Endothelin in human congestive heart failure

No Additive Effect of Passive Containment Surgery in Patients With Aortic Regurgitation and Left Ventricular Dilation

BACKGROUND

After valve replacement in patients with aortic regurgitation short-term and long-term improvement of left ventricular function are related to early reduction of left ventricular dilatation. This case-control study was conducted to investigate the potential beneficial effects by concomitant application of the Acorn Cor Cap Cardiac Support Device (Acorn Cardiovascular Inc, St. Paul, MN) on reduction of ventricular dilatation in patients with aortic regurgitation and advanced ventricular dilatation undergoing aortic valve replacement.

METHODS

Of ten patients with longstanding aortic regurgitation and ventricular dilatation subjected to aortic valve replacement using mechanical valve prostheses, five were in addition subjected to application of the Cardiac Support Device (Acorn). Cardiac function and dimensions were measured by echocardiography preoperatively and 3 and 12 months postoperatively.

RESULTS

After aortic valve replacement, there was a rapid and sustained decrease in end-diastolic and end-systolic diameters (before operation 72 +/- 4 and 54 +/- 8 mm, to 54 +/- 10 and 40 + 11 mm at 3 months; and 53 +/- 9 and 35 +/- 6 mm, 12 months after operation). This did not differ after Cardiac Support Device (Acorn) application (before operation 74 +/- 1 and 56 +/- 5 mm; 52 +/- 8 and 39 +/- 9 mm, 3 months after operation; and 54 +/- 6 and 39 +/- 8 mm, at 12 months). The left ventricular ejection fraction remained unchanged in both groups.

CONCLUSIONS

Application of the Acorn Cor Cap Cardiac Support Device in patients with aortic regurgitation and severe ventricular dilatation does not influence reverse remodeling or cardiac function compared with aortic valve replacement alone.

Mechanisms of endothelin-1-induced decrease in contractility in adult mouse ventricular myocytes

BACKGROUND AND PURPOSE

The potent vasoconstrictor polypeptide endothelin-1 (ET-1) plays an important pathophysiological role in progression of cardiovascular diseases and elicits prominent effects on myocardial contractility. Although ET-1 produces a positive inotropy in cardiac muscle of most mammalian species, it induces a sustained negative inotropy in mice. This study was performed to gain an insight into the cellular mechanisms underlying the negative inotropy in adult mouse ventricular myocytes.

EXPERIMENTAL APPROACH

Cell shortening and Ca(2+) transients were simultaneously recorded from isolated mouse ventricular myocytes loaded with the Ca(2+)-sensitive fluorescent dye indo-1.

KEY RESULTS

ET-1 decreased cell shortening in a concentration-dependent manner (pD(2) value of 10.1). The ET-1-induced decrease in cell shortening was associated with a decrease in Ca(2+) transients. In addition, the Ca(2+) transient/cell-shortening relationship was shifted to the right by ET-1, indicating decreased myofilament Ca(2+) sensitivity. The instantaneous relationship of the rising phase of the Ca(2+) transient and cell shortening was shifted to the right by ET-1. Decreased Ca(2+) transients and cell shortening induced by ET-1 were markedly attenuated by the specific Na(+)/Ca(2+) exchange inhibitor SEA0400.

CONCLUSIONS AND IMPLICATIONS

ET-1-induced negative inotropy in mouse ventricular myocytes was mediated by decreased Ca(2+) transients and myofilament Ca(2+) sensitivity. These data are entirely consistent with the involvement of increased Ca(2+) extrusion via the Na(+)/Ca(2+) exchanger in the ET-1-mediated decrease in Ca(2+) transients. Decreased Ca(2+) sensitivity may be due to retardation of cell shortening in response to a rise in Ca(2+) transients.

Cardiac GPCRs: GPCR signaling in healthy and failing hearts

G protein-coupled receptors (GPCRs) are widely implicated in human heart disease, making them an important target for cardiac drug therapy. The most commonly studied and clinically targeted cardiac GPCRs include the adrenergic, angiotensin, endothelin, and adenosine receptors. Treatment options focusing on the complex and integrated signaling pathways of these GPCRs are critical for the understanding and amelioration of heart disease. The focus of this review is to highlight the most commonly studied and clinically targeted cardiac GPCRs, placing emphasis on their common signaling components implicated in cardiac disease.

Statins in heart failure. Beyond the lipid lowering effect

Statins, the most widely prescribed medications in patients with hyperlipidemia and coronary heart disease, have a number of pleiotropic actions beyond cholesterol lowering. They improve endothelial function, they have antioxidant and anti-inflammatory effects, they regulate neovascularization and have immunomodulatory activities. Experimental evidence suggests that statins may be beneficial in heart failure as they can inhibit myocardial hypertrophy, reduce cardiomyocyte loss by apoptosis, reduce oxidative stress and restore neurohormonal imbalance. Furthermore small randomised clinical trials showed that short term statin administration may improve key pathophysiological aspects of this syndrome. Finally retrospective analyses of large statin trials imply a long term profit on clinical outcome in this group of patients. These results however need to be reviewed with caution as certain studies have demonstrated that low serum cholesterol is associated with worse prognosis in HF and that ubiquinone levels, a micronutrient with antioxidant actions, reduces significantly following statin administration. Large prospective randomised controlled trials are needed to confirm the beneficial effect of statins on cardiovascular outcome in HF patients and further elucidate the contributing mechanisms. Finally the statin dose and the interaction with co-administered drugs need to be studied.

Big endothelin-1 is not a predictor in aortic stenosis, but is related to arterial blood pressure

BACKGROUND

In aortic stenosis, natriuretic peptides have recently been shown to correlate with ventricular function and to predict symptom-free survival and outcome. Elevated big endothelin-1 (bigET) is associated with poor prognosis in chronic heart failure, but little is known about its role in severe aortic stenosis.

METHODS

In 61 patients with aortic stenosis (71+/-10 years, mean gradient 65+/-20 mm Hg, valve area 0.63+/-0.15 cm2), plasma bigET was determined by radioimmunoassay and related to echocardiographic parameters, symptoms and survival. Patients were followed for 1 year.

RESULTS

BigET (mean 2.3+/-1.5, range 0.1-7.5 fmol/ml) was elevated > or = 1.9 fmol/ml in 54% of patients, but was not correlated to the transvalvular gradients or valve area. BigET did not differ significantly between 14 asymptomatic (2.4+/-1.0 fmol/ml) and 47 symptomatic patients (2.3+/-1.6 fmol/ml), although the highest levels were observed in 5 patients in NYHA class III-IV (4.2+/-2.2 fmol/ml, p=0.035). No significant difference in bigET was observed between 51 survivors and 10 patients who died during follow-up (2.2+/-1.4 vs 2.7+/-1.6 fmol/ml). BigET did not differ between 7 asymptomatic patients developing symptoms and those remaining asymptomatic during follow-up. BigET was significantly related to the systolic blood pressure and left ventricular systolic pressure (r=0.389, p=0.0025 and r=0.401, p=0.0018, respectively), but not to the diastolic blood pressure or interventricular septal wall thickness. BigET was inversely related to the left ventricular ejection fraction (r=0.327, p=0.01) and fractional shortening (r=0.391, p=0.044).

