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Vu TT, Dieterich P, Vu TT, Deussen A. Docosahexaenoic acid reduces adenosine triphosphate-induced calcium influx via inhibition of store-operated calcium channels and enhances baseline endothelial nitric oxide synthase phosphorylation in human endothelial cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2019; 23:345-356. [PMID: 31496872 PMCID: PMC6717795 DOI: 10.4196/kjpp.2019.23.5.345] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 12/25/2022]
Abstract
Docosahexaenoic acid (DHA), an omega-3-fatty acid, modulates multiple cellular functions. In this study, we addressed the effects of DHA on human umbilical vein endothelial cell calcium transient and endothelial nitric oxide synthase (eNOS) phosphorylation under control and adenosine triphosphate (ATP, 100 µM) stimulated conditions. Cells were treated for 48 h with DHA concentrations from 3 to 50 µM. Calcium transient was measured using the fluorescent dye Fura-2-AM and eNOS phosphorylation was addressed by western blot. DHA dose-dependently reduced the ATP stimulated Ca2+-transient. This effect was preserved in the presence of BAPTA (10 and 20 µM) which chelated the intracellular calcium, but eliminated after withdrawal of extracellular calcium, application of 2-aminoethoxy-diphenylborane (75 µM) to inhibit store-operated calcium channel or thapsigargin (2 µM) to delete calcium store. In addition, DHA (12 µM) increased ser1177/thr495 phosphorylation of eNOS under baseline conditions but had no significant effect on this ratio under conditions of ATP stimulation. In conclusion, DHA dose-dependently inhibited the ATP-induced calcium transient, probably via store-operated calcium channels. Furthermore, DHA changed eNOS phosphorylation suggesting activation of the enzyme. Hence, DHA may shift the regulation of eNOS away from a Ca2+ activated mode to a preferentially controlled phosphorylation mode.
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Affiliation(s)
- Thom Thi Vu
- Department of Physiology, Medical Faculty Carl Gustav Carus, Technical University Dresden, Dresden 01307, Germany.,Department of Basic Sciences in Medicine and Pharmacy, School of Medicine and Pharmacy, Vietnam National University, Hanoi 100000, Vietnam
| | - Peter Dieterich
- Department of Physiology, Medical Faculty Carl Gustav Carus, Technical University Dresden, Dresden 01307, Germany
| | - Thu Thi Vu
- Faculty of Biology, VNU University of Science, Hanoi 100000, Vietnam.,Dinh Tien Hoang Institute of Medicine, Hanoi 100000, Vietnam
| | - Andreas Deussen
- Department of Physiology, Medical Faculty Carl Gustav Carus, Technical University Dresden, Dresden 01307, Germany
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Machida T, Yutani M, Goto A, Nishimura S, Kawamura A, Iizuka K, Hirafuji M. Docosahexaenoic acid suppresses angiotensin II-induced A7r5 vascular smooth muscle cell proliferation and migration under pulsatile pressure stress. Biomed Res 2018; 39:141-148. [PMID: 29899189 DOI: 10.2220/biomedres.39.141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Elevated mechanical stress applied to vascular walls is well known to modulate vascular remodeling and plays a part in the pathogenesis of atherosclerosis. On the other hand, docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid, has been shown to protect against several types of cardiovascular diseases including atherosclerosis and hypertension. The aim of this study was to clarify the effect of pulsatile pressure stress and DHA on angiotensin II-induced proliferation and migration in A7r5 vascular smooth muscle cells (VSMCs). Pulsatile pressure of between 80 and 160 mmHg was repeatedly applied to VSMCs at a frequency of 4 cycles per min using an apparatus that we developed. Cell proliferation and migration were evaluated using a live cell movie analyzer. Application of pulsatile pressure stress for 24 h significantly increased cell proliferation. Angiotensin II also significantly increased cell proliferation in the presence or absence of pressure stress. DHA significantly inhibited angiotensin II-induced cell proliferation regardless of the pressure load. Angiotensin II significantly induced cell migration regardless of the pulsatile pressure load. Pulsatile pressure stress alone slightly, but not significantly, induced cell migration. DHA inhibited angiotensin II-induced VSMC proliferation and migration under abnormal pressure conditions. Pressure stress tended to induce extracellular signal-regulated kinase (ERK) phosphorylation in the absence of angiotensin II, whereas it significantly induced ERK phosphorylation in the presence of angiotensin II. However, the pressure-induced ERK phosphorylation was not observed in the DHA-treated VSMCs. Our findings may contribute to the understanding of the beneficial effect of DHA on various cardiovascular disorders.
