当前位置:首页 >> 医药卫生 >>


Dietary n-3 Polyunsaturated Fatty Acids and Direct Renin Inhibition Improve Electrical Remodeling in a Model of High Human Renin Hypertension Robert Fischer, Ralf Dechend, Fatimunnisa Qadri, Marija Markovic, Sandra Feldt, Florian Herse, Joon-Keun Park, Andrej Gapelyuk, Ines Schwarz, Udo B. Zacharzowsky, Ralph Plehm, Erdal Safak, Arnd Heuser, Alexander Schirdewan, Friedrich C. Luft, Wolf-Hagen Schunck and Dominik N. Muller Hypertension 2008;51;540-546; originally published online Dec 24, 2007; DOI: 10.1161/HYPERTENSIONAHA.107.103143
Hypertension is published by the American Heart Association. 7272 Greenville Avenue, Dallas, TX 72514 Copyright ? 2008 American Heart Association. All rights reserved. Print ISSN: 0194-911X. Online ISSN: 1524-4563

The online version of this article, along with updated information and services, is located on the World Wide Web at: http://hyper.ahajournals.org/cgi/content/full/51/2/540

Subscriptions: Information about subscribing to Hypertension is online at http://hyper.ahajournals.org/subscriptions/ Permissions: Permissions & Rights Desk, Lippincott Williams & Wilkins, a division of Wolters Kluwer Health, 351 West Camden Street, Baltimore, MD 21202-2436. Phone: 410-528-4050. Fax: 410-528-8550. E-mail: journalpermissions@lww.com Reprints: Information about reprints can be found online at http://www.lww.com/reprints

Downloaded from hyper.ahajournals.org by on March 16, 2011

Dietary n-3 Polyunsaturated Fatty Acids and Direct Renin Inhibition Improve Electrical Remodeling in a Model of High Human Renin Hypertension
Robert Fischer, Ralf Dechend, Fatimunnisa Qadri, Marija Markovic, Sandra Feldt, Florian Herse, Joon-Keun Park, Andrej Gapelyuk, Ines Schwarz, Udo B. Zacharzowsky, Ralph Plehm, Erdal Safak, Arnd Heuser, Alexander Schirdewan, Friedrich C. Luft, Wolf-Hagen Schunck, Dominik N. Muller
Abstract—We compared the effect n-3 polyunsaturated fatty acids (PUFAs) with direct renin inhibition on electrophysiological remodeling in angiotensin II–induced cardiac injury. We treated double-transgenic rats expressing the human renin and angiotensinogen genes (dTGRs) from week 4 to 7 with n-3 PUFA ethyl-esters (Omacor; 25-g/kg diet) or a direct renin inhibitor (aliskiren; 3 mg/kg per day). Sprague-Dawley rats were controls. We performed electrocardiographic, magnetocardiographic, and programmed electrical stimulation. Dietary n-3 PUFAs increased the cardiac content of eicosapentaenoic and docosahexaenoic acid. At week 7, mortality in dTGRs was 31%, whereas none of the n-3 PUFA- or aliskiren-treated dTGRs died. Systolic blood pressure was modestly reduced in n-3 PUFA-treated (180 3 mm Hg) compared with dTGRs (208 5 mm Hg). Aliskiren-treated dTGRs and SpragueDawley rats were normotensive (110 3 and 119 6 mm Hg, respectively). Both n-3 PUFA–treated and untreated dTGRs showed cardiac hypertrophy and increased atrial natriuretic peptide levels. Prolonged QRS and QTc intervals and increased T-wave dispersion in dTGRs were reduced by n-3 PUFAs or aliskiren. Both treatments reduced arrhythmia induction from 75% in dTGRs to 17% versus 0% in Sprague-Dawley rats. Macrophage infiltration and fibrosis were reduced by n-3 PUFAs and aliskiren. Connexin 43, a mediator of intermyocyte conduction, was redistributed to the lateral cell membranes in dTGRs. n-3 PUFAs and aliskiren restored normal localization to the intercalated disks. Thus, n-3 PUFAs and aliskiren improved electrical remodeling, arrhythmia induction, and connexin 43 expression, despite a 70-mm Hg difference in blood pressure and the development of cardiac hypertrophy. (Hypertension. 2008;51[part 2]:540-546.) Key Words: angiotensin II renin inhibition n-3 PUFA arrhythmias magnetocardiography

ypertensive heart disease causes heart failure and arrhythmia propensity. Ischemia, cardiac hypertrophy, fibrosis, inflammation, and electrical remodeling all contribute to the pathogenesis.1,2 The renin-angiotensin-aldosterone system is a primary driver, and its blockade is state-of-the-art therapy. We provided initial evidence that direct renin inhibition (DRI) in transgenic rats harboring the human renin and angiotensinogen genes (dTGRs) improves target organ damage.3–5 Untreated dTGRs developed severe hypertension, hypertrophy, inflammation, fibrosis, and small myocardial infarctions. Ventricular arrhythmias and, consequently, sudden cardiac death contributed to the high mortality rate at the early age of 7 weeks.6 Electrical remodeling in dTGRs included dysregulation of the Ito potassium channel, Ca2 cycling proteins, and connexin (Cx) 43 gap junctions.6,7 n-3 polyunsaturated fatty acids (PUFAs), contained in marine fish