CONCLUSION

Although frequently elevated, bigET-1 is not a useful predictor of symptoms or outcome in patients with severe aortic stenosis. BigET increases inversely with left ventricular function and directly with systolic left ventricular and blood pressure, but is not related to transvalvular gradients or valve area.

Effect of beta-blockade on autonomic modulation of heart rate and neurohormonal profile in decompensated heart failure

BACKGROUND

One of the putative mechanisms for the salutary effects of beta-blockers in patients with congestive heart failure (CHF) is their ability to improve autonomic dysfunction. However, patients with profound neurohumoral abnormalities derive little survival benefit from beta-blockers. The purpose of the current study was to evaluate the effect of beta-blockers on heart rate variability (HRV) in decompensated CHF.

METHODS

Time and frequency domain HRV indices were obtained from 24-hour Holter recordings and compared to assess the role of beta-blockade in 199 patients (mean age 60 +/- 14 years) with decompensated CHF. Neurohormonal differences were assessed by measuring norepinephrine, endothelin-1, tumor necrosis factor-alpha, and interleukin-6 in a subset of 64 patients.

RESULTS

All HRV indices were markedly suppressed but were substantially higher in patients who were on beta-blockers. Time domain measures of parasympathetic cardiac activity, the percentage of R-R intervals with > 50 ms variation (4.9 +/- 0.6 vs 7.7 +/- 1.2%, P = 0.006) and the square root of mean squared differences of successive R-R intervals (22.7 +/- 2.0 vs 31.6 +/- 4.1 ms, P = 0.004), were higher in the beta-blocker group. Spectral analysis revealed that the total power and the ultra-low frequency power were significantly higher in patients on beta-blockers (82% and 59%, respectively). The high frequency power, a spectral index of parasympathetic modulation, was 41% higher in the beta-blocker group (121 +/- 25 vs 171 +/- 27 ms(2), P = 0.02). Norepinephrine and interleukin-6 levels were substantially lower in patients on beta-blockers (28% and 61%, respectively). However, these differences did not reach statistical significance.

CONCLUSIONS

Beta-blockers improve the impaired cardiac autonomic regulation during high sympathetic stress of decompensated CHF. This effect may play an important role in protecting the myocardium and preventing arrhythmias during transient increases in sympathetic activity.

The prognostic value of big endothelin-1 in more than 2,300 patients with heart failure enrolled in the Valsartan Heart Failure Trial (Val-HeFT)

BACKGROUND

Endothelin is elevated in heart failure and contributes to neurohormonal activation, hemodynamic deterioration, and cardiovascular remodeling. Here, we examined its prognostic value in a large population of patients with chronic heart failure.

METHODS AND RESULTS

Big endothelin-1 (Big ET-1) and 4 other neurohormones were measured at study entry in 2359 patients enrolled in the Valsartan Heart Failure Trial (Val-HeFT) and their concentrations related to outcome over a median follow-up of 23 months. Baseline concentration of Big ET-1 (median 0.80 pmol/L) was proportional to severity of disease (New York Heart Association class, left ventricular structure and function). High circulating concentrations of brain natriuretic peptide (BNP), creatinine and bilirubin, advanced New York Heart Association class, elevated body mass index, and the presence of atrial fibrillation were independently associated to higher concentrations of Big ET-1. Big ET-1 (ranking second just behind BNP among neurohormonal factors) was an independent predictor of outcome defined as all-cause mortality (hazard ratio 1.49, 95% CI 1.20-1.84, P = .0003) or the combined endpoint of mortality and morbidity (hazard ratio 1.43, 95% CI 1.20-1.69, P < .0001) and provided incremental prognostic value compared with BNP.

CONCLUSIONS

In a large population of patients with symptomatic heart failure, the circulating concentration of Big ET-1, a precursor of the paracrine and bioactive peptide ET-1, was an independent marker of mortality and morbidity. In this setting, BNP remained the strongest neurohormonal prognostic factor.

Erectile Dysfunction in Heart Failure Patients

Chronic heart failure (HF) and erectile dysfunction (ED) are 2 highly prevalent disorders that frequently occur concomitantly. Coronary artery disease, HF, and ED share several common risk factors, including diabetes mellitus, hypertension, smoking, and dyslipidemia. Additionally, the distinct physiologic sequelae of HF create unique organic and psychologic factors contributing to ED in this patient population. Standard HF therapy with beta-receptor blockers, digoxin and thiazide diuretics may worsen sexual dysfunction owing to medication side effects. This may, in turn, lead to noncompliance in misguided efforts to retain satisfactory sexual activity, with secondary worsening of cardiac capacity. This review describes the unique aspects of ED in the HF population.

Elevated salivary endothelin levels in oral cancer patients--a pilot study

The analysis of saliva has been proposed as a potentially rapid, non-invasive method to monitor and diagnose patients with oral disease. In this study we measured salivary endothelin-1 (ET-1) levels in patients diagnosed with oral squamous cell carcinoma (SCC) prior to treatment. We demonstrate significantly elevated salivary ET-1 levels in the oral SCC group (4.37+/-1.35pg/ml), relative to the control group (1.16+/-0.29pg/ml). ET-1 and ET-1 mRNA were also measured in oral SCC tissue specimens and compared to normal oral epithelial controls. The concentration of ET-1 in the oral SCC specimens was 17.87+/-4.0pg/ml and in the normal epithelial controls the concentration of ET-1 was 5.43+/-2.5pg/ml. ET-1 mRNA was significantly overexpressed in 80% (8/10) of the oral SCC specimens. Our results demonstrate the potential utility of salivary analysis for ET-1 levels to monitor patients at risk for oral SCC.

Endothelin receptor antagonists

Endothelin receptor antagonists (ERAs) have been developed to block the effects of endothelin-1 (ET-1) in a variety of cardiovascular conditions. ET-1 is a powerful vasoconstrictor with mitogenic or co-mitogenic properties, which acts through the stimulation of 2 subtypes of receptors [endothelin receptor subtype A (ETA) and endothelin receptor subtype B (ETB) receptors]. Endogenous ET-1 is involved in a variety of conditions including systemic and pulmonary hypertension (PH), congestive heart failure (CHF), vascular remodeling (restenosis, atherosclerosis), renal failure, cancer, and cerebrovascular disease. The first dual ETA/ETB receptor blocker, bosentan, has already been approved by the Food and Drug Administration for the treatment of pulmonary arterial hypertension (PAH). Trials of endothelin receptor antagonists in heart failure have been completed with mixed results so far. Studies are ongoing on the effects of selective ETA antagonists or dual ETA/ETB antagonists in lung fibrosis, cancer, and subarachnoid hemorrhage. While non-peptidic ET-1 receptor antagonists suitable for oral intake with excellent bioavailability have become available, proven efficacy is limited to pulmonary hypertension, but it is possible that these agents might find a place in the treatment of several cardiovascular and non-cardiovascular diseases in the coming future.

