration. 12-HETE levels were significantly elevated in the SHR compared to the WKY (SHR elevated by 154%, 159%, and 272% compared to WKY at 4, 8, and 12 weeks, respectively, P < .01 for all ages). There were no differences in plasma potassium levels between SHR and WKY at any of the ages tested. Plasma aldosterone levels and plasma renin activity were in the normal range at the three ages. At 12 weeks of age, both serum (4.72 +/- 0.23 v 2.18 +/- 0.33 microg/mL, P < .01), and aortic smooth muscle 12-HETE levels (0.94 +/- 0.09 v 0.66 +/- 0.08 microg/mg protein, P < .05) were elevated in SHR compared with WKY. The 12 week old SHR were given a bolus of the LO inhibitor 5,8,11-eicosatriynoic acid (ETI, 7 mg/kg, intravenously) and blood pressure measured after 20 min. ETI reduced mean systolic blood pressure from 175.8 +/- 4.2 to 141.6 +/- 5.9 mm Hg (P < .05). To investigate these effects of HETEs, cultured vascular smooth muscle cells were pretreated for 1 min with 12(S)HETE and then challenged with angiotensin II (AngII). The addition of 12(S)HETE increased AngII-induced intracellular calcium levels in normal cultured rat vascular smooth muscle cells by 78% compared to vehicle (P < .05). Thus, LO products, which are high in SHR, may contribute to vascular tone through alterations in the intracellular calcium signal by potentiating calcium responses to pressors such as Ang II.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Aging; Animals; Arachidonate 12-Lipoxygenase; Calcium; Cells, Cultured; Hypertension; Male; Muscle, Smooth, Vascular; Rats; Rats, Inbred SHR; Rats, Inbred WKY

We have previously reported that the nonselective lipoxygenase inhibitor phenidone is a potent hypotensive agent in the spontaneously hypertensive rat (SHR). In the present study, we examined the relationship between production of platelet 12-hydroxyeicosatetraenoic acid (12-HETE) and intra-arterial blood pressure in SHR and Wistar-Kyoto rats (WKY) using both a cross-sectional analysis and an acute pharmacological intervention. Basal generation rate of 12-HETE by platelets collected from the SHR was approximately 3.7-fold higher than in the WKY (0.86 +/- 0.24 versus 0.23 +/- 0.05 nmol/mL per 10 minutes, respectively; P < .01). Systolic arterial pressure was positively related to platelet 12-HETE formation rate when the entire rat population was considered (r = .70, P < .001). The specific 12-lipoxygenase inhibitor cinnamyl-3,4-dihydroxycyanocinnamate induced lowering of both arterial blood pressure and platelet 12-lipoxygenase activity in SHR. At 15 mg/kg, cinnamyl-3,4-dihydroxycyanocinnamate elicited a marked hypotensive effect in SHR but not in WKY. This reduction in arterial pressure was accompanied by an approximate 70% inhibition in platelet 12-HETE production rate. The return of high blood pressure to basal levels was associated with a significant rise in the production of platelet 12-HETE toward control values (baseline, 0.97 +/- 0.33 nmol/mL per 10 minutes; nadir of blood pressure, 0.19 +/- 0.03; resumption of basal pressure, 0.42 +/- 0.14). In contrast, captopril (15 mg/kg) induced a quantitatively similar decrease in blood pressure but had no effect on platelet 12-HETE generation rate. Thus, hypertension in SHR is linked to increased production rate of platelet 12-HETE. Acute blood pressure reduction attained during lipoxygenase inhibition but not by angiotensin converting enzyme inhibition leads to a concomitant reduction in the production of platelet 12-HETE. We speculate that since rat arterial tissue produces 12-HETE, increased 12-lipoxygenase activity in SHR may contribute to the maintenance of elevated arterial pressure in this strain.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Blood Platelets; Blood Pressure; Caffeic Acids; Cross-Sectional Studies; Hydroxyeicosatetraenoic Acids; Hypertension; Lipoxygenase; Lipoxygenase Inhibitors; Male; Rats; Rats, Inbred SHR; Rats, Inbred WKY

The important role of eicosanoids in pregnancy-induced hypertension is generally accepted. Because of the lack of innervation of the uteroplacental vessels, humoral vasoactive factors are important for the regulation of vascular tone. Until now, mainly the balance of vasodilatative and vasoconstrictive prostaglandins has been studied. We were able to confirm their intrauterine imbalance in hypertensive pregnancies. In addition, the placental production of less known lipoxygenase metabolites has been analyzed in this study. Intrauterine tissues (30-100mg wet weight) were examined for their release of eicosanoids. Short term tissue cultures were performed in Hanks balanced salts solution (HBSS) at 37 degrees C in an atmosphere of 95% air/5% CO2 with and without incorporation of tritiated arachidonic acid. The arachidonate metabolites in culture media were analyzed by High Performance Liquid Chromatography (HPLC) with radioactivity detection or by enzyme immunoassays or radioimmunoassays, respectively. All intrauterine tissues released more lipoxygenase metabolites than cyclooxygenase metabolites with 12-hydroxy-eicosatetraenic acid (12-HETE) as their main metabolite. The placental release of 12-HETE was significantly decreased in hypertensive pregnancies. In hypertensive pregnancies the ratio TXB2/6-keto-PGF1 alpha synthesis was increased. Lipoxygenase metabolites, especially 12-HETE, seem to have important physiological and pathophysiological functions in the intrauterine compartment. Their biological role in this context needs further investigation.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Chromatography, High Pressure Liquid; Eicosanoids; Female; HELLP Syndrome; Humans; Hydroxyeicosatetraenoic Acids; Hypertension; Placenta; Pre-Eclampsia; Pregnancy; Pregnancy Complications, Cardiovascular; Uterus

The lipoxygenase pathway of arachidonate cascade in the platelets of spontaneously hypertensive rats has been found to be significantly higher than in normotensive animals. Repeated oral administration of Captopril (in drinking water - 200 mg/100 ml) for 14 days resulted in an elevation in the activity of arachidonate cascade in the platelets of treated rats. At the same time the Captopril treatment induced the formation of 12-hydroxy-heptadecatrienoic acid (12-HHT), which molecule is known to be a potent prostacyclin (PGI2) releaser and/or synthesis inducer. PGI2 is one of the most potent vasodilatator molecule in living organisms. The in vitro experiments in rat platelets suggest, that very low doses of Captopril (10(-12) to 10(-10) M) result in a significantly elevated 12-HHT synthesis. Captopril might act through the 12-HHT--PGI2 mechanism, resulting in blood pressure reduction. The lipoxygenase pathway of platelets, the formation of 12-hydroxyeicosatetraenoic acid (12-HETE), was significantly elevated in vitro in the presence of low dose of Captopril (10(-11) and 10(-10) M).

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Arachidonic Acids; Blood Platelets; Captopril; Dose-Response Relationship, Drug; Epoprostenol; Fatty Acids, Unsaturated; Female; Hydroxyeicosatetraenoic Acids; Hypertension; In Vitro Techniques; Male; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Rats, Wistar; Reference Values