oil, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), lead to cardioprotection and reduce sudden cardiac death.8 The molecular mechanisms by which n-3 PUFAs exert their cardioprotective effects are not fully understood. n-3 PUFAs putatively affect membrane ion channels.9,10 They exert antihypertensive, antiproliferative, anti-inflammatory, and anticoagulative properties.11 In spontaneously hypertensive rats, n-3 PUFA treatment lowered blood pressure.12 The reduced vasoconstriction was mediated by inhibition of angiotensin II (Ang II)–induced intracellular Ca2 mobilization and protein kinase C phosphorylation.13 In our dTGR model, chronic n-3 PUFA treatment lowered blood pressure and improved renal and cardiac damage.14 We now investigated the impact of n-3 PUFAs and DRI on cardiac electrophysiological remodeling in the dTGR, a model of high human renin hypertension.

Received October 12, 2007; first decision October 30, 2007; revision accepted November 28, 2007. From the Medical Faculty of the Charite (R.F., R.D., S.F., F.H., A.G., I.S., U.B.Z., E.S., A.S., F.C.L., D.N.M.), Experimental and Clinical Research ? Center, Franz Volhard Clinic and HELIOS Klinikum Berlin-Buch, Berlin, Germany; Max-Delbrueck-Center for Molecular Medicine (F.Q., M.M., R.P., A.H., F.C.L., W-H.S., D.N.M.), Berlin-Buch, Germany; Medical School of Hannover (J-K.P.), Hannover, Germany. The first 2 authors contributed equally to this work. Correspondence to Robert Fischer, Experimental and Clinical Research Center, Max-Delbrueck-Center, Lindenberger Weg 80, 13125 Berlin, Germany. E-mail robert.fischer@charite.de ? 2008 American Heart Association, Inc. Hypertension is available at http://hyper.ahajournals.org DOI: 10.1161/HYPERTENSIONAHA.107.103143

540 Downloaded from hyper.ahajournals.org by on March 16, 2011

Fischer et al

Cardioprotection by n-3 PUFA


Figure 1. A, The standard chow was free of EPA and DHA and contained high amounts of linoleic acid (C18:2 n-6). Note the presence of -linolenic acid (C18:3 n-3), which may explain the relatively high cardiac DHA content already in animals fed with the standard chow The Omacor-supplemented chow differed from the standard chow solely by the additional presence of EPA and DHA. B, dTGRs fed with the Omacor-supplemented diet showed a marked increase of the cardiac omega-3 index calculated as (EPA DHA)/ total fatty acids in percentages. C, The cardiac content of EPA (20:5 n-3) and DHA (22:6 n-3) was increased, and the content of AA (20:4 n-6) was reduced in dTGRs fed with the Omacor-supplemented diet compared with untreated dTGRs. Cardiac fatty acid composition was analyzed in 7-week– old animals (n 6 per group). The total fatty acid contents (micrograms per milligram of cardiac tissue) were 18.6 1 (dTGR), 18.6 0.7 (Omacortreated dTGR), 25.4 1 (Aliskiren-treated dTGR), and 18.8 0.6 (SD).

Experimental Design
We studied male dTGRs (RCC Ltd) and age-matched nontransgenic Sprague-Dawley (SD) rats (Tierzucht Schonwalde).4,7,15,16 Local ¨ authorities approved the studies, and we followed American Physiological Society guidelines. Omacor, a mixture of highly concentrated n-3 PUFAs containing 46% EPA- and 38% DHA-ethyl-esters, was provided by Solvay Pharmaceuticals. Novartis Pharmaceuticals provided the DRI, aliskiren. We compared untreated dTGRs (n 16), dTGR Omacor (25-g/kg diet; n 18), dTGR aliskiren (3 mg/kg per day by osmotic mini pump; n 9), and SD (n 10) rats. We used a higher number of untreated and Omacor-treated dTGRs, because we could not predict their mortality. Treatment was started at the age of 4 weeks. ECG, magnetocardiography (MCG), and systolic blood pressure (by tail cuff) were determined at week 7. Rats were euthanized by decapitation at the age of 7 weeks. Serum and plasma were collected for further analysis. Hearts were removed and washed with ice-cold saline, blotted dry, and weighed. In a second protocol, 7-week– old rats (dTGR: n 8; dTGR Omacor: n 9; dTGR aliskiren: n 8; SD: n 7) were subjected to in vivo programmed electrical stimulations.

Immunohistochemistry and Quantitative TaqMan RT-PCR
Ice-cold acetone-fixed cryosections (6 m) were stained by immunofluorescence techniques, as described earlier.19 The following monoclonal antibodies were used: anti–ED-1, antifibronectin, and anticollagen I (Southern Biotechnology), as well as polyclonal rabbit anti–Cx-43 (Sigma; please see the data supplement). RNA isolation and TaqMan RT-PCR were performed as described earlier.7 We analyzed LV tissue for atrial natriuretic peptide mRNA expression. Each sample was in triplicate. The target sequences were normalized in relation to the 36B4 product. The primer sequence is available on request (Biotez).

Data are presented as mean SEM. Differences in mean values were tested by nonparametric Mann-Whitney exact test; arrhythmia induction was tested by 2. A value of P 0.05 was considered significant. The data were analyzed using SPSS.