Cloning of cDNA encoding canine endothelin receptors and their expressions in normal tissues

The receptors for endothelin (ET) family, ETA and ETB, were molecularly cloned and the expression of ETA and ETB as well as preproendothelin-1 (PPET-1, precursor of ET-1) was examined in normal canine tissues by RT-PCR. The entire open reading frames of the canine ETA and ETB were shown to encode 427 and 442 amino acid residues, respectively, showing from 87.4 to 97.3% sequence similarity to human, mouse, and rat counterparts. ETA and ETB mRNAs were ubiquitously expressed in a variety of canine tissues in this study and PPET-1 mRNA was detected in the tissues except for heart and liver. It was speculated that ET could play an important role in physiological events in most of the organs.

Aldosterone breakthrough during ras blockade: A role for endothelins and their antagonists?

Activation of the renin-angiotensin system (RAS), with ensuing aldosterone excess, detrimentally affects outcome in patients with hypertension and heart failure (HF). RAS blockade with angiotensin (Ang) 1-converting enzyme inhibitors (ACEIs) or Ang II type 1 receptor blockers (ARBs) is beneficial in such conditions. However, aldosterone secretion can persist despite these treatments. Hence, mechanisms besides Ang II acquire the role of aldosterone secretagogue. The RALES and EPHESUS studies have shown that this aldosterone "escape" or "breakthrough" is an important factor, because it is a determinant of outcome in HF patients. Endothelin (ET)-1, which stimulates aldosterone secretion via both A (ETA) and B (ETB) receptor subtypes, and which is increased in HF, is a candidate for the "aldosterone breakthrough." Moreover, the novel ET peptide ET-1(1-31) is involved in adrenocortical growth. Therefore, findings suggesting a role for the ET-1 system as an aldosterone secretagogue, along with the potential usefulness of endothelin antagonists for the prevention of "aldosterone breakthrough," are discussed.

Serum biomarkers for heart failure

The incidence of heart failure has been steadily increasing over the past several decades. High readmission rates in patients with acute decompensated heart failure led to the search for biomarkers that could predict future clinical course and would, in an ideal case, enable monitoring of patients with heart failure and guidance of their therapy. From among several promising markers, the B-type natriuretic peptide and the biologically inactive N-terminal portion of its pro-hormone, NT-proBNP, have become the most frequently used analytes. Other known markers, such as atrial natriuretic peptide and endothelin-1, are currently used for research purposes. The development of additional biomarkers will be an important step from improving diagnosis and treatment of patients with chronic and acute decompensated heart failure.

beta(2)-Adrenergic stimulation attenuates left ventricular remodeling, decreases apoptosis, and improves calcium homeostasis in a rodent model of ischemic cardiomyopathy

The benefit of the beta(2)-adrenergic agonist, clenbuterol, in left ventricular assist device patients with dilated cardiomyopathy has been reported, but its effect on ischemic heart failure (HF) is unknown. We investigated whether clenbuterol improves left ventricular remodeling, myocardial apoptosis and has synergy with a beta(1) antagonist, metoprolol, in a model of ischemic HF. Rats were randomized to: 1) HF only; 2) HF + clenbuterol; 3) HF + metoprolol; 4) HF + clenbuterol + metoprolol; and 5) rats with sham surgery. HF was induced by left anterior descending artery (LAD) artery ligation and confirmed by decreased left ventricular fractional shortening, decreased maximum left ventricular dP/dt (dP/dt(max)), and elevated left ventricular end-diastolic pressure (LVEDP) compared with sham rats (p < 0.01). After 9 weeks of oral therapy, echocardiographic, hemodynamic, and ex vivo end-diastolic pressure-volume relationship (EDPVR) measurements were obtained. Immunohistochemistry was performed for myocardial apoptosis and DNA damage markers. Levels of calcium-handling proteins were assessed by Western blot analysis. Clenbuterol-treated HF rats had increased weight gain and heart weights versus HF rats (p < 0.05). EDPVR curves revealed a leftward shift in clenbuterol rats versus metoprolol and HF rats (p < 0.05). The metoprolol-treated group had a lower LVEDP and higher dP/dt(max) versus the HF group (p < 0.05). Clenbuterol and metoprolol groups had decreased myocardial apoptosis and DNA damage markers and increased DNA repair markers versus HF rats (all p < 0.01). Protein levels of the ryanodine receptor and sarcoplasmic reticulum calcium-ATPase were improved in clenbuterol-, metoprolol-, and clenbuterol+metoprolol-treated groups versus HF rats. However, as a combination therapy, there were no synergistic effects of clenbuterol+metoprolol treatment. We conclude that clenbuterol ameliorates EDPVR, apoptosis, and calcium homeostasis but does not have synergy with metoprolol in our model of ischemic HF.

Acute and chronic oral magnesium supplementation: effects on endothelial function, exercise capacity, and quality of life in patients with symptomatic heart failure

Endothelial dysfunction is an important pathophysiologic mechanism in the progression of heart failure. The objective of the present study was to determine the effects of acute and chronic oral magnesium supplementation on endothelial function in patients with symptomatic heart failure. Twenty-two symptomatic chronic heart failure patients were randomized to receive 800 mg oral magnesium oxide daily or placebo for 3 months. Data collected included large and small arterial elasticity/compliance, hemodynamic parameters, exercise capacity, and quality-of-life score at baseline, 1 week, and 3 months. Patients who received magnesium had improved small arterial compliance at 3 months from baseline compared with placebo. This study suggests that chronic supplementation with oral magnesium is well tolerated and could improve endothelial function in symptomatic heart failure patients.

Activation of peroxisome proliferator-activated receptor-α and -γ in auricular tissue from heart failure patients

OBJECTIVE

Peroxisome proliferator-activated receptors (PPARs), key transcriptional regulators of lipid and energy metabolism in cardiomyocytes, have recently been proposed to modulate cardiovascular pathophysiological responses in experimental models. However, there is little information about the functional activity of PPARs in human heart failure.

AIMS

To investigate PPAR-alpha and -gamma expression and activity, and the association with ET-1 production and fibrosis, in cardiac biopsies from patients with end-stage heart failure due to ischemic cardiomyopathy (ICM) in comparison and from non-failing donor hearts. All samples were obtained during cardiac transplantation.