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Machida T. Analysis of Vascular Cell Response to Hypertension Induced by Pressure Loading and Its Application as a Tool for Exploring Pharmacological Modes of Action. YAKUGAKU ZASSHI 2017; 136:1485-1490. [PMID: 27803479 DOI: 10.1248/yakushi.16-00188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression is induced by interleukin-1β (IL-1β) stimulation in vascular smooth muscle cells (VSMCs), resulting in the production of nitric oxide and prostaglandins such as PGI2. The expression of iNOS and COX-2 in cultured VSMCs isolated from 6-7-week-old stroke-prone spontaneously hypertensive rats (SHRSP) is significantly lower than in cells of normotensive Wistar Kyoto rats (WKY). These reductions are also found in cells exposed to pulsatile atmospheric pressure between 80-160 mmHg at a rate of 4 cycles/min, which simulates systolic hypertension. Docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid, potentiates IL-1β-induced iNOS and COX-2 expression in VSMCs isolated from WKY, but not those from SHRSP. In response to endothelial injury at a local site, iNOS and COX-2 induction in VSMCs may function primarily as a defensive and compensatory mechanism for endothelial dysfunction by preventing the development of pathological conditions. Thus, in certain pathological conditions associated with hypertension, vascular walls with reduced iNOS and COX-2 expression may aggravate or initiate further vascular injury. In this situation, DHA may contribute to maintaining homeostasis in VSMCs by potentiating iNOS and COX-2 expression. Using cells isolated from a genetic pathological animal model alongside cells exposed to experimental pathological conditions can be an effective tool for the analysis of cell response to hypertension and exploring pharmacological modes of action in vitro.
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Affiliation(s)
- Takuji Machida
- Department of Pharmacological Sciences, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido
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Elinder F, Liin SI. Actions and Mechanisms of Polyunsaturated Fatty Acids on Voltage-Gated Ion Channels. Front Physiol 2017; 8:43. [PMID: 28220076 PMCID: PMC5292575 DOI: 10.3389/fphys.2017.00043] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 01/16/2017] [Indexed: 01/29/2023] Open
Abstract
Polyunsaturated fatty acids (PUFAs) act on most ion channels, thereby having significant physiological and pharmacological effects. In this review we summarize data from numerous PUFAs on voltage-gated ion channels containing one or several voltage-sensor domains, such as voltage-gated sodium (NaV), potassium (KV), calcium (CaV), and proton (HV) channels, as well as calcium-activated potassium (KCa), and transient receptor potential (TRP) channels. Some effects of fatty acids appear to be channel specific, whereas others seem to be more general. Common features for the fatty acids to act on the ion channels are at least two double bonds in cis geometry and a charged carboxyl group. In total we identify and label five different sites for the PUFAs. PUFA site 1: The intracellular cavity. Binding of PUFA reduces the current, sometimes as a time-dependent block, inducing an apparent inactivation. PUFA site 2: The extracellular entrance to the pore. Binding leads to a block of the channel. PUFA site 3: The intracellular gate. Binding to this site can bend the gate open and increase the current. PUFA site 4: The interface between the extracellular leaflet of the lipid bilayer and the voltage-sensor domain. Binding to this site leads to an opening of the channel via an electrostatic attraction between the negatively charged PUFA and the positively charged voltage sensor. PUFA site 5: The interface between the extracellular leaflet of the lipid bilayer and the pore domain. Binding to this site affects slow inactivation. This mapping of functional PUFA sites can form the basis for physiological and pharmacological modifications of voltage-gated ion channels.
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Affiliation(s)
- Fredrik Elinder
- Department of Clinical and Experimental Medicine, Linköping University Linköping, Sweden
| | - Sara I Liin
- Department of Clinical and Experimental Medicine, Linköping University Linköping, Sweden
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Machida T, Onoguchi A, Iizuka K, Ishibashi S, Yutani M, Hirafuji M. Effect of Docosahexaenoic Acid on Voltage-Independent Ca 2+ Entry Pathways in Cultured Vascular Smooth Muscle Cells Stimulated with 5-Hydroxytryptamine. Biol Pharm Bull 2017; 40:916-921. [DOI: 10.1248/bpb.b16-00788] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Takuji Machida
- Department of Pharmacological Sciences, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido
| | - Akina Onoguchi
- Department of Pharmacological Sciences, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido
| | - Kenji Iizuka
- Department of Pharmacological Sciences, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido
| | - Sayuri Ishibashi
- Department of Pharmacological Sciences, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido
| | - Mikiko Yutani
- Department of Pharmacological Sciences, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido
| | - Masahiko Hirafuji
- Department of Pharmacological Sciences, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido
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Shantakumari N, Eldeeb RA, Ibrahim SAM, Sreedharan J, Otoum S. Effect of PUFA on patients with hypertension: a hospital based study. Indian Heart J 2014; 66:408-14. [PMID: 25173198 DOI: 10.1016/j.ihj.2014.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 01/23/2014] [Accepted: 05/13/2014] [Indexed: 11/16/2022] Open
Abstract
INTRODUCTION Hypertension affects more than a quarter of the global adult population. Studies conducted worldwide suggest an overall small, yet useful, role of omega-3 PUFAs in reducing blood pressure in hypertensive patients. However there is no substantial data in this regard from population based in Middle East and Asia. OBJECTIVES To determine the effects of (omega-3) PUFA supplementation on the blood pressure of hypertensive patient. To identify if male and female hypertensive patients respond differently to PUFA. To identify if response of hypertensive patients to PUFA varies with the duration of hypertension and co-existence of diabetes/dyslipidemia. MATERIALS AND METHODS This observational study was conducted among hypertensive patients visiting OPD of the Gulf Medical College Hospital, Ajman, UAE, during the period Jan-Dec 2012. A total of 100 hypertensive patients on treatment with their antihypertensive medications, 50 of whom were taking n-3 PUFA supplementation, were followed up for a period of 3 months. Comparisons were drawn between the BP recordings at the time of enrollment in the study and their follow up values 3 months after enrollment. RESULTS There was a statistically significant reduction in both the systolic and diastolic blood pressures after 3 months of PUFA therapy. The BP lowering effect of PUFA was more in males. A statistically significant reduction in BP was noted in non-diabetic patients and patients with long standing hypertension. CONCLUSION Findings of the study suggest that omega-3 PUFA dietary supplements augment the benefits of pharmacotherapy in hypertension.