Untreated dTGRs, dTGR aliskiren, and SD rats were fed standard chow, whereas Omacor-treated dTGRs received the n-3 PUFA-rich diet. This diet contained EPA and DHA in amounts representing 5.6% and 4.1% of total fatty acids, respectively (Figure 1A). Chronic n-3 PUFA treatment resulted in a marked increase of the cardiac omega-3 index (29.6 0.3% for dTGR Omacor versus 9.8 0.6% for dTGRs, 5.9 0.2% for dTGR aliskiren, and 6.2 0.3% for SD rats; P 0.05; Figure 1B). Cardiac EPA and DHA levels were significantly increased in Omacor-treated dTGRs compared with untreated dTGRs (1.9 0.05% versus 0.07 0.005% for EPA and 27.6 0.3% versus 9.7 0.6% for DHA, respectively; Figure 1C). The cardiac arachidonic acid (AA) levels decreased from 32.2 0.5 for dTGRs to 16.3 0.2 for dTGR Omacor rats (P 0.05), indicating that AA was partially replaced by EPA and DHA. The content of all other fatty acids remained largely unaffected (Figure 1C). The cardiac fatty acid composition of SD control rats and of dTGRs treated with aliskiren was not different.

ECG, MCG, and In Vivo Electrophysiological Studies
ECG and MCG were done under slight isoflurane anesthesia as described previously.6,17,18 Programmed electrical stimulation was performed as reported recently6 (please see the data supplement available at http://hyper.ahajournals.org).

Fatty Acid Composition
Left-ventricular heart tissue (n 6 per animal group) was frozen in liquid nitrogen and homogenized using a biopulverizer (Biospec Products Inc). Aliquots (10 mg) were treated with tetramethylammonium hydroxide pentahydrate, and the released free fatty acids were analyzed by liquid chromatography/mass spectrometry (FILT GmbH). Separation was performed on a Gemini column (5 m of C18, 150 3 mm) using an ammonium acetate/acetonitrile gradient at pH 9.5. A negative single ion monitoring mode was used for the detection of the individual fatty acids. Pentadecanoic acid served as an internal standard, and quantification of individual fatty acids was performed using respective calibration curves. The same procedure was applied to determine the fatty acid composition of the different chows used for rat feeding.

Downloaded from hyper.ahajournals.org by on March 16, 2011



February 2008 Part II

Figure 2. A, Untreated dTGRs showed high mortality (5 of 16), which was reduced to 0 by Omacor (0 of 18) and aliskiren (0 of 9) treatment. None of the SD controls died (n 10). B, At the age of 7 weeks, Omacor reduced blood pressure only slightly, whereas aliskiren normalized it. C, Untreated and Omacortreated dTGRs both showed increased cardiac weight compared with aliskiren-treated dTGRs and SD rats. D, Left-ventricular ANP mRNA expression, as a marker for cardiac hypertrophy, con?rmed the results. Results are mean SEM. *P 0.05 vs untreated dTGRs; # P 0.05 vs dTGR Omacor rats.

Untreated dTGRs showed 31% mortality at age 7 weeks (5 of 16; Figure 2A). In contrast, none of the Omacor and aliskiren-treated dTGRs died. Untreated dTGRs developed high systolic blood pressure, which was modestly reduced by Omacor treatment (208 5 versus 180 3 mm Hg; P 0.05; Figure 2B). In contrast, aliskiren-treated dTGRs and SD controls were normotensive (110 3 and 119 6 mm Hg, respectively). Omacor-treated and untreated dTGRs showed both increased heart weights compared with SD (1203 21 and 1213 24 mg versus 933 17 mg; P 0.05; Figure 2C). Only aliskiren prevented cardiac hypertrophy (972 13 mg). ANP expression confirmed the differences in cardiac hypertrophy between the groups. Although Omacor treated and untreated dTGRs showed high levels of ANP mRNA (24 2 and 20 1 arbitrary units), ANP expression was normalized in aliskirentreated dTGRs (2.4 0.2 and 1.8 0.2 for SD; Figure 2D). To analyze whether the reduced mortality might be because of lessened sudden cardiac death, we tested for arrhythmia induction. Programmed electrical stimulation showed a high nonsustained and sustained ventricular tachycardia induction rate in untreated dTGRs (75%; Figure 3A). In SD controls, the same protocol never initiated arrhythmias. The arrhythmia induction was reduced to the same extent by both treatments. Only 17% of the Omacor-treated and 17% of aliskiren-treated dTGRs responded to electrical stimulation with ventricular tachycardia (P 0.05 versus untreated dTGRs). The ventricular effective refractory period was prolonged in dTGRs compared with SD controls (54.5 1.9 versus 45.4 2 ms; P 0.05) but significantly reduced by both treatments (Omacor and aliskiren: 49 1.5 and 49.3 1.6 ms, P 0.05, respectively; Figure 3B and 3C).