METHODS AND RESULTS

Morphological analysis (by Masson trichrome and image analysis) did not detect fibrosis in the left atrium from non-failing donors (NFLA) or from ICM patients (FLA). However, left ventricles from failing hearts (FLV) contained a greater number of fibrotic areas (NFLA: 3.21+/-1.15, FLA: 1.63+/-0.83, FLV: 14.5+/-3.45%; n = 9, P<0.05). By RT-PCR, preproET-1 expression was similar in the non-failing and failing atrium but was significantly higher in the ventricles from failing hearts (NFLA: 1.00+/-0.06, FLA: 1.08+/-0.11, FLV: 1.74+/-0.19; n = 9, P<0.05). PPAR-alpha and PPAP-gamma mRNA (by RT-PCR) and protein (by Western blot) levels were higher in the ventricles from failing hearts compared with the atrium from failing and non-failing hearts. Electrophoretic mobility shift assays showed that PPAR-alpha and PPAP-gamma were not activated in the ventricles (NFLA: 1.00+/-0.11, FLA: 1.89+/-0.24, FLV: 0.95+/-0.07; n = 9, P<0.05).

CONCLUSIONS

These data suggest that PPAR-alpha and PPAP-gamma are selectively activated in the atria from ICM patients and might be functionally important in the maintenance of atrial morphology.

Why do patients with heart failure suffer from erectile dysfunction? A critical review and suggestions on how to approach this problem

Chronic heart failure (HF) is an increasingly common cardiovascular disorder. The goal of health-care providers is to optimize quality of life in this population, including sexual health. Up to 75% of patients with HF report erectile dysfunction (ED). As HF is a condition with distinct physiologic sequelae, some unique organic and psychological factors contributing to ED in this patient population have been identified, along with risk factors common to the development of coronary artery disease, HF and ED. This review describes contributing factors to ED in the setting of HF and highlights treatment considerations for this distinct patient population.

Cardiovascular endothelins: essential regulators of cardiovascular homeostasis

The endothelin (ET) system consists of 3 ET isopeptides, several isoforms of activating peptidases, and 2 G-protein-coupled receptors, ETA and ETB, that are linked to multiple signaling pathways. In the cardiovascular system, the components of the ET family are expressed in several tissues, notably the vascular endothelium, smooth muscle cells, and cardiomyocytes. There is general agreement that ETs play important physiological roles in the regulation of normal cardiovascular function, and excessive generation of ET isopeptides has been linked to major cardiovascular pathologies, including hypertension and heart failure. However, several recent clinical trials with ET receptor antagonists were disappointing. In the present review, the authors take the stance that ETs are mainly and foremost essential regulators of cardiovascular function, hence that antagonizing normal ET actions, even in patients, will potentially do more harm than good. To support this notion, we describe the predominant roles of ETs in blood vessels, which are (indirect) vasodilatation and ET clearance from plasma and interstitial spaces, against the background of the subcellular mechanisms mediating these effects. Furthermore, important roles of ETs in regulating and adapting heart functions to different needs are addressed, including recent progress in understanding the effects of ETs on diastolic function, adaptations to changes in preload, and the interactions between endocardial-derived ET-1 and myocardial pump function. Finally, the potential dangers (and gains) resulting from the suppression of excessive generation or activity of ETs occurring in some cardiovascular pathological states, such as hypertension, myocardial ischemia, and heart failure, are discussed.

Angiotensin II-dependent vascular alterations in young cardiomyopathic hamsters: Role for oxidative stress

Recent studies indicate the presence of vascular alterations in 2-month-old Syrian cardiomyopathic hamsters (SCH). These alterations include enhanced angiotensin-converting enzyme (ACE) activity in the aorta, increased contractile response to angiotensin II and impaired vasorelaxation to acetylcholine in norepinephrine-precontracted aortic rings. The mechanisms leading to these vascular alterations are not known nor has their relationship to the cardiac abnormalities been established. We assessed the status of the cardiovascular system of 2-month-old hamsters first to establish if the observed vascular alterations are secondary to cardiac dysfunction, and second to examine the role of oxidative stress in the etiology of vascular dysfunction. Cardiac function parameters evaluated by echocardiography included stroke volume (SV), left ventricular end-diastolic volume (LVEDV), left ventricular fractional shortening (LVFS), ejection fraction (EF), cardiac output index (COI), heart rate (HR) and left ventricular posterior wall thickness (LVPWT). In addition, heart/body weight (heart/BW) ratios and systolic blood pressure were determined in normal hamsters and SCH. Our results indicated that systolic blood pressure increased 56% in SCH when compared to control animals (P<0.05). The increased blood pressure coexisted with normal COI, SV, LVEDV, LVPWT, LVFS, EF, HR and heart/BW ratios. NAD(P)H oxidase activity increased 77% in SCH compared to control animals (P<0.02). The increased oxidase activity was abolished by pre-treatment of animals with the angiotensin II type 1 receptor blocker losartan (25 mg/kg BW/day) for 10 days. Losartan also abolished the increased blood pressure observed at 2 months of age. The antioxidant N-acetylcysteine (NAC) abrogated the increased blood pressure when administered for 30 days to 1-month-old animals. Altogether, these findings suggest that the angiotensin II-dependent vascular abnormalities present in young cardiomyopathic hamsters are associated with oxidative stress and precede the echocardiographic abnormalities characteristic of heart failure.

Relationship between anemia, cardiac troponin I, and B-type natriuretic peptide levels and mortality in patients with advanced heart failure

BACKGROUND

Anemia has been associated with worse symptoms and increased mortality in patients with advanced HF. The association between anemia and biomarkers of increased HF risk is unknown. This study aimed to evaluate the relationship between hemoglobin (Hb), cardiac troponin I (cTnI), B-type natriuretic peptide (BNP), and mortality in patients with advanced heart failure (HF).

METHODS

A cohort of 264 patients with advanced HF referred to a single university HF center was analyzed. Hb, cTnI, and BNP levels were drawn at time of initial evaluation. Patients were divided into groups based on the presence or absence of anemia, detectable cTnI (> or = 0.04 ng/mL), and elevated BNP (> or = 485 pg/mL).

RESULTS

Mean Hb was 13.0 and the values ranged from 7.7 to 17.9 g/dL. Anemic patients were more likely to have elevated BNP (65.7% vs 47.4%, P = .002). Cardiac troponin I levels were detectable in 50.9% and 46.8% of anemic and non-anemic patients, respectively (P = .3). Anemic patients were at 2.3-fold increased risk of mortality (P = .04). Low Hb, detectable cTnI, and elevated BNP remained independent predictors of mortality on multivariate analysis. Anemia in the setting of detectable cTnI, elevated BNP, or both, was associated with markedly increased mortality.