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Affiliation(s)
- Nisha Shantakumari
- Asst. Professor, Department of Physiology, Gulf Medical University, Ajman, P.O. Box: 4184, United Arab Emirates.
| | - Rasha Ali Eldeeb
- Asst. Professor, Department of Physiology, Gulf Medical University, Ajman, P.O. Box: 4184, United Arab Emirates
| | | | | | - Sufian Otoum
- College of Pharmacy, Gulf Medical University, Ajman, United Arab Emirates
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Fujii K, Machida T, Iizuka K, Hirafuji M. Sphingosine 1-phosphate increases an intracellular Ca(2+) concentration via S1P3 receptor in cultured vascular smooth muscle cells. J Pharm Pharmacol 2014; 66:802-10. [PMID: 24450400 DOI: 10.1111/jphp.12214] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 12/07/2013] [Indexed: 12/29/2022]
Abstract
OBJECTIVE We investigated the effect of sphingosine 1-phosphate (S1P) on intracellular Ca(2+) dynamics in rat vascular smooth muscle cells (VSMCs). METHODS Intracellular Ca(2+) concentration ([Ca(2+) ]i) was determined using a fluorescence dye fura-2/AM. Small interfering RNAs (siRNA) were transfected into VSMCs to deplete the expression of S1P2 and S1P3 receptors. KEY FINDINGS S1P induced a rapid and transient elevation in [Ca(2+) ]i, which was maximal 1 min after the stimulation, followed by a sustained increase. When extracellular Ca(2+) was removed, a decrease in resting level and a small and transient increase in [Ca(2+) ]i by S1P stimulation were observed. siRNA targeted for the S1P3 receptor almost completely inhibited the S1P-induced increase in [Ca(2+) ]i. The rapid and transient increase in [Ca(2+) ]i was significantly inhibited by diltiazem at a high concentration. Pertussis toxin and a phospholipase C (PLC) inhibitor inhibited the S1P-induced increase in [Ca(2+) ]i regardless of the presence of extracellular Ca(2+) . Furthermore, S1P activated store-operated and receptor-operated Ca(2+) entry. CONCLUSIONS These results suggest that S1P increases [Ca(2+) ]i via the S1P3 receptor by inducing an influx of extracellular Ca(2+) partially through the voltage-dependent Ca(2+) channels, as well as by mobilizing Ca(2+) from its intracellular stores. S1P3 receptor-coupled Gi/o protein and PLC activation mediate the mechanisms.
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Affiliation(s)
- Kazumi Fujii
- Department of Pharmacological Sciences, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan
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Sun T, Wang J, Huang LH, Cao YX. Antihypertensive effect of formononetin through regulating the expressions of eNOS, 5-HT2A/1B receptors and α1-adrenoceptors in spontaneously rat arteries. Eur J Pharmacol 2012; 699:241-9. [PMID: 23123056 DOI: 10.1016/j.ejphar.2012.10.031] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 09/29/2012] [Accepted: 10/13/2012] [Indexed: 11/15/2022]
Abstract
One of the main pathological changes of hypertension is the dysfunction of blood vessels. We have found in our previous study that formononetin, one kind of phytoestrogens, has an acute antihypertensive effect. Therefore, we hypothesized that formononetin might produce a chronic antihypertensive effect through regulating the expressions of contractile receptors and endothelial nitric oxide synthase (eNOS) in artery. The present study was conducted to verify this effect. Male spontaneously hypertensive rats (SHRs) were divided into two groups, orally administrated formononetin (50mg/kg per day) and Tween 80 vehicle, respectively, for 8 weeks. The blood pressure was measured by tail-cuff method. Isometric tension of arterial rings was recorded by a myograph system. The mRNA and protein expression in arteries was determined with quantitative real-time polymerase chain reaction and immunohistochemistry, respectively. Results showed that the systolic blood pressure of SHRs decreased significantly in formononetin group compared to Tween 80 group. The vasoconstriction induced by phenylephrine or 5-hydroxytryptamine (5-HT) in the mesenteric artery segments in formononetin group was decreased, and the relaxation induced by acetylcholine was increased compared with that in Tween 80 group. In the mesenteric arteries of the formononetin-treated SHRs, the expressions of α(1)-adrenoceptors and 5-HT(2A/1B) receptors at both mRNA and protein levels decreased, while the mRNA and protein expressions of eNOS increased. In conclusion, formononetin has a chronic antihypertensive effect in SHRs. The antihypertensive mechanism may be associated with the down-regulation of α(1)-adrenoceptors and 5-HT(2A/1B) receptors, and the up-regulation of eNOS expression in arteries.