Disturbance in the ventricular refractory period indicated changes in the electrophysiological phenotype, which was confirmed by ECG and MCG. The prolonged QRS interval in dTGRs compared with SD controls (21 0.5 versus 18.4 0.2 ms; P 0.05; Figure 4A) was similarly reduced by both treatments (Omacor and aliskiren: 19.1 0.1 and 19 0.3 ms, P 0.05, respectively). In contrast, the acquired long QT syndrome in dTGRs (QTPeak and QTc: 42 1 and 109 3 ms versus SD: 30 1 and 75 3 ms, P 0.05, respectively) was only prevented by aliskiren treatment (31 1 and 79 3 ms; Figure 4B and 4C). However, Omacor reduced the repolarization period (QTPeak and QTc: 37 1 and 99 2 ms, P 0.05, respectively). T-wave dispersion assessed by MCG surface mapping was slightly reduced in Omacor-treated compared with untreated dTGRs (12.9 0.5 versus 14.5 0.6 ms; P 0.05; Figure 4D). Aliskiren completely normalized QTPeak dispersion (6 0.7 versus SD 5.9 0.8 ms). Untreated dTGRs showed marked fibrosis. Cardiac immunoreactivity for collagen I was observed predominantly perivascularly, whereas fibronectin expression was predominantly interstitial. Aliskiren treatment and n-3 PUFA supplementation substantially reduced both matrix depositions (Figure 5A and 5B). ED-1, a marker of monocyte/macrophage infiltration, showed prevalent inflammation in untreated dTGRs. Both treatments reduced monocyte/macrophage infiltration to the SD level (Figure 5C). Cx43 gap junction dislocation is a mechanism of dTGR electrical remodeling. We found pronounced Cx43 immunoreactivity at the lateral cardiomyocyte borders (Figure 5D). In contrast, Cx43 was restricted to the intercalated disc regions in SD. Surprisingly, hypertrophied hearts of Omacor-treated dTGRs showed normal Cx43 gap junction localization. Aliskiren also prevented abnormal Cx43 expression.

Downloaded from hyper.ahajournals.org by on March 16, 2011

Fischer et al

Cardioprotection by n-3 PUFA


Figure 3. In vivo electrophysiological studies in 7-week– old dTGRs (n 8), dTGR Omacor (n 9), dTGR aliskiren (n 8), and SD (n 7) rats. A, The ?gure shows inducibility of ventricular arrhythmias by in vivo–programmed electrical stimulation. Given is the number of stimulation protocols with inducible arrhythmias from all of the performed stimulation protocols in percentages. B, The left-ventricular effective refractory period was prolonged in untreated dTGRs. Both treatments reduced ventricular refractory. *P 0.05 vs dTGRs ; # P 0.05 vs dTGR Omacor rats, . . ., P 0.05 vs dTGR aliskiren) C, Given are representative results of programmed electrical stimulation from all of the groups. One ECG is shown simultaneously with indicators of delivered electrical stimuli (Stim). Untreated dTGRs showed reproducible inducibility of ventricular tachyarrhythmias, whereas in most cases the same stimulations showed no inducibility in both treatment groups. In SD controls, no arrhythmias were inducible.

We showed that an n-3 PUFA– based intervention reduced mortality in our model to 0. n-3 PUFA supplementation reduced electrophysiological alterations to a similar extent as the DRI aliskiren, despite a 70-mm Hg difference in blood pressure and the development of cardiac hypertrophy. These results indicate that the levels of blood pressure and cardiac hypertrophy are not the sole determinants for increased arrhythmias. Both treatments prevented inflammation, fibro-

sis, and dyslocalization of Cx43 gap junctions. Therefore, reduction in arrhythmias or sudden death may depend on a nonmorphological tissue architecture and organized cell-cell coupling compared with cardiac hypertrophy, per se. DRI now offers a novel opportunity in treating hypertensive heart disease. Aliskiren was recently approved for the treatment of hypertension.20,21 Aliskiren strongly reduced ventricular tachycardia induction, QRS, and QT prolongation, and increased T-wave dispersion. To our knowledge, this

Figure 4. A, QRS interval was signi?cantly prolonged in untreated dTGRs. Both treatments reduced QRS intervals to the same extent. B and C, Repolarization was pronlonged in untreated dTGRs indicated by an acquired long QT syndrome. Aliskiren normalized QT intervals, whereas Omacor reduced QT intervals. D, The temporal dispersion of the peak of T wave was assessed by magnetocardiographic surface mapping. The ?gure gives the maximal difference in TPEAK within a square area of 60 60 mm over the animal’s thorax. The high TPeak dispersion of untreated dTGRs was signi?cantly reduced by Omacor treatment. Aliskiren reduced it to control levels. *P 0.05 vs dTGRs, # P 0.05 vs dTGR Omacor rats. These data were obtained using the same animals as in Figure 3.

