The sympathetic nervous system in heart failure physiology, pathophysiology, and clinical implications

Current status of mechanical circulatory support: a systematic review

Heart failure is a major public health problem and its management requires a significant amount of health care resources. Even with administration of the best available medical treatment, the mortality associated with the disease remains high. As therapeutical strategies for heart failure have been refined, the number of patients suffering from the disease has expanded dramatically. Although heart transplantation still represents the gold standard therapeutical approach, the implantation of mechanical circulatory support devices (MCSDs) evolved to a well-established management for this disease. The limited applicability of heart transplantation caused by a shortage of donor organs and the concurrent expand of the patient population with end-stage heart failure led to a considerable utilization of MCSDs. This paper outlines the current status of mechanical circulatory support.

Extracardiac neural remodeling in humans with cardiomyopathy

BACKGROUND

Intramyocardial nerve sprouting after myocardial infarction is associated with ventricular arrhythmias. Whether human stellate ganglia remodel in association with cardiac pathology is unknown. The purpose of this study was to determine whether cardiac pathology is associated with remodeling of the stellate ganglia in humans.

METHODS AND RESULTS

Left stellate ganglia were collected from patients undergoing sympathetic denervation for intractable ventricular arrhythmias and from cadavers, along with intact hearts. Clinical data on patients and cadaveric subjects were reviewed. We classified ganglia from normal, scarred, and nonischemic cardiomyopathic hearts without scar as NL (n=3), SCAR (n=24), and NICM (n=7), respectively. Within left stellate ganglia, neuronal size, density, fibrosis, synaptic density, and nerve sprouting were determined. Nerve density and sprouting were also quantified in cadaveric hearts. Mean neuronal size in normal, scarred, and nonischemic cardiomyopathic hearts without scar groups were 320 ± 4 μm(2), 372 ± 10 μm(2), and 435 ± 10 μm(2) (P=0.002), respectively. No significant differences in neuronal density and fibrosis were present between the groups. Synaptic density in ganglia from SCAR and NICM groups were 57.8 ± 11.2 μm(2)/mm(2) (P=0.084) and 44.5 ± 7.9 μm(2)/mm(2) (P=0.039), respectively, compared with the normal group, 17.8 ± 7 μm(2)/mm(2) (overall P=0.162). There were no significant differences in left stellate ganglia nerve sprouting or myocardial nerve density between the groups.

CONCLUSIONS

Neuronal hypertrophy within left stellate ganglia is associated with chronic cardiomyopathy in humans. Ganglionic and myocardial nerve sprouting and nerve density were not significantly different. These changes may be related to increased cardiac sympathetic signaling and ventricular arrhythmias. Further studies are needed to determine the electrophysiological consequences of extracardiac neuronal remodeling in humans.

Direct cardiac toxicity of the tentacle-only extract from the jellyfish Cyanea capillata demonstrated in isolated rat heart

Previous studies in our laboratory have shown that the cardiotoxicity is the main reason for rat death caused by tentacle-only extract from jellyfish Cyanea capillata. However, the direct cardiotoxicity in vitro and its mechanisms of toxic action remain unclear. The current studies were performed by using the Langendorff-perfused isolated heart model, which showed a dose-dependent hemodynamic and electrocardiogram changes. Heart injury-related enzymes increased. Histopathological analysis showed early ischemic damage in the myocardium. The Ca channel blockers nifedipine and verapamil led to a marked improvement in recovery of cardiac function, including heart rate, left ventricular developed pressure, positive and negative first derivatives of intraventricular pressure, coronary flow, left ventricular end-diastolic pressure, and electrocardiogram changes. Tentacle-only extract-induced cardiac dysfunction could be partly improved by the pretreatments of both propranolol and phentolamine, but not by either atropine or neostigmine at all. In conclusion, we have verified the direct cardiotoxicity of tentacle-only extract from jellyfish C. capillata by the Langendorff isolated heart model, which consisted of 3 separate parts: sinoatrial node malfunction, cardiomyocyte injury, and coronary spasm. The potential mechanism might be attributed to the overactivation of L-type Ca channel, β- and α-adrenergic receptors, but not cholinergic receptors.

Central mechanisms of abnormal sympathoexcitation in chronic heart failure

It has been recognized that the sympathetic nervous system is abnormally activated in chronic heart failure, and leads to further worsening chronic heart failure. In the treatment of chronic heart failure many clinical studies have already suggested that the inhibition of the abnormal sympathetic hyperactivity by beta blockers is beneficial. It has been classically considered that abnormal sympathetic hyperactivity in chronic heart failure is caused by the enhancement of excitatory inputs including changes in peripheral baroreceptor and chemoreceptor reflexes and chemical mediators that control sympathetic outflow. Recently, the abnormalities in the central regulation of sympathetic nerve activity mediated by brain renin angiotensin system-oxidative stress axis and/or proinflammatory cytokines have been focused. Central renin angiotensin system, proinflammatory cytokines, and the interaction between them have been determined as the target of the sympathoinhibitory treatment in experimental animal models with chronic heart failure. In conclusion, we must recognize that chronic heart failure is a syndrome with an abnormal sympathoexcitation, which is caused by the abnormalities in the central regulation of sympathetic nerve activity.

Blockade of β-adrenoceptors restores the GRK2-mediated adrenal α(2) -adrenoceptor-catecholamine production axis in heart failure

BACKGROUND AND PURPOSE

Sympathetic nervous system (SNS) hyperactivity is characteristic of chronic heart failure (HF) and significantly worsens prognosis. The success of β-adrenoceptor antagonist (β-blockers) therapy in HF is primarily attributed to protection of the heart from the noxious effects of augmented catecholamine levels. β-Blockers have been shown to reduce SNS hyperactivity in HF, but the underlying molecular mechanisms are not understood. The GPCR kinase-2 (GRK2)-α(2) adrenoceptor-catecholamine production axis is up-regulated in the adrenal medulla during HF causing α(2) -adrenoceptor dysfunction and elevated catecholamine levels. Here, we sought to investigate if β-blocker treatment in HF could lower SNS activation by directly altering adrenal GRK2 levels.

EXPERIMENTAL APPROACH

Four weeks after myocardial infarction-induced HF, adult rats were randomized to 10-week treatment with vehicle (HF/C) or bisoprolol (HF/B). Cardiac function and dimensions were measured. In heart and adrenal gland, GRK2 levels were assessed by RT-PCR and Western blotting and adrenoceptors studied with radioligand binding. Catecholamines and α(2) adrenoceptors in adrenal medulla chromaffin cell cultures were also measured.

KEY RESULTS

Bisoprolol treatment ameliorated HF-related adverse cardiac remodelling and reduced plasma catecholamine levels, compared with HF/C rats. Bisoprolol also attenuated adrenal GRK2 overexpression as observed in HF/C rats and increased α(2) adrenoceptor density. In cultures of adrenal medulla chromaffin cells from all study groups, bisoprolol reversed HF-related α(2) adrenoceptor dysfunction. This effect was reversed by GRK2 overexpression.