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Affiliation(s)
- Tao Sun
- Department of Pharmacology, Xi'an Jiaotong University College of Medicine, 76 Yanta West Road, Xi'an, Shaanxi 710061, PR China
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Vanhorn J, Altenburg JD, Harvey KA, Xu Z, Kovacs RJ, Siddiqui RA. Attenuation of niacin-induced prostaglandin D(2) generation by omega-3 fatty acids in THP-1 macrophages and Langerhans dendritic cells. J Inflamm Res 2012; 5:37-50. [PMID: 22442634 PMCID: PMC3308705 DOI: 10.2147/jir.s29044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Niacin, also known as nicotinic acid, is an organic compound that has several cardio-beneficial effects. However, its use is limited due to the induction of a variable flushing response in most individuals. Flushing occurs from a niacin receptor mediated generation of prostaglandins from arachidonic acid metabolism. This study examined the ability of docosahexaenoic acid, eicosapentaenoic acid, and omega-3 polyunsaturated fatty acids (PUFAs), to attenuate niacin-induced prostaglandins in THP-1 macrophages. Niacin induced both PGD2 and PGE2 generation in a dose-dependent manner. Niacin also caused an increase in cytosolic calcium and activation of cytosolic phospholipase A2. The increase in PGD2 and PGE2 was reduced by both docosahexaenoic acid and eicosapentaenoic acid, but not by oleic acid. Omega-3 PUFAs efficiently incorporated into cellular phospholipids at the expense of arachidonic acid, whereas oleic acid incorporated to a higher extent but had no effect on arachidonic acid levels. Omega-3 PUFAs also reduced surface expression of GPR109A, a human niacin receptor. Furthermore, omega-3 PUFAs also inhibited the niacin-induced increase in cytosolic calcium. Niacin and/or omega-3 PUFAs minimally affected cyclooxygenase-1 activity and had no effect on cyclooxygenase -2 activity. The effects of niacin on PGD2 generation were further confirmed using Langerhans dendritic cells. Results of the present study indicate that omega-3 PUFAs reduced niacin-induced prostaglandins formation by diminishing the availability of their substrate, as well as reducing the surface expression of niacin receptors. In conclusion, this study suggests that the regular use of omega-3 PUFAs along with niacin can potentially reduce the niacin-induced flushing response in sensitive patients.
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Affiliation(s)
- Justin Vanhorn
- Cellular Biochemistry Laboratory, Methodist Research Institute, Indianapolis
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SUN T, LIU R, CAO YX. Vasorelaxant and antihypertensive effects of formononetin through endothelium-dependent and -independent mechanisms. Acta Pharmacol Sin 2011; 32:1009-18. [PMID: 21818108 DOI: 10.1038/aps.2011.51] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIM To investigate the mechanisms underlying the vasorelaxant effect of formononetin, an O-methylated isoflavone, in isolated arteries, and its antihypertensive activity in vivo. METHODS Arterial rings of superior mesenteric arteries, renal arteries, cerebral basilar arteries, coronary arteries and abdominal aortas were prepared from SD rats. Isometric tension of the arterial rings was recorded using a myograph system. Arterial pressure was measured using tail-cuff method in spontaneously hypertensive rats. RESULTS Formononetin (1-300 μmol/L) elicited relaxation in arteries of the five regions that were pre-contracted by KCl (60 mmol/L), U46619 (1 μmol/L) or phenylephrine (10 μmol/L). The formononetin-induced relaxation was reduced by removal of endothelium or by pretreatment with L-NAME (100 μmol/L). Under conditions of endothelium denudation, formononetin (10, 30, and 100 μmol/L) inhibited the contraction induced by KCl and that induced by CaCl(2) in Ca(2+)-free depolarized medium. In the absence of extracellular Ca(2+), formononetin (10, 30, and 100 μmol/L) depressed the constriction caused by phenylephrine (10 μmol/L), but did not inhibit the tonic contraction in response to the addition of CaCl(2) (2 mmol/L). The contraction caused by caffeine (30 mmol/L) was not inhibited by formononetin (100 μmol/L). Formononetin (10 and 100 μmol/L) reduced the change rate of Ca(2+)-fluorescence intensity in response to KCl (50 mmol/L). In spontaneously hypertensive rats, formononetin (5, 10, and 20 mg/kg) slowly lowered the systolic, diastolic and mean arterial pressure. CONCLUSION Formononetin causes vasodilatation via two pathways: (1) endothelium-independent pathway, probably due to inhibition of voltage-dependent Ca(2+) channels and intracellular Ca(2+) release; and (2) endothelium-dependent pathway by releasing NO. Both the pathways may contribute to its antihypertensive effect.