Downloaded from hyper.ahajournals.org by on March 16, 2011



February 2008 Part II

Figure 5. A and B, Omacor and aliskiren treatment reduced collagen I and ?bronectin deposition. C, Cardiac monocyte and macrophage in?ltration (ED-1 cells) was normalized by Omacor and aliskiren treatment compared with untreated dTGRs. Results are mean SEM. *P 0.05 vs untreated dTGRs; n 5 per group. D, Cx43 immunostainings demonstrated a diffuse localization in untreated dTGRs (lateral cell borders: closed arrowheads) and a restoration of proper Cx43 localization to the intercalated disks (open arrowheads) on treatments with aliskiren and Omacor. A, B, and D show representative immunohistochemical results, obtained from 30 inspected cardiac areas (n 5 animals per group).

report is the first study demonstrating the impact of DRI in Ang II–induced electrical remodeling. Renin-angiotensin system inhibition is 1 of the important strategies to prevent electrical remodeling– based arrhythmias. Ang II promotes the release of aldosterone. Both hormones are strong inducers of fibrosis and inflammation that contribute to the pathogenesis of heart failure and electrical remodeling. Furthermore, Ang II and aldosterone affect Ca2 cycling, decrease conduction velocity as a result of cell-to-cell-uncoupling, and lead to increased dispersion of repolarization by inhibiting potassium channels.22 In humans, angiotensin-converting enzyme inhibitors, angiotensin type 1 receptor blockers, and mineralocorticoid receptor blockers all exhibited antiarrhythmic potential.23 Currently, no human study has addressed the effect of DRI on electrical remodeling. We did not measure plasma renin activity and aldosterone levels in this study, but showed earlier that aliskiren reduces plasma renin activity.16 We do not believe that Omacor reduced plasma renin activity, because its blood pressure effect was modest. In humans, n-3 PUFAs decreased the risk of sudden cardiac death from ventricular arrhythmias in coronary artery– diseased patients.11,24 –26 The Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto-Prevenzione Study showed a 45% reduction in sudden cardiac death in patients with recent myocardial infarction.25 In patients after coronary artery bypass graft surgery, n-3 PUFAs reduced atrial fibrillation by almost 55%.26 This antiarrhythmic effect also applies to our model of Ang II–induced sudden cardiac death. n-3 PUFA was as effective in reducing mortality and arrhythmia induction as was DRI. This finding is surprising, because n-3 PUFA–treated dTGRs had 70-mm Hg higher blood pressure, as well as unchanged cardiac hypertrophy, with elevated ANP expression. The slight reduction in blood pressure by n-3 PUFA in dTGRs is in agreement with the antihyperten-

sive effect described in other studies. We believe that blood pressure and cardiac hypertrophy are not the sole determinants for our electrophysiological phenotype. First, both treatment strategies reduced the likelihood of arrhythmias despite a 70-mm Hg blood pressure difference. We showed in a previous study in the same model that triple therapy with hydralazine, reserpine, and hydrochlorothiazide normalized blood pressure but just delayed and did not prevent inflammatory cardiac damage.16 Second, studies in mice with restricted cardiac high Ang II levels and heart-specific mineralocorticoid receptor overexpression showed sudden cardiac death, arrhythmias, and electrical remodeling despite normal blood pressure.27–29 Taken together these results support the hypothesis that Ang II increases the risk for arrhythmias by blood pressure– dependent and independent mechanisms, which can be inhibited by aliskiren and n-3 PUFA treatment. The marked reductions in the QRS interval and in arrhythmia induction suggest an improvement in conduction. The factors most likely responsible are fibrosis and Cx43 gap junctions, which are crucial for electrical coupling of adjacent cardiomyocytes. Indeed, we found reduced fibrosis and, more surprisingly, a normal subcellular distribution of Cx43 in both treatment groups. Ang II–induced gap junction dyslocalization in untreated dTGRs was probably due to changes in the Cx43 phosphorylation state.30 Cx43 redistribution also occurs under conditions of ischemia and contributes to electrical uncoupling of cardiomyocytes and the development of arrhythmias. Cardiac preconditioning was shown to prevent intracellular Cx43 redistribution and to protect against cardiac injury and arrhythmias during subsequent attacks of prolonged ischemia.31 We are the first to show that there is also a direct link between the antiarrhythmic properties of n-3 PUFAs and restoration of proper Cx43 localization to the

Downloaded from hyper.ahajournals.org by on March 16, 2011

Fischer et al
intercalated disks. DHA also improved the functional localization of Cx43 in astrocytes,32 indicating the existence of common mechanisms of how n-3 PUFAs may improve gap junction coupling in heart and brain cells. The modulation of cellular electrophysiology by n-3 PUFAs further includes the reduction of membrane excitability by modulating the function of specific ion channels and the Ca2 release from the sarcoplasmic reticulum.9,33–35 In humans, n-3 PUFA supplementation reduced the QT interval.36 A similar amelioration of repolarization parameters was demonstrated in our study. However, the distinct molecular pathways by which n-3 PUFAs exert their antiarrhythmic effects and reduce the risk of sudden cardiac death are unknown. n-3 PUFAs may directly interact with certain cellular targets or change the microenvironment of membrane-bound signaling components after being incorporated into phospholipids. Moreover, n-3 PUFAs are substrates for cytochrome P450, cyclooxygenase, and lipoxygenase enzymes.37 Thus, depending on the diet, n-3 PUFAs are a potential source of biologically active metabolites produced in competition with AA-derived eicosanoids. Among these metabolites, cytochrome P450 – dependent epoxy derivates may be of particular interest because they act as potent activators of cardiac ATP-sensitive potassium (KATP) channels. KATP channels play a central role in cardiac protection and are essential for the beneficial effect of preconditioning on subcellular Cx43 distribution.31 The principal capacity of KATP channel activation occurs already with some AA-derived metabolites (epoxyeicosatrienoic acids) but is largely exceeded by their EPA- and DHA-derived counterparts.38 Enhanced epoxyeicosatrienoic acid generation was shown to exert cardioprotective effects via KATP channel activation.39 – 41 Taken together, we speculate that the effects of n-3 PUFAs are in part mediated by cytochrome P450 – dependent formation of alternative highly potent KATP channel activators.