CONCLUSION AND IMPLICATIONS

Blockade of β-adrenoceptors normalized the adrenal α(2) adrenoceptor-catecholamine production axis by reducing GRK2 levels. This effect may contribute significantly to the decrease of HF-related sympathetic overdrive by β-blockers.

Myocardial β(2) -adrenoceptor gene delivery promotes coordinated cardiac adaptive remodelling and angiogenesis in heart failure

BACKGROUND AND PURPOSE

We investigated whether β(2) -adrenoceptor overexpression could promote angiogenesis and improve blood perfusion and left ventricular (LV) remodeling of the failing heart.

EXPERIMENTAL APPROACH

We explored the angiogenic effects of β(2) -adrenoceptor overexpression in a rat model of post-myocardial infarction (MI) heart failure (HF). Cardiac adenoviral-mediated β(2) -adrenoceptor overexpression was obtained via direct intramyocardial injection 4-weeks post-MI. Adenovirus(Ad)-GFP and saline injected rats served as controls. Furthermore, we extended our observation to β(2) -adrenoceptor -/- mice undergoing MI.

KEY RESULTS

Transgenes were robustly expressed in the LV at 2 weeks post-gene therapy, whereas their expression was minimal at 4-weeks post-gene delivery. In HF rats, cardiac β(2) -adrenoceptor overexpression resulted in enhanced basal and isoprenaline-stimulated cardiac contractility at 2-weeks post-gene delivery. At 4 weeks post-gene transfer, Ad-β(2) -adrenoceptor HF rats showed improved LV remodeling and cardiac function. Importantly, β(2) -adrenoceptor overexpression was associated with a markedly increased capillary and arteriolar length density and enhanced in vivo myocardial blood flow and coronary reserve. At the molecular level, cardiac β(2) -adrenoceptor gene transfer induced the activation of the VEGF/PKB/eNOS pro-angiogenic pathway. In β(2) -adrenoceptor-/- mice, we found a ~25% reduction in cardiac capillary density compared with β(2) -adrenoceptor+/+ mice. The lack of β(2) -adrenoceptors was associated with a higher mortality rate at 30 days and LV dilatation, and a worse global cardiac contractility compared with controls.

CONCLUSIONS AND IMPLICATION

β(2) -Adrenoceptors play an important role in the regulation of the angiogenic response in HF. The activation of VEGF/PKB/eNOS pathway seems to be strongly involved in this mechanism.

The wonders of the Wanderer

Vagus is Latin for wandering, and the vagus nerve fully deserves this name due to its extensive distribution through the body. Indeed, one of the lines of the song that accompanied the 2012 G. L. Brown Prize Lecture exaggerates this diversity, 'My function's almost anythin', and vagus is my name'. Alteration of vagal activity was first investigated in the 1880s as a treatment for epilepsy, and vagus nerve stimulation is now an approved treatment for refractory epilepsy and depression in the USA, despite an incomplete understanding of the mechanisms involved. Vagus nerve stimulation could be beneficial in many other conditions, including heart failure, tinnitus, chronic hiccups, Alzheimer's disease and inflammatory diseases. Inhibition of vagal activity could also be beneficial in some conditions, e.g. reducing activation of vagal respiratory afferents to treat chronic cough. This review discusses evidence underlying some current and potential therapeutic applications of vagal modulation, illustrating the wonders of the Wanderer.

Cardiorenal syndrome type 1: pathophysiological crosstalk leading to combined heart and kidney dysfunction in the setting of acutely decompensated heart failure

Cardiorenal syndrome (CRS) type 1 is characterized as the development of acute kidney injury (AKI) and dysfunction in the patient with acute cardiac illness, most commonly acute decompensated heart failure (ADHF). There is evidence in the literature supporting multiple pathophysiological mechanisms operating simultaneously and sequentially to result in the clinical syndrome characterized by a rise in serum creatinine, oliguria, diuretic resistance, and in many cases, worsening of ADHF symptoms. The milieu of chronic kidney disease has associated factors including obesity, cachexia, hypertension, diabetes, proteinuria, uremic solute retention, anemia, and repeated subclinical AKI events all work to escalate individual risk of CRS in the setting of ADHF. All of these conditions have been linked to cardiac and renal fibrosis. In the hospitalized patient, hemodynamic changes leading to venous renal congestion, neurohormonal activation, hypothalamic-pituitary stress reaction, inflammation and immune cell signaling, systemic endotoxemic exposure from the gut, superimposed infection, and iatrogenesis all contribute to CRS type 1. The final common pathway of bidirectional organ injury appears to be cellular, tissue, and systemic oxidative stress that exacerbate organ function. This review explores in detail the pathophysiological pathways that put a patient at risk and then effectuate the vicious cycle now recognized as CRS type 1.

Conducting the G-protein Coupled Receptor (GPCR) Signaling Symphony in Cardiovascular Diseases: New Therapeutic Approaches

G protein-coupled receptors (GPCRs) are a virtually ubiquitous class of membrane-bound receptors, which functionally couple hormone or neurotransmitter signals to physiological responses. Dysregulation of GPCR signaling contributes to the pathophysiology of a host of cardiovascular disorders. Pharmacological agents targeting GPCRs have been established as therapeutic options for decades. Nevertheless, the persistent burden of cardiovascular diseases necessitates improved treatments. To that end, exciting drug development efforts have begun to focus on novel compounds that discriminately activate particular GPCR signaling pathways.

Different expression of adrenoceptors and GRKs in the human myocardium depends on heart failure etiology and correlates to clinical variables

Downregulation of β(1)- adrenergic receptors (β(1)-ARs) and increased expression/function of G-protein-coupled receptor kinase 2 (GRK2) have been observed in human heart failure, but changes in expression of other ARs and GRKs have not been established. Another unresolved question is the incidence of these compensatory mechanisms depending on heart failure etiology and treatment. To analyze these questions, we quantified the mRNA/protein expressions of six ARs (α(1A), α(1B), α(1D), β(1), β(2), and β(3)) and three GRKs (GRK2, GRK3, and GRK5) in left (LV) and right ventricle (RV) from four donors, 10 patients with ischemic cardiomyopathy (IC), 14 patients with dilated cardiomyopathy (DC), and 10 patients with nonischemic, nondilated cardiopathies (NINDC). We correlated the changes in the expressions of ARs and GRKs with clinical variables such as left ventricular ejection fraction (LVEF) and left ventricular end-systolic and left ventricular end-diastolic diameter (LVESD and LVEDD, respectively). The main findings were 1) the expression of the α(1A)-AR in the LV positively correlates with LVEF; 2) the expression of GRK3 and GRK5 inversely correlates with LVESD and LVEDD, supporting previous observations about a protective role for both kinases in failing hearts; and 3) β(1)-AR expression is downregulated in the LV and RV of IC, in the LV of DC, and in the RV of NINDC. This difference, better than an increased expression of GRK2 (not observed in IC), determines the lower LVEF in IC and DC vs. NINDC.