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Adkins Y, Kelley DS. Mechanisms underlying the cardioprotective effects of omega-3 polyunsaturated fatty acids. J Nutr Biochem 2010; 21:781-92. [DOI: 10.1016/j.jnutbio.2009.12.004] [Citation(s) in RCA: 362] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 12/01/2009] [Accepted: 12/03/2009] [Indexed: 12/11/2022]
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Ye S, Tan L, Ma J, Shi Q, Li J. Polyunsaturated docosahexaenoic acid suppresses oxidative stress induced endothelial cell calcium influx by altering lipid composition in membrane caveolar rafts. Prostaglandins Leukot Essent Fatty Acids 2010; 83:37-43. [PMID: 20206488 DOI: 10.1016/j.plefa.2010.02.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2009] [Revised: 01/22/2010] [Accepted: 02/02/2010] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To determine whether DHA suppresses oxidative stress induced endothelial cell calcium influx by altering lipid composition and TRPC1 distribution in membrane rafts. METHODS Endothelial cells (EC) were pretreated with DHA or stearic acid, then incubated for another 3h with media containing H(2)O(2). Membrane lipid rafts were isolated using the discontinuous sucrose density gradient ultracentrifugation method. Intracellular calcium was detected with laser scanning confocal microscope. TRPC1 protein in membrane fractions was detected by immunoblotting. Membrane fatty acids compositions were analyzed by gas chromatography; raft cholesterol level was assayed by an Amplex Red Cholesterol Assay kit, and DAG concentration was quantified by a DAG kinase assay. RESULTS DHA significantly reduced oxidative stress induced calcium influx; pretreated with DHA the n-3 PUFAs were significantly increased in raft fractions, as well as saturated myristic acid, palmitic acid content of membrane rafts in EC; while the stearic acid, monounsaturated oleic acid and cis-oleic acid were decreased. Incubation with DHA also significantly reduced the amount of SM and cholesterol levels in the raft. Interestingly, we fractioned plasma membrane subcellular compartments and discovered that certain amounts of TRPC1 existed in detergent-resistant plasma membrane fractions of EC. After DHA treatment, TRPC1 was partly displaced from lipid raft to detergent-soluble membrane fractions. CONCLUSIONS DHA significantly reduces oxidative stress induced endothelial calcium influx, this effect might be associated with, at least in part, altered raft lipid environment, and suppresses TRPC1-mediated calcium signaling pathway by partially displacing TRPC1 from membrane caveolar lipid rafts.
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Affiliation(s)
- Sheng Ye
- Institute of Hepatobiliary Surgery, Chinese PLA General Hospital, Beijing 100853, China.
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Siddiqui RA, Harvey KA, Zaloga GP. Modulation of enzymatic activities by n-3 polyunsaturated fatty acids to support cardiovascular health. J Nutr Biochem 2008; 19:417-37. [PMID: 17904342 DOI: 10.1016/j.jnutbio.2007.07.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Revised: 06/14/2007] [Accepted: 07/03/2007] [Indexed: 12/13/2022]
Abstract
Epidemiological evidence from Greenland Eskimos and Japanese fishing villages suggests that eating fish oil and marine animals can prevent coronary heart disease. Dietary studies from various laboratories have similarly indicated that regular fish oil intake affects several humoral and cellular factors involved in atherogenesis and may prevent atherosclerosis, arrhythmia, thrombosis, cardiac hypertrophy and sudden cardiac death. The beneficial effects of fish oil are attributed to their n-3 polyunsaturated fatty acid (PUFA; also known as omega-3 fatty acids) content, particularly eicosapentaenoic acid (EPA; 20:5, n-3) and docosahexaenoic acid (DHA; 22:6, n-3). Dietary supplementation of DHA and EPA influences the fatty acid composition of plasma phospholipids that, in turn, may affect cardiac cell functions in vivo. Recent studies have demonstrated that long-chain omega-3 fatty acids may exert beneficial effects by affecting a wide variety of cellular signaling mechanisms. Pathways involved in calcium homeostasis in the heart may be of particular importance. L-type calcium channels, the Na+-Ca2+ exchanger and mobilization of calcium from intracellular stores are the most obvious key signaling pathways affecting the cardiovascular system; however, recent studies now suggest that other signaling pathways involving activation of phospholipases, synthesis of eicosanoids, regulation of receptor-associated enzymes and protein kinases also play very important roles in mediating n-3 PUFA effects on cardiovascular health. This review is therefore focused on the molecular targets and signaling pathways that are regulated by n-3 PUFAs in relation to their cardioprotective effects.
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Affiliation(s)
- Rafat A Siddiqui
- Cellular Biochemistry Laboratory, Methodist Research Institute, Clarian Health, Indianapolis, IN 46202, USA.
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Conde CMS, Cyrino FZGA, Bottino DA, Gardette J, Bouskela E. Longchain n-3 polyunsaturated fatty acids and microvascular reactivity: Observation in the hamster cheek pouch. Microvasc Res 2007; 73:237-47. [PMID: 17196224 DOI: 10.1016/j.mvr.2006.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 11/10/2006] [Accepted: 11/14/2006] [Indexed: 10/01/2022]
Abstract
Previous experiments in our laboratory, using the hamster cheek pouch microcirculation, have shown that precapillary vessels exhibit spontaneous rhythmic luminal variations, termed vasomotion, a myogenic activity sustained by a balance between membrane currents among which polarizing K(+) currents play an important role. In these microvessels, endothelium-derived relaxing factors (EDRFs) seem to regulate arteriolar diameter [via nitric oxide (NO) and cyclic GMP] and vasomotion [probably via endothelium-derived hyperpolarizing factor (EDHF)]. Fish or fish oil diet can decrease the risk of cardiovascular diseases, probably by modifying the conductance of selective ion channels, such as K(+) and/or Ca(++), and/or increasing the production of vasodilators, such as NO. To investigate its effect on microvascular reactivity, using the same preparation and an intravital microscope coupled to a closed circuit TV system, male hamsters were treated for 14 days, twice a day, with 0.4 mL/100 g body weight with fish or olive oil. An attempt was also undertaken to record in arterioles, in vivo, the membrane