Cardioprotection by n-3 PUFA


DRI and n-3 PUFAs may be future potent therapeutic agents providing cardioprotection and reduction in the risk of arrhythmias in particular. The combination of both therapies might be useful in patients with hypertension-induced heart disease. The discovery of the n-3 PUFA signaling pathway may present new candidates for antiarrhythmic drugs.

We thank Astrid Schiche, Jutta Meisel, and Gabriele N diaye for technical assistance.

Sources of Funding
Grants-in-Aid from the European Union (EuReGene), Solvay Pharmaceuticals, the Novartis Foundation, and the Deutsche Forschungsgemeinschaft to W-H.S., D.N.M. and F.C.L. supported the studies.

F.C.L. and D.N.M. have served as advisors for Novartis and have lectured on aliskiren. F.C.L. is a member of the Renin Academy. The remaining authors report no conflicts.

1. Hill JA. Electrical remodeling in cardiac hypertrophy. Trends Cardiovasc Med. 2003;13:316 –322.

2. Brown DW, Giles WH, Croft JB. Left ventricular hypertrophy as a predictor of coronary heart disease mortality and the effect of hypertension. Am Heart J. 2000;140:848 – 856. 3. Pilz B, Shagdarsuren E, Wellner M, Fiebeler A, Dechend R, Gratze P, Meiners S, Feldman DL, Webb RL, Garrelds IM, Jan Danser AH, Luft FC, Muller DN. Aliskiren, a human renin inhibitor, ameliorates cardiac and renal damage in double-transgenic rats. Hypertension. 2005;46: 569 –576. 4. Shagdarsuren E, Wellner M, Braesen JH, Park JK, Fiebeler A, Henke N, Dechend R, Gratze P, Luft FC, Muller DN. Complement activation in angiotensin II-induced organ damage. Circ Res. 2005;97:716 –724. 5. Dechend R, Shagdarsuren E, Gratze P, Fiebeler A, Pilz B, Meiners S, Derer W, Feldman DL, Webb R, Muller DN. Low-dose renin inhibitor and low-dose AT(1)-receptor blocker therapy ameliorate target-organ damage in rats harbouring human renin and angiotensinogen genes. J Renin Angiotensin Aldosterone Syst. 2007;8:81– 84. 6. Fischer R, Dechend R, Gapelyuk A, Shagdarsuren E, Gruner K, Gruner A, Gratze P, Qadri F, Wellner M, Fiebeler A, Dietz R, Luft FC, Muller DN, Schirdewan A. Angiotensin II-induced sudden arrhythmic death and electrical remodeling. Am J Physiol Heart Circ Physiol. 2007;293: H1242–H1253. 7. Wellner M, Dechend R, Park JK, Shagdarsuren E, Al-Saadi N, Kirsch T, Gratze P, Schneider W, Meiners S, Fiebeler A, Haller H, Luft FC, Muller DN. Cardiac gene expression profile in rats with terminal heart failure and cachexia. Physiol Genomics. 2005;20:256 –267. 8. Breslow JL. n-3 fatty acids and cardiovascular disease. Am J Clin Nutr. 2006;83:1477S–1482S. 9. Danthi SJ, Enyeart JA, Enyeart JJ. Modulation of native T-type calcium channels by omega-3 fatty acids. Biochem Biophys Res Commun. 2005; 327:485– 493. 10. Xiao YF, Sigg DC, Leaf A. The antiarrhythmic effect of n-3 polyunsaturated fatty acids: modulation of cardiac ion channels as a potential mechanism. J Membr Biol. 2005;206:141–154. 11. Thies F, Garry JM, Yaqoob P, Rerkasem K, Williams J, Shearman CP, Gallagher PJ, Calder PC, Grimble RF. Association of n-3 polyunsaturated fatty acids with stability of atherosclerotic plaques: a randomised controlled trial. Lancet. 2003;361:477– 485. 12. Yin K, Chu ZM, Beilin LJ. Effect of fish oil feeding on blood pressure and vascular reactivity in spontaneously hypertensive rats. Clin Exp Pharmacol Physiol. 1990;17:235–239. 13. Nyby MD, Hori MT, Ormsby B, Gabrielian A, Tuck ML. Eicosapentaenoic acid inhibits Ca2 mobilization and PKC activity in vascular smooth muscle cells. Am J Hypertens. 2003;16:708 –714. 14. Theuer J, Shagdarsuren E, Muller DN, Kaergel E, Honeck H, Park JK, Fiebeler A, Dechend R, Haller H, Luft FC, Schunck WH. Inducible NOS inhibition, eicosapentaenoic acid supplementation, and angiotensin II-induced renal damage. Kidney Int. 2005;67:248 –258. 15. Ganten D, Wagner J, Zeh K, Bader M, Michel JB, Paul M, Zimmermann F, Ruf P, Hilgenfeldt U, Ganten U, Kaling M, Bachmann S, Fukamizu A, Mullins J, Murakami K. Species specificity of renin kinetics in transgenic rats harboring the human renin and angiotensinogen genes. Proc Natl Acad Sci U S A. 1992;89:7806 –7810. 16. Mervaala E, Muller DN, Schmidt F, Park JK, Gross V, Bader M, Breu V, Ganten D, Haller H, Luft FC. Blood pressure-independent effects in rats with human renin and angiotensinogen genes. Hypertension. 2000;35: 587–594. 17. Royer A, van Veen TA, Le Bouter S, Marionneau C, Griol-Charhbili V, Leoni AL, Steenman M, van Rijen HV, Demolombe S, Goddard CA, Richer C, Escoubet B, Jarry-Guichard T, Colledge WH, Gros D, de Bakker JM, Grace AA, Escande D, Charpentier F. Mouse model of SCN5A-linked hereditary Lenegre’s disease: age-related conduction slowing and myocardial fibrosis. Circulation. 2005;111:1738 –1746. 18. Volk T, Nguyen TH, Schultz JH, Faulhaber J, Ehmke H. Regional alterations of repolarizing K currents among the left ventricular free wall of rats with ascending aortic stenosis. J Physiol. 2001;530:443– 455. 19. Muller DN, Shagdarsuren E, Park JK, Dechend R, Mervaala E, Hampich F, Fiebeler A, Ju X, Finckenberg P, Theuer J, Viedt C, Kreuzer J, Heidecke H, Haller H, Zenke M, Luft FC. Immunosuppressive treatment protects against angiotensin II-induced renal damage. Am J Pathol. 2002; 161:1679 –1693. 20. O’Brien E, Barton J, Nussberger J, Mulcahy D, Jensen C, Dicker P, Stanton A. Aliskiren reduces blood pressure and suppresses plasma renin activity in combination with a thiazide diuretic, an angiotensin-converting enzyme inhibitor, or an angiotensin receptor blocker. Hypertension. 2007; 49:276 –284.