Telemonitoring in chronic heart failure: a systematic review

Heart failure (HF) is a growing epidemic with the annual number of hospitalizations constantly increasing over the last decades for HF as a primary or secondary diagnosis. Despite the emergence of novel therapeutic approached that can prolong life and shorten hospital stay, HF patients will be needing rehospitalization and will often have a poor prognosis. Telemonitoring is a novel diagnostic modality that has been suggested to be beneficial for HF patients. Telemonitoring is viewed as a means of recording physiological data, such as body weight, heart rate, arterial blood pressure, and electrocardiogram recordings, by portable devices and transmitting these data remotely (via a telephone line, a mobile phone or a computer) to a server where they can be stored, reviewed and analyzed by the research team. In this systematic review of all randomized clinical trials evaluating telemonitoring in chronic HF, we aim to assess whether telemonitoring provides any substantial benefit in this patient population.

Cognitive impairment in heart failure

Cognitive impairment (CI) is increasingly recognized as a common adverse consequence of heart failure (HF). Although the exact mechanisms remain unclear, microembolism, chronic or intermittent cerebral hypoperfusion, and/or impaired cerebral vessel reactivity that lead to cerebral hypoxia and ischemic brain damage seem to underlie the development of CI in HF. Cognitive decline in HF is characterized by deficits in one or more cognition domains, including attention, memory, executive function, and psychomotor speed. These deficits may affect patients' decision-making capacity and interfere with their ability to comply with treatment requirements, recognize and self-manage disease worsening symptoms. CI may have fluctuations in severity over time, improve with effective HF treatment or progress to dementia. CI is independently associated with disability, mortality, and decreased quality of life of HF patients. It is essential therefore for health professionals in their routine evaluations of HF patients to become familiar with assessment of cognitive performance using standardized screening instruments. Future studies should focus on elucidating the mechanisms that underlie CI in HF and establishing preventive strategies and treatment approaches.

Association Between Epicardial Fat Thickness and Weight Homeostasis Hormones in Patients With Noncachectic Heart Failure

The relationship between echocardiographically measured epicardial fat thickness (EFT) and plasma concentrations of leptin, ghrelin, and adiponectin has not been evaluated in patients with noncachectic heart failure (HF). Patients with noncachectic HF and age- and sex-matched controls did not differ significantly in EFT, whereas EFT values showed significant positive correlation with body mass index (BMI) in both groups and were negatively related with brain natriuretic peptide and positively with log leptin values in the HF group. In the control group, a positive correlation with high-sensitivity C-reactive protein (hsCRP) and a negative correlation with log ghrelin were found. In multivariable analysis, log leptin was a significant predictor of EFT in patients with HF, but this effect was not retained after adjusting for BMI. In contrast, log ghrelin and hsCRP were significant predictors of EFT in controls even after adjusting for BMI.

Cardiorenal syndrome in acute decompensated heart failure

Cardiorenal syndrome (CRS) commonly occurs during treatment of acute decompensated heart failure (ADHF) and is associated with poor clinical outcome. The pathophysiology of CRS entails a complex interaction between hemodynamic alterations, including reduced renal perfusion, increased venous pressure and activation of multiple neurohormonal systems. Attempts to effectively treat congestion while preserving renal function in ADHF are often met with limited clinical success and often require therapeutic decisions that reflect a compromise between potential benefits and harm. At present, there is no evidence-based intervention specifically targeted at renal function. Recent Phase III randomized trials, using novel agents in patients with ADHF, have largely failed to demonstrate any benefits of therapy on renal and clinical outcomes. Early diagnosis of CRS using novel markers of tubular injury may allow for timely interventions and attenuate progression. Future studies are needed to further elucidate the pathophysiology of this complex syndrome and identify new potential targets for effective evidence-based treatments.

Mending injured endothelium in chronic heart failure: a new target for exercise training

The recognition that poor cardiac performance is not the sole determinant of exercise intolerance in CHF patients has altered the target of exercise training. Endothelial dysfunction impairs exercise-induced vasodilation, thereby limiting oxygen supply to working muscles and increasing ventricular afterload. Since the 1990s, it has become clear that partial correction of this maladaptive reaction is a premise for the success of exercise training. Growing evidence indicates that increased NO bioavailability and reduction in oxidative stress result from regular physical activity. However, the basic concept of endothelial dysfunction has shifted from a pure "damage model" to a more dynamic process in which endothelial repair fails to keep pace with local injury. Indeed, recent evidence indicates that endothelial progenitor cells (EPC) and circulating angiogenic cells (CAC) contribute substantially to preservation of a structurally and functionally intact endothelium. In chronic heart failure, however, these endogenous repair mechanisms appear to be disrupted. In this review, we aim to give an overview on what is currently known about the influence of physical exercise on recruitment of EPC and activation of CAC in this particular patient group.

A novel player in cellular hypertrophy: Giβγ/PI3K-dependent activation of the RacGEF TIAM-1 is required for α₁-adrenoceptor induced hypertrophy in neonatal rat cardiomyocytes

Activation of α(1)-adrenoceptors (α(1)-AR) by high catecholamine levels, e.g. in heart failure, is thought to be a driving force of cardiac hypertrophy. In this context several downstream mediators and cascades have been identified to potentially play a role in cardiomyocyte hypertrophy. One of these proteins is the monomeric G protein Rac1. However, until now it is unclear how this essential G protein is activated by α(1)-AR agonists and what are the downstream targets inducing cellular growth. By using protein-based as well as pharmacological inhibitors and the shRNA technique, we demonstrate that in neonatal rat cardiomyocytes (NRCM) Rac1 is activated via a cascade involving the α(1A)-AR subtype, G(i)βγ, the phosphoinositide-3'-kinase and the guanine nucleotide exchange factor Tiam1. We further demonstrate that this signaling induces an increase in protein synthesis, cell size and atrial natriuretic peptide expression. We identified the p21-activated kinase 2 (PAK2) as a downstream effector of Rac1 and were able to link this cascade to the activation of the pro-hypertrophic kinases ERK1/2 and p90RSK. Our data thus reveal a prominent role of the α(1A)-AR/G(i)βγ/Tiam1-mediated activation of Rac1 and its effector PAK2 in the induction of hypertrophy in NRCM.