potential of smooth muscle cells during their vasomotor activity combining conventional microelectrode and intravital microscopy techniques. The effects of topical application of two vasodilators, acetylcholine [endothelium-dependent one, NO release and membrane hyperpolarization via Ca(++)-activated K(+) channels (K(Ca))] and sodium nitroprusside (endothelium-independent, NO donor and no change on membrane potential) and two vasoconstrictors which elicited membrane depolarization via Ca(++) channels, phenylephrine (alpha(1)-adrenergic receptor agonist) and serotonin (5-hydroxi-tryptamine) on mean internal diameter of arterioles and venules, arteriolar blood flows, spontaneous arteriolar vasomotion frequency and amplitude and functional capillary density (FCD, number of capillaries with flowing red blood cells per unit area of tissue) were determined. Anesthesia was induced by sodium pentobarbital (i.p.) and maintained with alpha-chloralose through the femoral vein. In the presence of vasomotion, the membrane potentials are slowly oscillating by about 20 mV around values of approximately -50 mV in perfect synchrony with vasomotor movements and depolarizing phases coincide with vasoconstrictions while polarizing ones with vasodilatations. Comparing all parameters, in control conditions, only the spontaneous vasomotion frequency was significantly higher (2.37 times higher) on the group treated with fish oil and persisted as such throughout all experiments. With topical application of the drugs mentioned above, the group treated with fish oil showed, for each drug concentration, a balance towards vasodilatation with consequent increase on arteriolar blood flow and on FCD, compared with the olive oil treated one. No significant changes on mean arterial pressure, spontaneous arteriolar vasomotion amplitude or venular diameter could be detected in the two groups. Our results support the concept that, in the hamster cheek pouch microcirculation, fish oil supplementation activates K(+) channels which act as the EDHF and might also increase the production of vasodilators, probably NO.
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Affiliation(s)
- Cristiane M S Conde
- Laboratório de Pesquisas em Microcirculação, Pavilhão Reitor Haroldo Lisboa da Cunha, térreo, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, 20550-013 Rio de Janeiro RJ, Brazil
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15
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Xu L, Yu BP, Chen JG, Luo HS. Mechanisms mediating serotonin-induced contraction of colonic myocytes. Clin Exp Pharmacol Physiol 2007; 34:120-8. [PMID: 17201746 DOI: 10.1111/j.1440-1681.2007.04465.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
1. 5-Hydroxytryptamine (5-HT) has an important role in the pathogenesis of irritable bowel syndrome. To investigate the effects of 5-HT on the contractile activity of myocytes of the guinea-pig proximal colon, cell imaging before and after contraction was undertaken and images were analysed using image-analysis software. Ion currents and membrane potentials were measured. Cytoplasmic free Ca(2+) was recorded using a confocal microscope following loading of the cells with the fluorescent probe Fura-2AM. 2. 5-Hydroxytryptamine reduced cell length in a dose-dependent manner (EC(50) = 0.189 micromol/L). Under current clamp, 10 micromol/L 5-HT reduced action potential amplitude (measured as peak height) and decreased action potential duration, as well as depolarizing the resting potential from -68.4 +/- 3.6 to -22.96 +/- 4.65 mV. Iberiotoxin (1 micromol/L) blocked the effects of 5-HT in reducing the time to repolarization (T(90)) and nicardipine (5 micromol/L) blocked the effects of 5-HT in reducing action potential amplitude. 3. In the whole-cell mode, 5-HT enhanced L-type Ca(2+) currents, large conductance K(+) channel (BK(Ca)) currents and spontaneous transient outward currents (STOC). In addition, 5-HT increased intracellular Ca(2+) levels. Ondansetron (10 micromol/L) blocked the effects of 5-HT in enhancing L-type Ca(2+) currents, BK(Ca) currents and STOC. 4. In conclusion, 5-HT induces contraction of colonic myocytes, mostly as a result of Ca(2+) release from the sarcoplasmic reticulum (SR) following activation of 5-HT(3) receptors and the inositol 1,4,5-trisphosphate pathway. In addition, the effect of 5-HT in decreasing action potential amplitude is mediated by the release of Ca(2+) from the SR, as well as by enhanced L-type Ca(2+) current. 5-Hydroxytryptamine decreased action potential duration by enhancing BK(Ca) current.
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Affiliation(s)
- Long Xu
- Department of Gastroenterology, Renmin Hospital, Wuhan University, Wuhan, China
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16
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Patten GS, Adams MJ, Dallimore JA, Abeywardena MY. Dietary fish oil dose-response effects on ileal phospholipid fatty acids and contractility. Lipids 2006; 40:925-9. [PMID: 16329465 DOI: 10.1007/s11745-005-1453-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We have reported that dietary fish oil (FO) leads to the incorporation of long-chain n-3 PUFA into the gut tissue of small animal models, affecting contractility, particularly of rat ileum. This study examined the FO dose response for the incorporation of n-3 PUFA into ileal tissue and how this correlated with in vitro contractility. Groups of ten to twelve 13-wk-old Wistar-Kyoto rats were fed 0, 1, 2.5, and 5% FO-supplemented diets balanced with sunflower seed oil for 4 wk, after which ileal total phospholipid FA were determined and in vitro contractility assessed. For the total phospholipid fraction, increasing the dietary FO levels led to a significant increase first evident at 1% FO, with a stepwise, nonsaturating six-fold increase in n-3 PUFA as EPA (20:5n-3), DPA (docosapentaenoic acid, 22:5n-3), and DHA, but mainly as DHA (22:6n-3), replacing the n-6 PUFA linoleic acid (18:2n-6) and arachidonic acid (20:4n-6) over the dosage range. There was no difference in KCl-induced depolarization-driven contractility. However, a significant increase in receptor-dependent maximal contractility occurred at 1% FO for carbachol and at 2.5% FO for prostaglandin E2, with a concomitant increase in sensitivity for prostaglandin E2 at 2.5 and 5% FO. These results demonstrate that significant increases in ileal membrane n-3 PUFA occurred at relatively low doses of dietary FO, with differential receptor-dependent increases in contractility observed for muscarinic and prostanoid agonists.