Downloaded from hyper.ahajournals.org by on March 16, 2011



February 2008 Part II
sin-converting enzyme overexpression causes conduction defects and connexin dysregulation. Am J Physiol Heart Circ Physiol. 2007;293: H182–H192. Jain SK, Schuessler RB, Saffitz JE. Mechanisms of delayed electrical uncoupling induced by ischemic preconditioning. Circ Res. 2003;92: 1138 –1144. Champeil-Potokar G, Chaumontet C, Guesnet P, Lavialle M, Denis I. Docosahexaenoic acid (22:6n-3) enrichment of membrane phospholipids increases gap junction coupling capacity in cultured astrocytes. Eur J Neurosci. 2006;24:3084 –3090. Xiao YF, Gomez AM, Morgan JP, Lederer WJ, Leaf A. Suppression of voltage-gated L-type Ca2 currents by polyunsaturated fatty acids in adult and neonatal rat ventricular myocytes. Proc Natl Acad Sci U S A. 1997;94:4182– 4187. Swan JS, Dibb K, Negretti N, O’Neill SC, Sitsapesan R. Effects of eicosapentaenoic acid on cardiac SR Ca(2 )-release and ryanodine receptor function. Cardiovasc Res. 2003;60:337–346. Pepe S, Bogdanov K, Hallaq H, Spurgeon H, Leaf A, Lakatta E. Omega 3 polyunsaturated fatty acid modulates dihydropyridine effects on L-type Ca2 channels, cytosolic Ca2 , and contraction in adult rat cardiac myocytes. Proc Natl Acad Sci U S A. 1994;91:8832– 8836. Mozaffarian D, Prineas RJ, Stein PK, Siscovick DS. Dietary fish and n-3 fatty acid intake and cardiac electrocardiographic parameters in humans. J Am Coll Cardiol. 2006;48:478 – 484. Jump DB. The biochemistry of n-3 polyunsaturated fatty acids. J Biol Chem. 2002;277:8755– 8758. Lu T, VanRollins M, Lee HC. Stereospecific activation of cardiac ATPsensitive K( ) channels by epoxyeicosatrienoic acids: a structural determinant study. Mol Pharmacol. 2002;62:1076 –1083. Seubert J, Yang B, Bradbury JA, Graves J, Degraff LM, Gabel S, Gooch R, Foley J, Newman J, Mao L, Rockman HA, Hammock BD, Murphy E, Zeldin DC. Enhanced postischemic functional recovery in CYP2J2 transgenic hearts involves mitochondrial ATP-sensitive K channels and p42/p44 MAPK pathway. Circ Res. 2004;95:506 –514. Seubert JM, Zeldin DC, Nithipatikom K, Gross GJ. Role of epoxyeicosatrienoic acids in protecting the myocardium following ischemia/ reperfusion injury. Prostaglandins Other Lipid Mediat. 2007;82:50 –59. Gross GJ, Hsu A, Falck JR, Nithipatikom K. Mechanisms by which epoxyeicosatrienoic acids (EETs) elicit cardioprotection in rat hearts. J Mol Cell Cardiol. 2007;42:687– 691.