A general theory of acute and chronic heart failure

Current concepts of heart failure propose multiple heterogeneous pathophysiological mechanisms. Recently a theoretical framework for understanding chronic heart failure was suggested. This paper develops this framework to include acute heart failure syndromes. We propose that all acute heart failure syndromes may be understood in terms of a relative fall in left ventricular stroke volume. The initial compensatory mechanism is frequently a tachycardia often resulting in a near normal cardiac output. In more severe forms a fall in cardiac output causes hypotension or cardiogenic shock. In chronic heart failure the stroke volume and cardiac output is returned to normal predominantly through ventricular remodeling or dilatation. Ejection fraction is simply the ratio of stroke volume and end-diastolic volume. The resting stroke volume is predetermined by the tissue's needs; therefore, if the ejection fraction changes, the end-diastolic volume must change in a reciprocal manner. The potential role of the right heart in influencing the presentation of left heart disease is examined. We propose that acute pulmonary edema occurs when the right ventricular stroke volume exceeds left ventricular stroke volume leading to fluid accumulation in the alveoli. The possible role of the right heart in determining pulmonary hypertension and raised filling pressures in left-sided heart disease are discussed. Different clinical scenarios are presented to help clarify these proposed mechanisms and the clinical implications of these theories are discussed. Finally an alternative definition of heart failure is proposed.

Association of in vivo β-adrenergic receptor sensitivity with inflammatory markers in healthy subjects

OBJECTIVE

Several stress-related states and conditions that are considered to involve sympathetic overactivation are accompanied by increased circulating levels of inflammatory immune markers. Prolonged sympathetic overactivity involves increased stimulation of the β-adrenergic receptor (β-AR). Although prior research suggests that one mechanism by which sympathetic stimulation may facilitate inflammation is via β-AR activation, little work has focused on the relationship between circulating inflammatory immune markers and β-AR function within the human body (in vivo). We examined whether decreased β-AR sensitivity, an indicator of prolonged β-adrenergic overactivation and a physiological component of chronic stress, is related to elevated levels of inflammatory immune markers.

METHODS

Ninety-three healthy participants aged 19 to 51 years underwent the chronotropic 25 dose isoproterenol test to determine in vivo β-AR function. Circulating levels of C-reactive protein, interleukin 6, and soluble tumor necrosis factor receptor 1 were determined.

RESULTS

β-AR sensitivity was lower in people with higher C-reactive protein concentrations (r = 0.326, p = .003). That relationship remained significant after controlling for sociodemographic and health variables such as age, sex, ethnicity, body mass index, mean arterial blood pressure, heart rate, leisure-time exercise, and smoking status. No significant relationship was found between chronotropic 25 dose and interleukin 6 or soluble tumor necrosis factor receptor 1.

CONCLUSIONS

This study demonstrates a link between in vivo β-adrenergic receptor function and selected circulating inflammatory markers (CRP) in humans. Future studies in specific disease states may be promising.

Cardiac applications of 123I-mIBG imaging

Cardiac autonomic innervation plays a key role in maintaining hemodynamic and electrophysiologic harmony. Cardiac sympathetic function is adversely altered in many disease states, such as congestive heart failure, myocardial ischemia, and diabetes. (123)I-mIBG, a sympathetic neurotransmitter radionuclide analog, aids in the detection of sympathetic innervation abnormalities and can be imaged with planar and single-photon emission computed tomographic techniques. Cardiac (123)I-mIBG uptake can be assessed by the heart mediastinal ratio (H/M), tracer washout rate, and focal uptake defects. These parameters have been widely studied and shown to correlate strongly and independently with congestive heart failure progression, cardiac arrhythmias, cardiac death, and all-cause mortality. There is accumulating evidence that (123)I-mIBG imaging can help to monitor a patient's clinical course and response to therapy. The ability to predict potentially lethal ventricular arrhythmias promises to help more accurately select patients for implantable cardioverter defibrillators, limiting unnecessary devices and identifying additional patients at risk who do not meet current guidelines. (123)I-mIBG shows potential to help determine whether greater risk and usually more expensive ventricular assist device therapies or cardiac transplantation might be needed. Although more investigation in larger populations is needed to strengthen previous findings, cardiac (123)I-mIBG imaging shows promise as a new technique for recognizing and following potentially life-threatening cardiac conditions.

Anemia in heart failure patients

Heart failure is a very common disease, with severe morbidity and mortality, and a frequent reason of hospitalization. Anemia and a concurrent renal impairment are two major risk factors contributing to the severity of the outcome and consist of the cardio renal anemia syndrome. Anemia in heart failure is complex and multifactorial. Hemodilution, absolute or functional iron deficiency, activation of the inflammatory cascade, and impaired erythropoietin production and activity are some pathophysiological mechanisms involved in anemia of the heart failure. Furthermore other concomitant causes of anemia, such as myelodysplastic syndrome and chemotherapy, may worsen the outcome. Based on the pathophysiology of cardiac anemia, there are several therapeutic options that may improve hemoglobin levels, tissues' oxygenation, and probably the outcome. These include administration of iron, erythropoiesis-stimulating agents, and blood transfusions but still the evidence provided for their use remains limited.

Hyperphosphorylation of the cardiac ryanodine receptor at serine 2808 is not involved in cardiac dysfunction after myocardial infarction

RATIONALE

Abnormal behavior of the cardiac ryanodine receptor (RyR2) has been linked to cardiac arrhythmias and heart failure (HF) after myocardial infarction (MI). It has been proposed that protein kinase A (PKA) hyperphosphorylation of the RyR2 at a single residue, Ser-2808, is a critical mediator of RyR dysfunction, depressed cardiac performance, and HF after MI.

OBJECTIVE

We used a mouse model (RyRS2808A) in which PKA hyperphosphorylation of the RyR2 at Ser-2808 is prevented to determine whether loss of PKA phosphorylation at this site averts post MI cardiac pump dysfunction.

METHODS AND RESULTS

MI was induced in wild-type (WT) and S2808A mice. Myocyte and cardiac function were compared in WT and S2808A animals before and after MI. The effects of the PKA activator Isoproterenol (Iso) on L-type Ca(2+) current (I(CaL)), contractions, and [Ca(2+)](I) transients were also measured. Both WT and S2808A mice had depressed pump function after MI, and there were no differences between groups. MI size was also identical in both groups. L type Ca(2+) current, contractions, Ca(2+) transients, and SR Ca(2+) load were also not significantly different in WT versus S2808A myocytes either before or after MI. Iso effects on Ca(2+) current, contraction, Ca(2+) transients, and SR Ca(2+) load were identical in WT and S2808A myocytes before and after MI at both low and high concentrations.

CONCLUSIONS

These results strongly support the idea that PKA phosphorylation of RyR-S2808 is irrelevant to the development of cardiac dysfunction after MI, at least in the mice used in this study.

Evaluation of costs associated with tolvaptan-mediated length-of-stay reduction among heart failure patients with hyponatremia in the US, based on the EVEREST trial

BACKGROUND

The Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study with Tolvaptan (EVEREST) trial showed that tolvaptan use improved heart failure (HF) signs and symptoms without serious adverse events.

OBJECTIVE

To evaluate the potential cost savings associated with tolvaptan usage among hospitalized hyponatremic HF patients.