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17
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Fickl H, Cockeran R, Steel HC, Feldman C, Cowan G, Mitchell TJ, Anderson R. Pneumolysin-mediated activation of NFkappaB in human neutrophils is antagonized by docosahexaenoic acid. Clin Exp Immunol 2005; 140:274-81. [PMID: 15807851 PMCID: PMC1809376 DOI: 10.1111/j.1365-2249.2005.02757.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
This study was designed to investigate the relationship between influx of extracellular Ca(2+), activation of NFkappaB and synthesis of interleukin-8 (IL-8) following exposure of human neutrophils to subcytolytic concentrations (8.37 and 41.75 ng/ml) of the pneumococcal toxin, pneumolysin, as well as the potential of the omega-3 polyunsaturated fatty acid, docosahexaenoic acid, to antagonize these events. Activation and translocation of NFkappaB were measured using a radiometric electrophoretic mobility shift assay, while influx of extracellular Ca(2+) and synthesis of IL-8 were determined using a radioassay and an ELISA procedure, respectively. Exposure of neutrophils to pneumolysin was accompanied by influx of Ca(2+), activation of NFkappaB, and synthesis of IL-8, all of which were eliminated by inclusion of the Ca(2+)-chelating agent, EGTA (10 m m), in the cell-suspending medium, as well as by pretreatment of the cells with docosahexaenoic acid (5 and 10 microg/ml). The antagonistic effects of docosahexaenoic acid on these pro-inflammatory interactions of pneumolysin with neutrophils were not attributable to inactivation of the toxin, and required the continuous presence of the fatty acid. These observations demonstrate that activation of NFkappaB and synthesis of IL-8, following exposure of neutrophils to pneumolysin are dependent on toxin-mediated influx of Ca(2+) and that these potentially harmful activities of the toxin are antagonized by docosahexaenoic acid.
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Affiliation(s)
- H Fickl
- Medical Research Council Unit for Inflammation and Immunity, Department of Immunology, University of PretoriaPretoria
| | - R Cockeran
- Medical Research Council Unit for Inflammation and Immunity, Department of Immunology, University of PretoriaPretoria
| | - H C Steel
- Medical Research Council Unit for Inflammation and Immunity, Department of Immunology, University of PretoriaPretoria
| | - C Feldman
- Division of Pulmonology, Department of Medicine, Johannesburg Hospital and University of the WitwatersrandJohannesburg, South Africa
| | - G Cowan
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of GlasgowGlasgow, UK
| | - T J Mitchell
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of GlasgowGlasgow, UK
| | - R Anderson
- Medical Research Council Unit for Inflammation and Immunity, Department of Immunology, University of PretoriaPretoria
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18
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Hirafuji M, Machida T, Hamaue N, Minami M. Cardiovascular protective effects of n-3 polyunsaturated fatty acids with special emphasis on docosahexaenoic acid. J Pharmacol Sci 2003; 92:308-16. [PMID: 12939515 DOI: 10.1254/jphs.92.308] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
It is widely accepted that n-3 polyunsaturated fatty acids (PUFAs) rich in fish oils protect against several types of cardiovascular diseases such as myocardial infarction, arrhythmia, atherosclerosis, or hypertension. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may be the active biological components of these effects. Although the precise cellular and molecular mechanisms underlying the beneficial effects are still uncertain, the protective effects of n-3 PUFAs are attributable to their direct effects on vascular smooth muscle cell (VSMC) functions. These n-3 PUFAs activate K(+)(ATP) channels and inhibit certain types of Ca(2+) channels, probably via at least 2 distinct mechanisms. N-3 PUFAs favorably alter the eicosanoid profile and regulate cytokine-induced expression of inducible nitric oxide synthase and cyclooxygenase-2 via mechanisms involving modulation of signaling transduction events. N-3 PUFAs also modulate VSMC proliferation, migration, and apoptosis. These recent data suggest that modulation of these VSMC functions contribute to the beneficial effects of n-3 PUFAs on various cardiovascular disorders. Furthermore, recent studies strongly suggest that DHA has more potent and beneficial effects than EPA. However, many questions about the cellular and molecular mechanisms still remain to be answered.
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Affiliation(s)
- Masahiko Hirafuji
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan.