21. Oparil S, Yarows SA, Patel S, Fang H, Zhang J, Satlin A. Efficacy and safety of combined use of aliskiren and valsartan in patients with hypertension: a randomised, double-blind trial. Lancet. 2007;370:221–229. 22. Delpon E, Caballero R, Gomez R, Nunez L, Tamargo J. Angiotensin II, angiotensin II antagonists and spironolactone and their modulation of cardiac repolarization. Trends Pharmacol Sci. 2005;26:155–161. 23. Struthers AD, MacDonald TM. Review of aldosterone- and angiotensin II-induced target organ damage and prevention. Cardiovasc Res. 2004; 61:663– 670. 24. von Schacky C, Baumann K, Angerer P. The effect of n-3 fatty acids on coronary atherosclerosis: results from SCIMO, an angiographic study, background and implications. Lipids. 2001;36:S99 –S102. 25. Marchioli R, Barzi F, Bomba E, Chieffo C, Di Gregorio D, Di Mascio R, Franzosi MG, Geraci E, Levantesi G, Maggioni AP, Mantini L, Marfisi RM, Mastrogiuseppe G, Mininni N, Nicolosi GL, Santini M, Schweiger C, Tavazzi L, Tognoni G, Tucci C, Valagussa F. Early protection against sudden death by n-3 polyunsaturated fatty acids after myocardial infarction: time-course analysis of the results of the Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto Miocardico (GISSI)Prevenzione. Circulation. 2002;105:1897–1903. 26. Calo L, Bianconi L, Colivicchi F, Lamberti F, Loricchio ML, de Ruvo E, Meo A, Pandozi C, Staibano M, Santini M. N-3 Fatty acids for the prevention of atrial fibrillation after coronary artery bypass surgery: a randomized, controlled trial. J Am Coll Cardiol. 2005;45:1723–1728. 27. Xiao HD, Fuchs S, Campbell DJ, Lewis W, Dudley SC Jr, Kasi VS, Hoit BD, Keshelava G, Zhao H, Capecchi MR, Bernstein KE. Mice with cardiac-restricted angiotensin-converting enzyme (ACE) have atrial enlargement, cardiac arrhythmia, and sudden death. Am J Pathol. 2004; 165:1019 –1032. 28. Ouvrard-Pascaud A, Sainte-Marie Y, Benitah JP, Perrier R, Soukaseum C, Cat AN, Royer A, Le Quang K, Charpentier F, Demolombe S, Mechta-Grigoriou F, Beggah AT, Maison-Blanche P, Oblin ME, Delcayre C, Fishman GI, Farman N, Escoubet B, Jaisser F. Conditional mineralocorticoid receptor expression in the heart leads to life-threatening arrhythmias. Circulation. 2005;111:3025–3033. 29. Domenighetti AA, Boixel C, Cefai D, Abriel H, Pedrazzini T. Chronic angiotensin II stimulation in the heart produces an acquired long QT syndrome associated with IK1 potassium current downregulation. J Mol Cell Cardiol. 2007;42:63–70. 30. Kasi VS, Xiao HD, Shang LL, Iravanian S, Langberg J, Witham EA, Jiao Z, Gallego CJ, Bernstein KE, Dudley SC Jr. Cardiac-restricted angioten-







37. 38.




Downloaded from hyper.ahajournals.org by on March 16, 2011

英文疾病介绍——Hypertension_临床医学_医药卫生_专业资料。高血压病——英文疾病介绍 Hypertension 高血压病 What Is Hypertension? ? Hypertension (HTN) is a ...
高血压护理常规 - 第十节 一、定义 原发性高血压护理 原发性高血压(primary hypertension)是以体循环动脉压升高为主要临床 表现的心血管综合征, 通常简称高血压...
高血压英语怎么说_英语学习_外语学习_教育专区。高血压英语怎么说高血压英语怎么说高血压英语怎么说 hypertension high blood pressure 高血压相关英语词汇: blood-pres...
高血压与跌倒_临床医学_医药卫生_专业资料。高血压与跌倒书本资料一.高血压的定义: 高血压(hypertension):是一种常见的以体循环动脉压增高为主的临床症候群,是最...
单纯收缩期高血压多见单纯收缩期高血压 (isolated systolic hypertension, ISH)的患病率随年龄的增长而增加,据美 国老龄人群的收缩期高血压项目研究 (Systolic ...
高血压_临床医学_医药卫生_专业资料。老年高血压患者非药物治疗依从性的研究性状 高倩 摘要 老年人高血压(old-people's hypertension)作为慢性病的一种, 其治疗和...
高血压_临床医学_医药卫生_专业资料。高血压病的治疗专题讲座 授课人:龚忠厚 高血压病(hypertension) 是指成人(≥18 岁)在安静状态下动脉收缩压≥140mmHg(18.7...
关键词:高血压发病机理 1.高血压 1.1 概述高血压(hypertension)是指以体循环动脉血压(收缩压和/或舒张压)增高 为主要特征(按照世界卫生组织(WHO)建议使用的血压...
Key words Hypertension;Treatment status;Living guidance 根据 2005 年《中国高血压防治指南》,我国高血压的诊断标准为:在未服用降压药物的 情况下,收缩压≥140...
(ACC)和美国疾病 预防与控制中心(CDC)共同制定的《有效控制高血压的科学建议》 (以下简称《建议》)于 2013 年 11 月 15 日在高血压杂志 (Hypertension)在线...