Increasing mitochondrial ATP synthesis with butyrate normalizes ADP and contractile function in metabolic heart disease.

Metabolic heart disease (MHD), which is strongly associated with heart failure with preserved ejection fraction, is characterized by reduced mitochondrial energy production and contractile performance. In this study, we tested the hypothesis that an acute increase in ATP synthesis, via short chain fatty acid (butyrate) perfusion, restores contractile function in MHD. Isolated hearts of mice with MHD due to consumption of a high fat high sucrose (HFHS) diet or on a control diet (CD) for 4 months were studied using 31 P NMR spectroscopy to measure high energy phosphates and ATP synthesis rates during increased work demand. At baseline, HFHS hearts had increased ADP and decreased free energy of ATP hydrolysis (ΔG~ATP ), although contractile function was similar between the two groups. At high work demand, the ATP synthesis rate in HFHS hearts was reduced by over 50%. Unlike CD hearts, HFHS hearts did not increase contractile function at high work demand, indicating a lack of contractile reserve. However, acutely supplementing HFHS hearts with 4mM butyrate normalized ATP synthesis, ADP, ΔG~ATP and contractile reserve. Thus, acute reversal of depressed mitochondrial ATP production improves contractile dysfunction in MHD. These findings suggest that energy starvation may be a reversible cause of myocardial dysfunction in MHD, and opens new therapeutic opportunities.

Benefit-Risk Assessment of Crataegus Extract WS 1442: An Evidence-Based Review.

Preparations from Crataegus (hawthorn) have a long history in the treatment of heart failure. WS 1442 is a dry extract from hawthorn leaves with flowers (4-6.6:1), extraction solvent of ethanol 45% (w/w), adjusted to 17.3-20.1% of oligomeric procyanidins. Nonclinical studies show that WS 1442 has positive inotropic and antiarrhythmic properties and protects the myocardium from ischemic damage, reperfusion injury, and hypertension-related hypertrophy, improves endothelial functions such as NO synthesis, and delays endothelial senescence. Randomized, controlled trials in patients with heart failure have demonstrated that the herbal medicinal product increases functional capacity, alleviates disabling symptoms, and improves health-related quality of life, all of which have become important targets of heart failure therapy according to current disease management guidelines. Clinical trials (including a 2-year mortality study with polypharmacy and > 1300 patients exposed) and post-marketing surveillance studies have shown that WS 1442 has a very favorable safety profile both as monotherapy and as add-on therapy, where no drug interactions have been observed. No specific adverse reactions to WS 1442 are known to date. WS 1442 may thus help to close the therapeutic gap between systolic and diastolic heart failure for which evidence of efficacy for other cardioactive drugs is sparse. Scientific evidence shows that WS 1442 is safe and has a beneficial effect in patients with heart failure corresponding to New York Heart Association classes II or III. The benefit-risk assessment for WS 1442 is therefore positive.

The efficacy and safety of Crataegus extract WS 1442 in patients with heart failure: the SPICE trial.

BACKGROUND: Crataegus preparations have been used for centuries especially in Europe. To date, no proper data on their efficacy and safety as an add-on-treatment are available. Therefore a large morbidity/mortality trial was performed. AIM: To investigate the efficacy and safety of an add-on treatment with Crataegus extract WS 1442 in patients with congestive heart failure. METHODS: In this randomised, double-blind, placebo-controlled multicenter study, adults with NYHA class II or III CHF and reduced left ventricular ejection fraction (LVEF< or =35%) were included and received 900 mg/day WS 1442 or placebo for 24 months. Primary endpoint was time until first cardiac event. RESULTS: 2681 patients (WS 1442: 1338; placebo: 1343) were randomised. Average time to first cardiac event was 620 days for WS 1442 and 606 days for placebo (event rates: 27.9% and 28.9%, hazard ratio (HR): 0.95, 95% CI [0.82;1.10]; p=0.476). The trend for cardiac mortality reduction with WS 1442 (9.7% at month 24; HR: 0.89 [0.73;1.09]) was not statistically significant (p=0.269). In the subgroup with LVEF> or =25%, WS 1442 reduced sudden cardiac death by 39.7% (HR 0.59 [0.37;0.94] at month 24; p=0.025). Adverse events were comparable in both groups. CONCLUSIONS: In this study, WS 1442 had no significant effect on the primary endpoint. WS 1442 was safe to use in patients receiving optimal medication for heart failure. In addition, the data may indicate that WS 1442 can potentially reduce the incidence of sudden cardiac death, at least in patients with less compromised left ventricular function.

Mineralocorticoid receptor inhibition ameliorates the transition to myocardial failure and decreases oxidative stress and inflammation in mice with chronic pressure overload.