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19
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Engler MM, Engler MB, Pierson DM, Molteni LB, Molteni A. Effects of docosahexaenoic acid on vascular pathology and reactivity in hypertension. Exp Biol Med (Maywood) 2003; 228:299-307. [PMID: 12626775 DOI: 10.1177/153537020322800309] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Previous studies have shown that docosahexaenoic acid (DHA) has an antihypertensive effect in spontaneously hypertensive rats (SHR). To investigate possible mechanisms for this effect, vascular pathology and reactivity were determined in SHR treated with dietary DHA. SHR (7 weeks) were fed a purified diet with either a combination of corn/soybean oils or a DHA-enriched oil for 6 weeks. Histological evaluation of heart tissue, aorta, coronary, and renal arteries was performed. Vascular responses were determined in isolated aortic rings. Contractile responses to agonists, including norepinephrine (10(-9) to 10(-4) M), potassium chloride (5-55 mM), and angiotensin II (5 x 10(-7) M) were assessed. Vasorelaxant responses to acetylcholine (10(-9) to 10 (-4) M), sodium nitroprusside (10(-9) to 10(-6) M), papaverine (10(-5) to 10(-4) M), and methoxyverapamil (D600, 1-100 microM) were determined. DHA-fed SHR had significantly reduced blood pressure (P < 0.001) and vascular wall thicknesses in the coronary, thoracic, and abdominal aorta compared with controls (P < 0.05) Contractile responses to agonists mediated by receptor stimulation and potassium depolarization were not altered in DHA-fed SHR. Endothelial-dependent relaxations to acetylcholine were not altered which suggests endothelial-derived nitric oxide production/release is not affected by dietary DHA. Other mechanisms of vascular relaxation, including intracellular cyclic nucleotides, cGMP, and cAMP were not altered by dietary DHA because aortic relaxant responses to sodium nitroprusside and papaverine were similar in control and DHA-fed SHR. No significant differences were seen in relaxant responses to the calcium channel blocker, D600, or contractile responses to norepinephrine in the absence of extracellular calcium. These results suggest that dietary DHA does not affect mechanisms related to extracellular calcium channels or intracellular calcium mobilization. Moreover, the contractile and vasorelaxant responses are not differentially altered with dietary DHA in this in vivo SHR model. The findings demonstrate that dietary DHA reduces systolic blood pressure and vascular wall thickness in SHR. This may contribute to decrease arterial stiffness and pulse pressure, in addition to the antihypertensive properties of DHA. The antihypertensive properties of DHA are not related to alterations in vascular responses.
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Affiliation(s)
- Marguerite M Engler
- Laboratory of Cardiovascular Physiology, Department of Physiological Nursing, University of California, San Francisco, California 94143-0610, USA.
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20
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Hirafuji M, Machida T, Tsunoda M, Miyamoto A, Minami M. Docosahexaenoic acid potentiates interleukin-1beta induction of nitric oxide synthase through mechanism involving p44/42 MAPK activation in rat vascular smooth muscle cells. Br J Pharmacol 2002; 136:613-9. [PMID: 12055140 PMCID: PMC1573387 DOI: 10.1038/sj.bjp.0704768] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The effect of docosahexaenoic acid (DHA) on nitric oxide (NO) production and inducible NO synthase (iNOS) expression induced by interleukin (IL)-1beta, and whether the effect of DHA is related to its effect on mitogen-activated protein kinase (MAPK) activation were investigated in cultured rat vascular smooth muscle cells (VSMCs). DHA and eicosapentaenoic acid (EPA), although less potent, increased the NO production induced by IL-1beta (3 ng ml(-1)) in a concentration-dependent manner (3 - 30 microM) Arachidonic acid had no significant effect. The stimulatory effect of DHA (30 microM) on the NO production was more obvious at lower concentrations of IL-1beta. IL-1beta induced iNOS protein and mRNA expressions, which were significantly potentiated by DHA. EPA (30 microM) had a tendency to increase the iNOS protein and mRNA expressions, but arachidonic acid had no effect. IL-1beta-induced iNOS protein expression was significantly inhibited by PD 98059 (10 microM), a selective inhibitor of p44/42 MAPK kinase, both in the absence and the presence of DHA. SB 203580 (10 microM), a selective inhibitor of p38 MAPK activity, had no significant effect, although had a tendency to inhibit slightly. IL-1beta increased the phosphorylation of p44/42 MAPK, while it did not apparently increase the phosphorylation of p38 MAPK. DHA significantly potentiated the IL-1beta-induced phosphorylation of p44/42 MAPK, while it had no significant effect on the phosphorylation of p38 MAPK. These results suggest that DHA increases NO production by potentiating iNOS expression induced by IL-1beta through mechanism involving p44/42 MAPK signalling cascade in rat VSMCs. The present study may contribute to the understanding of basic mechanisms underlying the beneficial effects of DHA on various cardiovascular disorders.
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MESH Headings
- Animals
- Arachidonic Acid/pharmacology
- Blotting, Western
- Cells, Cultured
- Docosahexaenoic Acids/pharmacology
- Eicosapentaenoic Acid/pharmacology
- Enzyme Activation
- Interleukin-1/metabolism
- Interleukin-1/pharmacology
- Mitogen-Activated Protein Kinase 1/antagonists & inhibitors
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases/antagonists & inhibitors
- Mitogen-Activated Protein Kinases/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Nitric Oxide/biosynthesis
- Nitric Oxide Synthase/biosynthesis
- Nitric Oxide Synthase/genetics
- Nitric Oxide Synthase Type II
- RNA, Messenger/biosynthesis
- Rats
- Rats, Inbred WKY
- Reverse Transcriptase Polymerase Chain Reaction
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Affiliation(s)
- Masahiko Hirafuji
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
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