METHODS

The Healthcare Cost and Utilization Project (HCUP) 2008 Nationwide Inpatient Sample (NIS) database was used to estimate hospital cost and length of stay (LOS), for diagnosis-related group (DRG) hospitalizations of adult (age ≥18 years) HF patients with complications and comorbidities or major complications and comorbidities. EVEREST trial data for patients with hyponatremia were used to estimate tolvaptan-associated LOS reductions. A cost offset model was constructed to evaluate the impact of tolvaptan on hospital cost and LOS, with univariate and multivariate Monte Carlo sensitivity analyses.

RESULTS

Tolvaptan use among hyponatremic EVEREST trial HF patients was associated with shorter hospital LOS than placebo patients (9.72 vs 11.44 days, respectively); 688,336 hospitalizations for HF DRGs were identified from the HCUP NIS database, with a mean LOS of 5.4 days and mean total hospital costs of $8415. Using an inpatient tolvaptan treatment duration of 4 days with a wholesale acquisition cost of $250 per day, the cost offset model estimated a LOS reduction among HF hospitalizations of 0.81 days and an estimated total cost saving of $265 per admission. Univariate and multivariate sensitivity analysis demonstrated that cost reduction associated with tolvaptan usage is consistent among variations of model variables.

CONCLUSIONS

The estimated LOS reduction and cost savings projected by the cost offset model suggest a clinical and economic benefit to tolvaptan use in hyponatremic HF patients.

STUDY LIMITATIONS

The EVEREST trial data may not generalize well to the US population. Clinical trial patient profiles and relative LOS reductions may not be applicable to real-world patient populations.

Bisoprolol delays progression towards right heart failure in experimental pulmonary hypertension

BACKGROUND

In pulmonary arterial hypertension (PH), sympathetic adrenergic activity is highly elevated. Sympathetic overactivity is a compensatory mechanism at first, but might be detrimental for cardiac function in the long run. We therefore investigated whether chronic low-dose treatment with bisoprolol (a cardioselective β-blocker) has beneficial effects on cardiac function in experimental PH.

METHODS AND RESULTS

PH was induced in rats by a single injection of monocrotaline (60 mg/kg). Pressure telemetry in PH rats revealed that 10 mg/kg bisoprolol was the lowest dose that blunted heart rate response during daily activity. Ten days after monocrotaline injection, echocardiography was performed and PH rats were randomized for bisoprolol treatment (oral gavage) or vehicle (n=7/group). At end of study (body mass loss >5%), echocardiography was repeated, with additional pressure-volume measurements and histomolecular analyses. Compared with control, right ventricular (RV) systolic pressure and arterial elastance (measure of vascular resistance) more than tripled in PH. Bisoprolol delayed time to right heart failure (P<0.05). RV afterload was unaffected, however, bisoprolol treatment increased RV contractility and filling (both P<0.01), and partially restored right ventriculo-arterial coupling and cardiac output (both P<0.05). Bisoprolol restored RV β-adrenergic receptor signaling. Histology revealed significantly less RV fibrosis and myocardial inflammation in bisoprolol treated PH rats.

CONCLUSIONS

In experimental PH, treatment with bisoprolol delays progression toward right heart failure, and partially preserves RV systolic and diastolic function. These promising results suggest a therapeutic role for β-blockers in PH that warrants further clinical investigation.

Body weight loss after myocardial infarction in rats as a marker of early heart failure development

BACKGROUND AND AIMS

We evaluated the use of body weight (BW) loss soon after acute myocardial infarction (MI) in rats as a marker of acute heart failure (HF).

METHODS

Female Wistar rats (200-240 g) were submitted either to sham operation or to coronary artery occlusion. In individual cages, daily BW and food and water intake were measured. Seven days later, cardiac function was evaluated by left ventricular catheterization. HF was defined by a left ventricular end-diastolic pressure greater than the upper limit of the 95% confidence interval. MI group was then divided into those that developed HF (n = 27; MI-HF) and those that did not (n = 47; MI).

RESULTS

The MI-HF group experienced increased BW loss (sham: 4.2 ± 0.6% MI: 0.4 ± 0.8%, MI-HF: -4.9 ± 1.2%; p <0.05) and reduced water and food intake compared with other groups. HF animals showed greater lung weight (sham: 1.460 ± 0.076 g, MI: 1.748 ± 0.086 g, MI-HF: 2.033 ± 0.13 g; p <0.05). Infarct area was significantly different between the groups (MI: 35.9 ± 0.9%, MI-HF: 39.7 ± 1.3%; p <0.05). ROC curve showed that BW loss over 7 days has 100% sensitivity and 72.3% specificity for identifying acute HF. Moreover, excluding the effect of infarct area on these results, a sample of animals with the same infarct area displayed similar morphometric and hemodynamic patterns as the entire sample. Multivariate linear regression analysis confirmed that BW loss is a HF marker independent of infarct area.

CONCLUSIONS

BW is an easy and reliable noninvasive method to detect HF early after MI in rats.

The role of nuclear imaging in the failing heart: myocardial blood flow, sympathetic innervation, and future applications

Heart failure represents a common disease affecting approximately 5 million patients in the United States. Several conditions play an important role in the development and progression of heart failure, including abnormalities in myocardial blood flow and sympathetic innervation. Nuclear imaging represents the only imaging modality with sufficient sensitivity to assess myocardial blood flow and sympathetic innervation of the failing heart. Although nuclear imaging with single-photon emission computed tomography (SPECT) is most commonly used for the evaluation of myocardial perfusion, positron emission tomography (PET) allows absolute quantification of myocardial blood flow beyond the assessment of relative myocardial perfusion. Both techniques can be used for evaluation of diagnosis, treatment options, and prognosis in heart failure patients. Besides myocardial blood flow, cardiac sympathetic innervation represents another important parameter in patients with heart failure. Currently, sympathetic nerve imaging with 123-iodine metaiodobenzylguanidine (123-I MIBG) is often used for the assessment of cardiac innervation. A large number of studies have shown that an abnormal myocardial sympathetic innervation, as assessed with 123-I MIBG imaging, is associated with increased mortality and morbidity rates in patients with heart failure. Also, cardiac 123-I MIBG imaging can be used to risk stratify patients for ventricular arrhythmias or sudden cardiac death. Furthermore, novel nuclear imaging techniques are being developed that may provide more detailed information for the detection of heart failure in an early phase as well as for monitoring the effects of new therapeutic interventions in patients with heart failure.

Heart failure pharmacogenetics: past, present, and future

Heart failure is an increasingly common disease associated with significant morbidity and mortality in the aging population. Recent advances in heart failure pharmacotherapy have established several agents as beneficial to disease progression and outcomes. However, current consensus guideline-recommended pharmacotherapy may not represent an optimal treatment strategy in all heart failure patients. Specifically, individuals with genetic variation in regions central to mediation of beneficial response to standard heart failure agents may not receive optimal benefit from these drugs. Additionally, targeted approaches in phase 3 clinical trials that select patients for inclusion based on the genotype most likely to respond might advance the currently stalled drug development pipeline in heart failure. This article reviews the literature in heart failure pharmacogenetics to date, opportunities for discovery in recent and upcoming clinical trials, as well as future directions in this field.