BACKGROUND: Although aldosterone, acting via mineralocorticoid receptors, causes left ventricular (LV) hypertrophy in experimental models of high-aldosterone hypertension, little is known about the role of aldosterone or mineralocorticoid receptors in mediating adverse remodeling in response to chronic pressure overload. METHODS AND RESULTS: We used the mineralocorticoid receptor-selective antagonist eplerenone (EPL) to test the role of mineralocorticoid receptors in mediating the transition from hypertrophy to failure in mice with chronic pressure overload caused by ascending aortic constriction (AAC). One week after AAC, mice were randomized to regular chow or chow containing EPL (200 mg/kg per day) for an additional 7 weeks. EPL had no significant effect on systolic blood pressure after AAC. Eight weeks after AAC, EPL treatment improved survival (94% versus 65%), attenuated the increases in LV end-diastolic (3.4+/-0.1 versus 3.7+/-0.1 mm) and end-systolic (2.0+/-0.1 versus 2.5+/-0.2 mm) dimensions, and ameliorated the decrease in fractional shortening (42+/-2% versus 34+/-4%). EPL also decreased myocardial fibrosis, myocyte apoptosis, and the ratio of matrix metalloproteinase-2/tissue inhibitor of matrix metalloproteinase-2. These beneficial effects of EPL were associated with less myocardial oxidative stress, as assessed by 3-nitrotyrosine staining, reduced expression of the adhesion molecule intercellular adhesion molecule-1, and reduced infiltration by macrophages. CONCLUSIONS: Mineralocorticoid receptors play an important role in mediating the transition from LV hypertrophy to failure with chronic pressure overload. The effects of mineralocorticoid receptor stimulation are associated with alterations in the interstitial matrix and myocyte apoptosis and may be mediated, at least in part, by oxidative stress and inflammation.

Statins inhibit beta-adrenergic receptor-stimulated apoptosis in adult rat ventricular myocytes via a Rac1-dependent mechanism.

BACKGROUND: 3-hydroxy-3-methylglutaryl coenzyme A inhibitors (statins) inhibit myocyte hypertrophy in vitro and ameliorate the progression of cardiac remodeling in vivo, possibly because of inhibition of the small GTPase Rac1. The role of Rac1 in mediating myocyte apoptosis is not known. beta-Adrenergic receptor (betaAR)-stimulated myocyte apoptosis is mediated via activation of c-Jun NH2-terminal kinase (JNK), leading to activation of the mitochondrial death pathway. We hypothesized that betaAR-stimulated apoptosis in adult rat ventricular myocyte (ARVMs) is mediated by Rac1 and inhibited by statins. METHODS AND RESULTS: betaAR stimulation increased apoptosis, as assessed by transferase-mediated nick-end labeling, from 5+/-1% to 24+/-2%. betaAR stimulation also increased Rac1 activity. Adenoviral overexpression of a dominant-negative mutant of Rac1 inhibited betaAR-stimulated apoptosis, JNK activation, cytochrome C release, and caspase-3 activation. Cerivastatin likewise inhibited the betaAR-stimulated activation of Rac1, decreased betaAR-stimulated apoptosis to 11+/-2%, and inhibited JNK activation, cytochrome C release, and caspase-3 activation. CONCLUSIONS: betaAR stimulation causes Rac1 activation, which is required for myocyte apoptosis and leads to activation of JNK and the mitochondrial death pathway. Cerivastatin inhibits betaAR-stimulated activation of Rac1 and thereby inhibits JNK-dependent activation of the mitochondrial death pathway and apoptosis. The beneficial effects of statins on the myocardium may be mediated in part via inhibition of Rac1-dependent myocyte apoptosis.

Myocyte contractile activity modulates norepinephrine cytotoxicity and survival effects of neuregulin-1beta.

The purpose of this study is to test the hypothesis that mechanical and electrical activity in adult rat ventricular myocytes (ARVM) alters responses to proapoptotic and prosurvival ligands. The effects of electrical stimulation on myocyte survival, stress signaling, response to beta-adrenergic receptor (beta-AR)-stimulated apoptosis, and neuregulin-1beta (NRG) were examined. Electrical stimulation (6.6 V/cm; 0, 2, and 5 Hz; 2-ms duration; alternating polarity) of ARVM resulted in more than 70% capture. Although ARVM paced for 48 h showed higher mitochondrial uptake of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (P < 0.05, 0 vs. 2 and 5 Hz), electrical stimulation had little effect on cell survival assessed by trypan blue uptake, CPK release, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining. Electrical stimulation for 24 h did not induce stress response (heat shock protein 70, 90) nor stress kinase (Erk, JNK, p38) activation. NRG stimulation of Erk and Akt was similar between paced and quiescent cells. Pacing sensitized myocytes to beta-AR-stimulated JNK phosphorylation and cell death with 0.1 microM norepinephrine (NE) in paced myocytes causing equivalent cytotoxicity to 10 microM NE in quiescent cells. NRG suppressed beta-AR-induced apoptosis through a phosphatidylinositol-3-kinase-dependent pathway in both paced and quiescent cells, although it is overwhelmed by high-NE concentration in paced cells. Thus myocyte contractility modulates both NE cytotoxicity as well as the cytoprotective effect of NRG. These results demonstrate the feasibility and importance of using electrically paced cardiomyocytes in primary culture when examining the signaling pathways of cell survival.