CONCLUSIONS

Anemia is associated with elevated BNP and increased mortality in HF. Furthermore, elevation of the cardiac biomarkers, BNP and cTnI, in patients with HF and anemia identifies patients at particularly high risk of future events.

Endothelins: Pathophysiology and treatment implications in chronic heart failure

Less than 20 years after its discovery, endothelin is recognized as playing a central role in the pathogenesis of chronic heart failure. Endothelin is not only one of the most potent known vasoconstrictors; it also has multiple other actions. It mediates pathologic hypertrophy and fibrosis of both ventricular and vascular tissues, it potentiates the effects of other neurohormones, and it acts as a proarrhythmic. Endothelin receptor antagonists have been developed to investigate the hypothesis that these adverse effects could be prevented, and experimental studies showed promise in this regard. Clinical studies have confirmed the ability of these new agents to improve hemodynamics, but beneficial effects on clinical outcomes have been more difficult to demonstrate. Further analysis of the data from these trials, as well as other ongoing studies, may provide insight into these disparate findings and guidance for future investigations.

Lower rather than higher levels of B-type natriuretic peptides (NT-pro-BNP and BNP) predict short-term mortality in end-stage heart failure patients treated with nesiritide

Elevated plasma natriuretic peptides in heart failure (HF) usually indicate a poor outcome and low levels a compensated state. In advanced chronic HF, however, low levels may reflect an impaired neurohormonal response. To assess this hypothesis, this study analyzed whether N-terminal-pro-B-type natriuretic peptide (NT-pro-BNP) and B-type natriuretic peptide (BNP) levels were related to mortality in 40 patients treated for decompensated chronic HF. Cardiovascular mortality during follow-up (10 +/- 1 months) was 40%. BNP levels were lower in patients who died (487 +/- 60 vs 836 +/- 99 pg/ml, p <0.02), as were NT-pro-BNP levels (9,507 +/- 1,178 vs 17,611 +/- 4,338 pg/ml, p <0.05). These data support the hypothesis that patients with end-stage HF and poor short-term survival have lower natriuretic peptide levels than those who survive. These findings suggest that the natriuretic peptide system can no longer contribute adequately to neurohormonal compensation and that paradoxically low peptide levels are an adverse prognostic marker in advanced HF.

Increased circulating big endothelin-1, endothelin-1 and atrial natriuretic peptide in infants and children with heart failure secondary to congenital heart disease

In order to characterize the changes of five neurohormones in pediatric patients with varying degrees of congestive heart failure (CHF) secondary to congenital heart disease (CHD), we measured plasma neurohormone levels by using radioimmunoassay or high-performance liquid chromatography in 81 subjects including 13 normal children and 68 pediatric patients with CHD. Patients with CHF (n=27) had elevated levels of big endothelin-1 (big ET-1) (29.5+/-1.6 vs. 18.1+/-2.1 pg/ml, p<0.001), endothelin-1 (ET-1) (17.9+/-1.7 vs. 7.8+/-1.7 pg/ml, p<0.001) and norepinephrine (505.6+/-65.6 vs. 219.6+/-23.3 pg/ml, p<0.01) as compared with healthy control subjects (n=13). Plasma norepinephrine levels (505.6+/-65.6 vs. 230.0+/-8.0 pg/ml, p<0.001) and atrial natriuretic peptide (35.5+/-4.2 vs. 7.6+/-0.6 pg/ml, p<0.001) in the 27 patients with CHF were significantly higher than in the 41 patients without CHF. There was also a highly significant stepwise increase in big ET-1, atrial natriuretic peptide and norepinephrine according to the severity of heart failure. Our results suggest that increased circulating neurohormonal activity in CHD relates to the presence and clinical severity of heart failure in children. Plasma levels of big ET-1 and ET-1 were not only significant markers of CHF but also correlated well with the severity of CHF in CHD with left-to-right shunt.

Direct comparison of selective endothelin A and non-selective endothelin A/B receptor blockade in chronic heart failure

OBJECTIVE

To investigate the potential differential effects of selective endothelin (ET) A and dual ET-A/B receptor blockade in patients with chronic heart failure.

METHODS

Nine patients with chronic heart failure (New York Heart Association class II-III) each received intravenous infusions of BQ-123 alone (selective ET-A blockade) and combined BQ-123 and BQ-788 (dual ET-A/B blockade) in a randomised, placebo controlled, three way crossover study.

RESULTS

Selective ET-A blockade increased cardiac output (maximum mean (SEM) 33 (12)%, p < 0.001) and reduced mean arterial pressure (maximum -13 (4)%, p < 0.001) and systemic vascular resistance (maximum -26 (8)%, p < 0.001), without changing heart rate (p = 0.38). Dual ET-A/B blockade significantly reduced the changes in all these haemodynamic variables compared with selective ET-A blockade (p < 0.05). Selective ET-A blockade reduced pulmonary artery pressure (maximum 25 (7)%, p = 0.01) and pulmonary vascular resistance (maximum 72 (39)%, p < 0.001). However, there was no difference between these effects and those seen with dual ET-A/B blockade. Unlike selective ET-A blockade, dual ET-A/B blockade increased plasma ET-1 concentrations (by 47 (4)% with low dose and 61 (8)% with high dose, both p < 0.05).

CONCLUSIONS

While there appeared to be similar reductions in pulmonary pressures with selective ET-A and dual ET-A/B blockade, selective ET-A blockade caused greater systemic vasodilatation and did not affect ET-1 clearance. In conclusion, there are significant haemodynamic differences between selective ET-A and dual ET-A/B blockade, which may determine responses in individual patients.

Increased circulating endothelins are not of cardiopulmonary origin in heart failure patients

OBJECTIVE

Plasma concentrations of endothelin-1 and big-endothelin are increased in heart failure patients. However, the precise contribution of endothelin secretion from the cardiopulmonary system remains unresolved. The aim of this study was to investigate whether the cardiopulmonary system contributes to the circulating endothelin-1 and big-endothelin concentrations in heart failure patients.

MATERIAL AND METHODS

Blood samples were obtained at right heart catheterization from different cardiovascular regions including the coronary sinus in chronic heart failure patients (n=12) and from age-matched control subjects (n=12).

RESULTS

The peripheral plasma concentrations of endothelin-1 were almost 3-fold higher in heart failure patients compared with the control subjects (1.25 pmol/l, 0.30-8.20 pmol/l (median, range) versus 0.46 pmol/l, 0.10-0.88 pmol/l, p<0.01). However, the endothelin-1 concentration was approximately 25% lower in plasma samples from the coronary sinus than in plasma from the inferior caval vein (p<0.05) in the heart failure patients. There were no differences in big-endothelin concentrations between any of the cardiovascular regions.

CONCLUSIONS

In heart failure patients, increased plasma concentrations of endothelin-1 and big-endothelin mainly reflect an increased secretion from the peripheral endothelium.