Natural history of end-stage LV dysfunction: has it improved from the classic Franciosa and Cohn Graph?

The pathophysiology of heart failure is complex, and downstream effects cause decline in multiple systems. Medical therapies intended to slow or reverse disease progression have been shown to improve prognosis in prospective trials. Improvement in prognosis has also been observed in large cohorts across time strata. However, near-term mortality for those with advanced disease remains unacceptably high. Prognosis in advanced heart failure may be assessed with the appropriate use of clinical prediction tools. Optimal timing of evaluation for heart transplantation and/or mechanical circulatory support depends on an understanding of these issues.

Subjective social status predicts in vivo responsiveness of β-adrenergic receptors

OBJECTIVE

Several poor health outcomes, including cardiovascular risk, have been associated with both subjective social status (SSS) and sympathetic overactivity. Because prolonged sympathetic overactivation down regulates beta adrenergic receptor (β-AR) function, reduced β-AR responsiveness is considered an indicator of sympathetic overactivity and a cardiovascular risk factor. Though prior research has focused on objective social status and β-AR function, no studies have examined the association between SSS and β-AR function. We aimed to learn whether SSS predicts the in vivo responsiveness of β-ARs.

METHODS

We assessed the chronotropic 25 dose (CD25), an in vivo marker of β-AR responsiveness, in 94 healthy participants. The MacArthur scales of subjective social status were used to assess SSS in the U.S.A. (SSS-USA) and in the local community (SSS-C). Objective social status was analyzed by calculating the Hollingshead two-factor index.

RESULTS

β-AR responsiveness was reduced (as indicated by higher CD25 values) in participants with lower SSS-USA (p = .007) and lower SSS-C (p < .001). The relationship between CD25 and SSS was particularly robust with respect to SSS-C. Hierarchical regression analyses revealed that SSS-C remained a significant predictor of CD25 (p < .001) and accounted for 14% of the total variance (32%) in CD25 after adjusting for sociodemographic variables (age, ethnicity, gender), health factors (exercise, smoking status, body mass index) and objective social status.

CONCLUSION

Our results indicate that β-AR function may be an important component of the link between SSS and health.

Impact of dopamine infusion on renal function in hospitalized heart failure patients: results of the Dopamine in Acute Decompensated Heart Failure (DAD-HF) Trial

BACKGROUND

Worsening renal function (WRF) and hypokalemia related to diuretic use for acute decompensated heart failure (ADHF) are common and associated with poor prognosis. Low-dose dopamine infusion improves renal perfusion; its effect on diuresis or renal function specifically in ADHF is not known.

METHODS AND RESULTS

Sixty consecutive ADHF patients (age 75.7 ± 11.2 years; 51.7% female; left ventricular ejection fraction 35.3 ± 12.1%) were randomized, after receiving a 40 mg intravenous furosemide bolus, to either high-dose furosemide (HDF, 20 mg/h continuous infusion for 8 hours) or low-dose furosemide combined with low-dose dopamine (LDFD, furosemide 5 mg/h plus dopamine 5 μg kg(-1) min(-1) continuous infusion for 8 hours). Both strategies were compared for total diuresis, WRF (defined as a rise in serum creatinine of >0.3 mg/dL from baseline to 24 hours), electrolyte balance, and 60-day postdischarge outcomes. Mean hourly excreted urine volume (272 ± 149 mL in HDF vs 278 ± 186 mL in LDFD group; P = .965) and changes in dyspnea score (Borg index: -4.4 ± 2.1 in HDF group vs -4.7 ± 2.0 in LDFD group; P = .575) during the 8 hours of protocol treatment were similar in the two groups. WRF was more frequent in the HDF (n = 9; 30%) than in the LDFD group (n = 2; 6.7%; P = .042). Serum potassium changed from 4.3 ± 0.5 to 3.9 ± 0.4 mEq/L at 24 hours (P = .003) in the HDF group and from 4.4 ± 0.5 to 4.2 ± 0.5 mEq/L at 24 hours (P = .07) in the LDFD group. Length of stay and 60-day mortality or rehospitalization rates (all-cause, cardiovascular, and worsening HF) were similar in the two groups.

CONCLUSIONS

In ADHF patients, the combination of low-dose furosemide and low-dose dopamine is equally effective as high-dose furosemide but associated with improved renal function profile and potassium homeostasis.

Interaction between loop diuretic-associated mortality and blood urea nitrogen concentration in chronic heart failure

OBJECTIVES

The purpose of this study was to investigate whether a surrogate for renal neurohormonal activation, blood urea nitrogen (BUN), could identify patients destined to experience adverse outcomes associated with the use of high-dose loop diuretics (HDLD).

BACKGROUND

Loop diuretics are commonly used to control congestive symptoms in heart failure; however, these agents cause neurohormonal activation and have been associated with worsened survival.

METHODS

Subjects in the BEST (Beta-Blocker Evaluation of Survival Trial) receiving loop diuretics at baseline were analyzed (N = 2,456). The primary outcome was the interaction between BUN- and HDLD-associated mortality.

RESULTS

In the overall cohort, HDLD use (≥160 mg/day) was associated with increased mortality (hazard ratio [HR]: 1.56; 95% confidence interval [CI]: 1.35 to 1.80). However, after extensively controlling for baseline characteristics, this association did not persist (HR: 1.06; 95% CI: 0.89 to 1.25). In subjects with BUN levels above the median (21.0 mg/dl), both the unadjusted (HR: 1.59; 95% CI: 1.34 to 1.88) and adjusted (HR: 1.29; 95% CI: 1.07 to 1.60) risk of death was higher in the HDLD group. In patients with BUN levels below the median, there was no associated risk with HDLD (HR: 0.99; 95% CI: 0.75 to 1.34) and after controlling for baseline characteristics, the HDLD group had significantly improved survival (HR: 0.71; 95% CI: 0.49 to 0.96) (p interaction = 0.018).

CONCLUSIONS

The risk associated with HDLD use is strongly dependent on BUN concentrations with reduced survival in patients with an elevated BUN level and improved survival in patients with a normal BUN level. These data suggest a role for neurohormonal activation in loop diuretic-associated mortality.

LOX-1 abrogation reduces cardiac hypertrophy and collagen accumulation following chronic ischemia in the mouse

We hypothesized that lectin-like oxidized LDL receptor-1 (LOX-1) deletion may inhibit oxidative stress signals, reduce collagen accumulation and attenuate cardiac remodeling after chronic ischemia. Activation of LOX-1 plays a significant role in the development of inflammation, apoptosis and collagen signals during acute ischemia. Wild-type and LOX-1 knockout (KO) mice were subjected to occlusion of left coronary artery for 3 weeks. Markers of cardiac hypertrophy, fibrosis-related signals (collagen IV, collagen-1 and fibronectin) and oxidant load (nicotinamide adenine dinucleotide phosphate oxidase expression, activity of mitogen-activated protein kinases and left ventricular (LV) tissue thiobarbituric acid reactive substances) were analyzed. In in vitro experiments, HL-1 cardiomyocytes were transfected with angiotensin II (Ang II) type 1 receptor (AT1R) or type 2 receptor (AT2R) genes to determine their role in the cardiomyocyte hypertrophy. LOX-1 KO mice had 25% improvement in survival over the 3-week period of chronic ischemia. LOX-1 deletion reduced collagen deposition and cardiomyocyte hypertrophy (∼75%) in association with a decrease in oxidant load and AT1R upregulation (all P<0.05). The LOX-1 KO mice hearts exhibited a disintegrin and metalloproteinase 10 (ADAM10) and a disintegrin and metalloproteinase 17 (ADAM17) expression and matrix metalloproteinase 2 activity, and increased AT2R expression (P<0.05). Attenuation of cardiac remodeling was associated with improved cardiac hemodynamics (LV ±dp/dt and cardiac ejection fraction). In vitro studies showed that it is AT1R, and not AT2R overexpression that induces cardiomyocyte hypertrophy. We demonstrate for the first time that LOX-1 deletion reduces oxidative stress and related intracellular signaling, which leads to attenuation of the positive feedback loop involving AT1R and LOX-1. This results in reduced chronic cardiac remodeling.

Statins do not significantly affect muscle sympathetic nerve activity in humans with nonischemic heart failure: a double-blind placebo-controlled trial

BACKGROUND

Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) have been shown to reduce sympathetic nervous system (SNS) activation in experimental heart failure (HF). However, this potential mechanism of action of statins in HF has not been well studied in humans.

METHODS AND RESULTS

Twenty-six patients with nonischemic systolic HF (left ventricular ejection fraction [LVEF] ≤35%) were randomized to atorvastatin (10 mg) or placebo for 3 months. Pre- and posttreatment testing included echocardiography, laboratory assays, quality of life (QOL) questionnaires, and peroneal nerve muscle sympathetic nerve activity (MSNA) via microneurography. Eighteen subjects had technically adequate MSNA tracings before and after treatment. The cohort was 65% male, 81% New York Heart Association functional class II, LVEF 26 ± 6%, and low-density lipoprotein cholesterol (LDL-C) 108 ± 26 mg/dL. Baseline MSNA was 41 ± 2 bursts/min. LDL-C significantly decreased in the atorvastatin (-36.8%) versus the placebo (-0.1%) group (P < .0001). However, there was no significant change in MSNA (-16.2% vs -2.5%), LVEF, B-type natriuretic peptide, or QOL score in the atorvastatin compared with the placebo group.

CONCLUSIONS

Short-term statin therapy in patients with nonischemic HF does not result in a significant decrease in SNS activation as measured by MSNA. These findings are consistent with the neutral outcomes of large clinical trials of statins in HF.

PET and PET/CT in cardiovascular disease

The present review provides an overview of the role of cardiac positron emission tomography in the diagnosis and management of cardiovascular disease. It expands on the relative advantages and disadvantages over other imaging modalities as well as the available evidence supporting its value in the diagnosis and management of patients with coronary artery disease, the assessment of myocardial viability, and evaluation of the cardiac sympathetic nervous system. Furthermore, the recent developments, such as the implementation of high-end computed tomography devices to form hybrid systems, and the advances of molecular imaging probes in experimental applications are briefly discussed.

Use of oral proton pump inhibitors is not associated with harm in patients with chronic heart failure in an ambulatory setting

AIMS

Proton pump inhibitors (PPIs) produce negative inotropic effects on the human myocardium at clinically relevant plasma concentrations. We conducted this study to determine whether PPI use was associated with excess mortality in patients with both ischaemic and non-ischaemic heart failure (HF).

METHODS AND RESULTS

The impact of PPIs on all-cause mortality was examined using a population-based cohort of Alberta residents over the age of 65 with a diagnosis of HF, logistic regression analysis, and a nested case-control study were used to examine the association between current medication use and mortality. Compared with non-PPI users (n= 15,676, 71% of the HF cohort), PPI users (n= 6431, 29% of the HF cohort) were more likely to be women and had more co-morbidities. Mortality in the first year after diagnosis of HF was 32% (n= 5659) in PPI non-users and 26% (n= 1153) in PPI users. Logistic regression modelling showed that PPI use was associated with a relative reduction in mortality rates compared with non-use [adjusted odds ratio (aOR) = 0.87, 95% confidence interval (CI) 0.81-0.93]. Nested case-control analysis of the 5815 patients who died matched to 9934 controls, revealed that current PPI use was not associated with excess mortality (aOR 0.88, 95%CI 0.77-1.01), while use of angiotensin-converting enzyme inhibitors/angiotensin receptor blocker s (aOR 0.70, 95%CI 0.62-0.79) or beta-blockers (aOR 0.57, 95%CI 0.50-0.66), was associated with a relative reduction in mortality.

CONCLUSION

The use of PPIs in patients with HF is common. Despite in vitro concerns about negative inotropic effects with PPIs, there is no association with increased risk of mortality in chronic HF patients who use PPIs in an ambulatory setting.

Renal function in advanced heart failure

Despite recent advances with neurohormonal antagonists and devices, the prognosis of patients with advanced heart failure (HF) remains grave. Renal dysfunction is a common comorbid condition in HF and is associated with adverse outcomes. Current evidence indicates that intrinsic renal disease and inflammation in HF makes the kidney susceptible to hemodynamic compromise and congestion and contributes to a great extent to the development of renal dysfunction. Relief of congestion requires combination treatment with diuretics, neurohormonal antagonists, and occasionally vasodilators as well as inotropes. However, high doses of diuretics may accelerate the development of renal dysfunction by increasing neurohumoral activity and inducing renal structural and functional changes. Ultrafiltration should be reserved for patients with true diuretic resistance. Finally, early identification of the "patient at risk" remains a challenging issue and is limited by the currently used conventional parameters of renal function. However, novel biomarkers of acute kidney ischemia and/or injury are emerging and promise to become a diagnostic option for this patient population.

Persistent sympathoexcitation long after submaximal exercise in subjects with and without coronary artery disease

There is an increased risk of cardiac events after exercise, which may, in part, be mediated by the sympathoexcitation that accompanies exercise. The duration and extent of this sympathoexcitation following moderate exercise is unknown, particularly in those with coronary artery disease (CAD). Twenty control subjects (mean age, 51 years) and 89 subjects with CAD (mean age, 58 years) underwent two 16-min bicycle exercise sessions followed by 30-45 min of recovery. Session 1 was performed under physiological conditions to peak workloads of 50-100 W. In session 2, parasympathetic blockade with atropine (0.04 mg/kg) was achieved at end exercise at the same workload as session 1. RR interval was continually recorded, and plasma catecholamines were measured at rest and selected times during exercise and recovery. Parasympathetic effect, measured as the difference in RR interval with and without atropine, did not differ between controls and CAD subjects in recovery. At 30 and 45 min of recovery, RR intervals were 12% and 9%, respectively, shorter than at rest. At 30 and 45 min of recovery, plasma norepinephrine levels were 15% and 12%, respectively, higher than at rest. A brief period of moderate exercise is associated with a prolonged period of sympathoexcitation extending >45 min into recovery and is quantitatively similar among control subjects and subjects with CAD, with or without left ventricular dysfunction. Parasympathetic reactivation occurs early after exercise and is also surprisingly quantitatively similar in controls and subjects with CAD. The role of these autonomic changes in precipitating cardiac events requires further evaluation.