Bosentan, the mixed ETA–ETB endothelin receptor antagonist, attenuated oxidative stress after experimental myocardial ischemia and reperfusion

Endothelin-1 has been shown to be associated with greater myocardial ischemia and reperfusion injury in which oxidative stress plays a key role. The efficacy of bosentan, a mixed ETA-ETB endothelin receptor antagonist, in protecting the myocardium from ischemia-reperfusion injury and oxidative stress was studied in open-chest Wistar rats. Anesthetized adult male rats (175-250 g b wt) underwent sham operation (SHAM group) or were subjected to 40 min of myocardial ischemia (MI) induced by temporary occlusion of the left anterior descending coronary artery (LAD) followed by 2 h reperfusion (R). Rats submitted to the MI-R protocol were administered bosentan at a dose of 3 mg/kg i.v. 20 min (BOS group) or saline (CON group) 20 min post-occlusion of LAD. After the 2 h reperfusion period the animals were euthanized and the heart rapidly excised. Cardiac tissue samples were snap frozen in liquid nitrogen for biochemical assay and were fixed in 10% formalin solution for histologic evaluation. Myocardial I-R resulted in a significant increase (p < 0.05) in the myocardial malondialdehyde levels and a decrease (p < 0.01) in the myocardial reduced glutathione content. These changes were associated with significant decreases in the myocardial activity of antioxidant enzymes superoxide dismutase (p < 0.05) and catalase (p < 0.01) and severe tissue damage in the jeopardized myocardium in the CON group as compared with the non-myocardial ischemia-reperfusion (NMI-R) SHAM group. Bosentan exerted marked tissue protective effect as assessed by histologic evaluation of the myocardium. The drug significantly (p < 0.05) attenuated myocardial oxidative stress and restored the cellular antioxidant defense mechanisms as compared with the saline-treated controls subjected to the MI-R protocol. Furthermore, bosentan also exerted a marked effect on peripheral hemodynamics and heart rate during the reperfusion phase (data reported elsewhere). These results are consistent with the concept that endothelin-1 may be involved in the pathogenesis of myocardial ischemia and infarction. This study demonstrates the antioxidant effect of non-selective endothelin receptor antagonism elucidating that, part of the aetiology of ischemia and reperfusion induced myocardial injury involves impaired antioxidant defenses.

Differential action of a protein tyrosine kinase inhibitor, genistein, on the positive inotropic effect of endothelin-1 and norepinephrine in canine ventricular myocardium

Experiments were carried out in isolated canine ventricular trabeculae and acetoxymethylester of indo-1-loaded single myocytes to elucidate the role of protein tyrosine kinase (PTK) in the inotropic effect of endothelin-1 (ET-1) induced by crosstalk with norepinephrine (NE). The PTK inhibitor genistein was used as a pharmacological tool. Genistein but not daidzein inhibited the positive inotropic effect and the increase in Ca(2+) transients induced by ET-1 by crosstalk with NE at low concentrations. Genistein and daidzein antagonized the negative inotropic effect and the decrease in Ca(2+) transients induced by ET-1 by crosstalk with NE at high concentrations, but genistein did not affect the antiadrenergic effect of carbachol. Genistein but not daidzein enhanced the positive inotropic effect and the increase in Ca(2+) transients induced by NE via beta-adrenoceptors, while the enhancing effect of genistein was abolished by the protein tyrosine phosphatase inhibitor vanadate. These findings indicate that genistein (1) induces a positive inotropic effect in association with an increase in Ca(2+) transients, (2) inhibits the positive inotropic effect of ET-1 induced by crosstalk with NE, and (3) enhances the positive inotropic effect of NE induced via beta-adrenoceptors by inhibition of PTK. In addition, genistein inhibits the negative inotropic effect of ET-1 induced by crosstalk with NE through a PTK-unrelated mechanism. PTK may play a crucial role in the receptor-mediated regulation of cardiac contractile function in canine ventricular myocardium.

Urotensin II in patients with chronic heart failure

BACKGROUND

Human Urotensin II (hU-II) is the most potent vasoconstrictor known to date. HU-II receptors are predominant in the human heart and arterial vessels, suggesting hU-II to be of importance as a cardiovascular mediator.

METHODS

We studied 32 consecutive patients (60+/-12 years) with chronic heart failure (CHF) and 10 control subjects (54+/-12 years, n.s.) with cardiopulmonary exercise testing. Blood samples for the measurement of plasma hU-II and big-endothelin-1 (big-ET1) were obtained at rest and at peak exercise.

RESULTS

Peak VO(2) was significantly higher in controls than in CHF patients (19.8+/-3.8 vs. 14.7+/-3.6 ml min(-1) kg(-1), P<0.001). Big-ET1 levels were increased in CHF compared to controls at rest (2.8+/-1.8 vs. 1.7+/-0.1 fmol/ml, P<0.01) and at peak exercise (2.7+/-1.7 vs. 1.6+/-0.2 fmol/ml, P<0.005). HU-II concentrations were comparable in patients with CHF and controls at rest (2990+/-1104 vs. 3290+/-508 pg/ml, n.s.) and peak exercise (3063+/-1185 vs. 3213+/-1188 pg/ml, n.s.). Resting hU-II levels demonstrated no correlation with peak VO(2) in controls or CHF patients.

CONCLUSIONS

The measurement of circulating plasma levels of hU-II does not seem to be very helpful in studying the effects of hU-II in human cardiovascular regulation. A local paracrine or autocrine mediator effect of hU-II in CHF is possible.

Inflammation and endothelial dysfunction as therapeutic targets in patients with heart failure

Evidence suggests that vascular endothelium plays key role in the regulation of vascular tone, in the process of inflammation and in the thrombotic mechanisms. Recent studies indicate that it is an important component of the pathophysiological mechanisms of heart failure. Heart failure may induce endothelial dysfunction by different mechanisms, such as reduced synthesis and release of nitric oxide (NO), increased degradation of NO or by increased production of endothelin-1. In addition, endothelial dysfunction has been associated with the progression of heart failure. Alterations in neurotransmitters, hormones and also in physiological stimuli are present in heart failure and affect the vascular endothelium. Treatments with beneficial effects on endothelial dysfunction may also improve prognosis in patients with heart failure.

Superiority of big endothelin-1 and endothelin-1 over natriuretic peptides in predicting survival in severe congestive heart failure: a 7-year follow-up study

BACKGROUND

Plasma concentrations of atrial and brain natriuretic peptides (ANP, BNP), of their N-terminal pro-peptides, of endothelin-1 (ET-1), and big endothelin-1 (big ET-1) have diagnostic and prognostic significance in congestive heart failure (CHF). However, their respective values as a predictor of survival remain controversial and have never been directly compared in severe CHF.

METHODS AND RESULTS

We analyzed, in 47 patients with severe CHF (New York Heart Association [NYHA] class III to IV; age 66 +/- 8 years, ejection fraction 20 +/- 6%), the prognostic performance of a panel of neurohormones and assays (N-terminal pro-ANP 1-25, 68-98 by radioimmunoassay [RIA], and 1-98 by enzyme-linked immunosorbent assay [ELISA], BNP by RIA and immunoradiometric assay [IRMA], N-terminal pro-BNP by Elisa, ET-1 by RIA, and big ET-1 by RIA and Elisa. Data were compared with 40 patients with mild to moderate CHF [NYHA I-II] and 30 healthy subjects. After a follow-up of 81 +/- 15 months, there were 34 deaths and 1 heart transplant. All neurohormones were significantly higher at baseline in patients with severe than in mild to moderate CHF or healthy subjects (all P < .001). Although all neurohormones but BNP IRMA were significant predictors of survival in univariate analysis, only big ET-1 RIA and ET-1 were independent predictors of survival (improvement chi(2): 7.5 and 4.6, P < .01 and P < .05). Using medians as cutpoints of big ET-1 RIA and ET-1, 2 severe CHF populations were defined with a different outcome (5-year survival: 55 versus 18%, P < .01).

CONCLUSIONS

Big ET-1 and ET-1 are strong independent predictors of survival in patients with severe CHF and better for this purpose than natriuretic peptides or their pro-peptides. These markers allow easily to identify a population with a very high risk mortality eligible for more aggressive therapies.

Bigendothelin-1 via p38-MAPK-dependent mechanism regulates adult rat ventricular myocyte contractility in sepsis

We tested the hypothesis that exogenous administration of the ET-1 precursor, bigET-1, would regulate adult rat ventricular myocyte (ARVM) contractility in a p38-mitogen activated protein kinase (p38-MAPK)-dependent mechanism during sepsis. Ventricular myocytes from adult rat hearts (both sham and septic) were stimulated to contract at 0.5 Hz and mechanical properties were evaluated using an IonOptix Myocam system. Immunoblot analysis was used to determine the phosphorylation of p38-MAPK and extracellular signal-regulated kinase 1/2 (ERK1/2). ARVMs were treated with vehicle, bigET-1 and inhibitors for 24 h and then subjected to functional and biochemical estimations. Septic ARVM displayed a distorted cell membrane and irregular network within the cells along with increased cell contractility as evidenced by elevated peak shortening (PS), maximal velocity of shortening (+dL/dt) and relengthening (-dL/dt) in comparison to sham ARVM. BigET-1 treatment caused ARVM enlargement in both sham and sepsis groups. BigET-1 (100 nM) produced an increase in ARVM contractility in sham group as compared to vehicle treatment. However, septic ARVM treated with bigET-1 exhibited unaltered ARVM contractility, and upregulated ET(B) receptors as compared to respective sham group. BigET-1 increased the concentration of ET-1 and upregulated phosphorylation of p38-MAPK but not of ERK1/2 in sham and septic ARVM. Furthermore, inhibition of p38-MAPK by SB203580 (10 microM) increased ARVM contractility in sham but not in sepsis group. BigET-1 reversed SB203580-induced increase in PS in sham group but accentuated it in sepsis group. BigET-1 also reversed SB203580-induced inhibition of p38-MAPK phosphorylation in sham but not in septic ARVM. SB203580 pretreatment followed by bigET-1 administration significantly decreased p38-MAPK phosphorylation and downregulated ET(B) receptor expression as compared to bigET-1 treatment per se in sepsis group but not in sham. We concluded that a bigET-1-induced non-responsive effect on septic ARVM contractile function could be due to upregulation of p38-MAPK phosphorylation and ET(B) receptor expression.

Receptor subtypes mediating the inotropic effects and Ca(2+) signaling induced by endothelin-1 through crosstalk with norepinephrine in canine ventricular myocardium

In canine ventricular myocardium, endothelin-1 (ET-1) alone induced only a weak transient negative inotropic effect (NIE). However, ET-1 induced a marked sustained positive inotropic effect (PIE) subsequent to a transient NIE in the presence of norepinephrine (NE) at low concentrations (0.1 - 1 nM) and elicited a pronounced sustained NIE in the presence of NE at high concentrations (around 100 nM). Thus, the extent of beta-adrenoceptor stimulation induced by NE played a crucial role in determining the characteristics of the inotropic effects of ET-1. The characteristics of ET receptor subtypes involved in contractile regulation and Ca(2+) signaling induced by ET-1 were determined. The ET-1-induced transient NIE and decrease in Ca(2+) transients were abolished by the selective ET(A)-receptor antagonist FR319317, but not by the selective ET(B)-receptor antagonist BQ-788. The sustained PIE and the increase in Ca(2+) transients induced by ET-1 were abolished by FR319317, but not inhibited by BQ-788. In contrast, the sustained NIE of ET-1 was abolished by the non-selective ET antagonist TAK-044, markedly attenuated by FR319317, and partially inhibited by BQ-788. ET-1 alone elicited a PIE in the presence of BQ-788, which indicates that the activation of ET(B)-receptors counteracts the development of the PIE of ET-1. The current findings indicate that both ET(A) and ET(B) receptors are involved in the regulation of Ca(2+) signaling and contractility in canine ventricular myocardium.

Carvedilol therapy is associated with a sustained decline in brain natriuretic peptide levels in patients with congestive heart failure

BACKGROUND

Beta-blocker therapy improves symptoms, left ventricular ejection fraction (LVEF), and survival in patients with congestive heart failure, but chronic effects on neurohormones have not been extensively investigated. Therefore, we examined the neurohumoral effects of carvedilol.

METHODS

Fifty-five patients with New York Heart Association (NYHA) classes II-III congestive heart failure and LVEF < or =35% entered the study with intention to assess LVEF, NYHA class, plasma brain natriuretic peptide (BNP), N-terminal atrial natriuretic peptide (NANP), big-endothelin, endothelin-1, norepinephrine, and angiotensin II at baseline and at 6 and 12 months after initiation of carvedilol.

RESULTS

Forty-six patients completed 12 months of follow-up. Left ventricular ejection fraction improved from 26% +/- 8% at baseline to 39% +/- 14% at 12 months. New York Heart Association class improved from 2.3 +/- 0.4 at baseline to 1.8 +/- 0.7 at 12 months. Brain natriuretic peptide fell from 453 +/- 784 to 208 +/- 393 pg/mL at 6 months and 223 +/- 334 pg/mL at 12 months ( P = .01 vs baseline). N-terminal atrial natriuretic peptide did not change between baseline and 6 months but fell at 12 months (2117 +/- 1678, 2015 +/- 1532, and 1438 +/- 1442 pg/mL, respectively, P = .001 between baseline and 12 months). Angiotensin II was lower at 6 and 12 months than at baseline (12.6 +/- 10, 7.8 +/- 5.5 pg/mL, P < 0.001, and 11.3 +/- 17.1 pg/mL, P = .02, respectively). Left ventricular ejection fraction at 12 months correlated inversely with BNP level at 12 months (r = -0.55, P = .001).