Modulation of beta-adrenergic receptor signaling in heart failure and longevity: targeting adenylyl cyclase type 5

Despite remarkable advances in therapy, heart failure remains a leading cause of morbidity and mortality. Although enhanced beta-adrenergic receptor stimulation is part of normal physiologic adaptation to either the increase in physiologic demand or decrease in cardiac function, chronic beta-adrenergic stimulation has been associated with increased mortality and morbidity in both animal models and humans. For example, overexpression of cardiac Gsalpha or beta-adrenergic receptors in transgenic mice results in enhanced cardiac function in young animals, but with prolonged overstimulation of this pathway, cardiomyopathy develops in these mice as they age. Similarly, chronic sympathomimetic amine therapy increases morbidity and mortality in patients with heart failure. Conversely, the use of beta-blockade has proven to be of benefit and is currently part of the standard of care for heart failure. It is conceivable that interrupting distal mechanisms in the beta-adrenergic receptor-G protein-adenylyl cyclase pathway may also provide targets for future therapeutic modalities for heart failure. Interestingly, there are two major isoforms of adenylyl cyclase (AC) in the heart (type 5 and type 6), which may exert opposite effects on the heart, i.e., cardiac overexpression of AC6 appears to be protective, whereas disruption of type 5 AC prolongs longevity and protects against cardiac stress. The goal of this review is to summarize the paradigm shift in the treatment of heart failure over the past 50 years from administering sympathomimetic amine agonists to administering beta-adrenergic receptor antagonists, and to explore the basis for a novel therapy of inhibiting type 5 AC.

Treatment of heart failure with preserved ejection fraction: have we been pursuing the wrong paradigm?

Heart failure with preserved ejection fraction (HF-PEF) is the clinical syndrome of heart failure associated with normal or near-normal systolic function. Because inhibition of the adrenergic and renin-angiotensin-aldosterone systems has been so effective in the treatment of systolic heart failure, these same therapies have been the subject of recent clinical trials of HF-PEF. In this review, we examine the current evidence about treatment of HF-PEF, with particular emphasis on reviewing the literature for large-scale randomized clinical studies. The lack of significant benefit with neurohormonal antagonism in HF-PEF suggests that this condition might not involve neurohormonal activation as a critical pathophysiologic mechanism. Perhaps heart failure as we traditionally think of it is the wrong paradigm to pursue as we try to understand this condition of volume overload known as HF-PEF.

Down-regulation of V1a vasopressin receptors in the cerebellum after myocardial infarction

Vasopressin V1a receptors (V1aR) were found in the cerebellum but their functional role has not been determined. As V1aR are engaged in the central regulation of the cardiovascular system and anxiogenic behavior and their role increases in the heart failure and stress, we decided to find out whether expression of V1aR is altered after myocardial infarction and chronic stressing. RT-PCR and Western blot analysis were performed to determine V1aR mRNA and protein expression in the cerebellum of four groups of rats (control sham-operated, infarcted, chronically stressed and infarcted chronically stressed). The myocardial infarct was produced by left coronary artery ligation, and chronic stressing by exposing the rat for four weeks to different types of mild stressors. The rats were sacrificed four weeks after the myocardial surgery or sham operation. Expressions of V1aR mRNA and protein were significantly lower in the infarcted and infarcted chronically stressed rats than in the sham-operated controls and chronically stressed not infarcted rats. No significant differences were found between the sham-operated controls and chronically stressed rats and between the infarcted rats and infarcted rats exposed to chronic stressing. It is concluded that V1aR mRNA and protein expressions are significantly down-regulated in the rats with the post-infarct heart failure but they are not affected by mild chronic stressing.

Common responses in gene expression by Ephedra herba in brain and heart of mouse

The physiological activities of Ephedra herba have been investigated extensively, particularly in the cardiovascular and cerebrovascular systems. However, the molecular mechanisms underlying the effects of Ephedra herba on the brain and heart have yet to be thoroughly elucidated at the whole genome level. Therefore, the present study focused on the identification of the regulatory pattern of gene expression occurring in response to Ephedra herba, using microarray assays in three mouse organs - namely, the brain, heart and liver. Interestingly, the brain and heart exhibited a similar reciprocal pattern of gene expression during the early stages after the administration of Ephedra herba, whereas the liver evidenced a different gene expression profile. Moreover, pathways analysis showed that genes regulated reciprocally by Ephedra herba were associated with neural disease-related functions, such as the Parkinson's disease pathway, in both the brain and the heart. Promoter sequence analysis demonstrated that reciprocally regulated genes could be classified into subgroups on the basis of the similarity of their transcription factor binding sequences, in which temporally up-regulated genes were clustered as distinctive subgroups. In conclusion, the brain and heart responded commonly to Ephedra herba with a temporally reciprocal pattern of gene expression.

Behavioral cross-sensitization between DOCA-induced sodium appetite and cocaine-induced locomotor behavior

Behavioral sensitization involves increases in the magnitude of a response to a stimulus after repeated exposures to the same response initiator. Administration of psychomotor stimulants and the induction of appetitive motivational states associated with natural reinforcers like sugar and salt are among experimental manipulations producing behavioral sensitization. In rats, repeated administration of the mineralocorticoid agonist deoxycorticosterone acetate (DOCA) initially induces incremental increases in daily hypertonic saline consumption (i.e., sensitization of sodium appetite) in spite of the retention of sodium. The present studies investigated whether sodium appetite sensitization induced by DOCA shares mechanisms similar to those of psychomotor stimulant-induced sensitization, and whether there is evidence for reciprocal cross-sensitization. In Experiments 1 and 3, rats received control or cocaine treatments to induce locomotor sensitization. A week later DOCA (or vehicle) was administered to generate a sodium appetite. Animals pretreated with cocaine showed a greater sodium appetite. In Experiment 2, the order of the putative sensitizing treatments was reversed. Rats first received either a series of DOCA or vehicle treatments either with or without access to saline and were later tested for sensitization of the locomotor response to cocaine. Animals pretreated with DOCA without access to saline showed greater locomotor responses to cocaine than animals receiving vehicle treatments. Together these experiments indicate that treatments generating a sustained salt appetite and producing cocaine-induced psychomotor responses show reciprocal behavioral cross-sensitization. The underlying mechanisms accounting for this relationship may be the fact that psychostimulants and an unresolved craving for sodium can act as potent stressors.