CONCLUSIONS

Carvedilol therapy is associated with a sustained decline in BNP and NANP levels. Serial BNP levels can provide some guidance regarding probability of LVEF improvement, but the relationship is not strong enough for BNP levels to supplant measurement of LVEF.

The role of endothelin receptor antagonists in cardiovascular pharmacotherapy

Endothelin (ET) is a hormone produced predominantly by endothelial cells which has been recognised to play a significant role in the development of several cardiovascular disease states. In order to combat the deleterious effects of ET, several ET-receptor antagonists (ETRA) are currently in clinical development. The agents developed thus far inhibit the actions of ET through either selective inhibition of the ET(A) receptors or non-selective inhibition of both ET(A) and ET(B) receptors. However, due to the differing proportions of the two receptor subtypes in various tissues, animal models and pathologies, it remains a matter of debate whether receptor selective agents impart significant clinical benefits over non-selective agents. This paper seeks to briefly summarise the important preclinical and clinical effects that have been reported in the literature and will attempt to provide a rationale for the use of both types of ETRAs in the treatment of both systemic and pulmonary hypertension as well as chronic heart failure (CHF).

The therapeutic potential of PD156707 and related butenolide endothelin antagonists

Plasma concentrations of the peptide endothelin (ET) are elevated in several cardiovascular diseases. Animal studies suggest that activation of ET receptors may contribute to the increase in vascular resistance and remodelling of cardiovascular tissues that are characteristic of these pathologies. Antagonists of these receptors may therefore have important clinical potential. PD156707 (Parke-Davis) is one of a series of novel, orally-active butenolide endothelin antagonists and is highly selective for the ETA receptor. In man, this subtype mediates the profound vasoconstrictor effects of the ET peptides, and blockade of the ETA receptor may therefore produce beneficial vasodilatation. The advantage of selective ETA receptor antagonism is that it leaves unaffected vascular ETB receptors, which mediate vasorelaxation, and non-vascular ETB receptors, particularly in the lung and kidneys, which act to clear ET from the plasma. PD156707 exhibits subnanomolar affinity and greater than 1000-fold selectivity for human ETA receptors and potently inhibits ET-1-mediated vasoconstriction in human isolated blood vessels. In rats, PD156707 has good oral bioavailability (41%) and a relatively short terminal t1/2 of approximately 1 h. Structural analogues of PD156707 that have comparable selectivity and potency for the ETA receptor are reported to have even better oral bioavailability and longer plasma t1/2 values. Preclinical studies with PD156707 indicate efficacy in animal models of congestive heart failure (CHF), pulmonary hypertension (PH) and cerebral ischaemia. We await data from clinical trials to confirm the therapeutic potential of the ETA-selective butenolide antagonists in man.

Is the pregnancy hormone relaxin an important player in human heart failure?

BACKGROUND

The pregnancy hormone relaxin has been raised as a new compensatory mediator of cardiac origin in heart failure (HF). We set out to assess the role of relaxin in pressure overload-induced human HF.

METHODS

We studied 129 adult patients undergoing cardiac catheterization for isolated aortic valve stenosis (AS). Blood was sampled from the aortic root and, in a subset of 49 patients, from the coronary sinus for the determination of plasma relaxin by enzyme immunoassay. HF was diagnosed when the patient had dyspnea or fatigue on ordinary effort in association with pulmonary wedge pressure >14 mm Hg at catheterization.

RESULTS

Forty-one patients had HF, which was systolic (ejection fraction <50%) in 16 patients and diastolic in 25 patients. The median plasma relaxin was 32 pg/ml (<12-297 pg/ml) in 88 AS patients without HF, 28 pg/ml (<12-825 pg/ml) in the 41 AS patients with HF, and 42 pg/ml (range, <12-100 pg/ml) in 11 control patients free of heart disease (p=0.82). Plasma relaxin did not correlate with any measurement of cardiac structure or function. The concentration gradients of relaxin from the aortic root to the coronary sinus indicated relaxin extraction by the heart in the control patients (median change, -5 pg/ml, p=0.038) vs. relaxin production in patients with systolic HF (median change, +6 pg/ml, p=0.028) (p=0.002 between groups).

CONCLUSIONS

Although the heart may release relaxin into the circulation in certain forms of HF, this does not translate into elevated systemic concentrations. Relaxin is not a major player in human HF.

Hypertension: a review for clinicians

Despite the existence of a variety of consistent hypertension guidelines,the issue of inadequate management of the condition persists. The challenge for health care professionals is not only to understand and adopt the guidelines but also to take a holistic approach to patient care. In addition, clinicians need to encourage adherence to medication protocols, which will hopefully lead to an overall reduction in morbidity and mortality associated with hypertension. It is the clinician's professional responsibility to be cognizant of the emerging research on vasoactive substances as new drugs are being developed that will effect endothelial receptors. It is important that clinicians are trained appropriately in blood pressure measurement and risk factor identification and intervention.

Intracellular signaling pathways for norepinephrine- and endothelin-1-mediated regulation of myocardial cell apoptosis

Accumulating data support the idea that apoptosis in cardiac myocytes, in part, contributes to the development of heart failure. Since a number of neurohormonal factors are activated in this state, these factors may be involved in the positive and negative regulation of apoptosis in cardiac myocytes. Norepinephrine is one such factor and induces apoptosis in cardiac myocytes via a beta-adrenergic receptor pathway. beta-adrenergic agonist-induced apoptosis in cardiac myocytes is dependent on the activation of the cAMP/protein kinase A pathway. Interestingly, the activation of this pathway protects PC12 cells from apoptosis, suggesting that cAMP/protein kinase A regulates apoptosis in a cell type-specific manner. Another neurohormonal factor activated in heart failure is endothelin-1, which acts as a potent survival factor against myocardial cell apoptosis. Intracellular signaling pathways for endothelin-1-mediated protection include activation of MEK-1 /ERK1/2 and PI3 kinase. In addition to these protective pathways common among cell types, endothelin- activates the calcium-activated phosphatase calcineurin, which is necessary for the nuclear import of NFAT transcription factors. These factors interact with the cardiac-restricted zinc finger protein GATA-4 and induce transcription and expression of anti-apoptotic molecule bcl-2. Thus, myocardial cell apoptosis is regulated by pathways unique to cardiac myocytes as well as by those common among cell types. It should be further determined whether agents that specifically block myocardial cell apoptosis will attenuate the progression of heart failure.