Vascular dysfunction and heart failure: epiphenomenon or etiologic agent?

Oral Cardiac Drug-Gut Microbiota Interaction in Chronic Heart Failure Patients: An Emerging Association

Regardless of the currently proposed best medical treatment for heart failure patients, the morbidity and mortality rates remain high. This is due to several reasons, including the interaction between oral cardiac drug administration and gut microbiota. The relation between drugs (especially antibiotics) and gut microbiota is well established, but it is also known that more than 24% of non-antibiotic drugs affect gut microbiota, altering the microbe's environment and its metabolic products. Heart failure treatment lies mainly in the blockage of neuro-humoral hyper-activation. There is debate as to whether the administration of heart-failure-specific drugs can totally block this hyper-activation, or whether the so-called intestinal dysbiosis that is commonly observed in this group of patients can affect their action. Although there are several reports indicating a strong relation between drug-gut microbiota interplay, little is known about this relation to oral cardiac drugs in chronic heart failure. In this review, we review the contemporary data on a topic that is in its infancy. We aim to produce scientific thoughts and questions and provide reasoning for further clinical investigation.

Accumulated nocturnal hypoxemia predict arterial endothelial function in patients with sleep-disordered breathing with or without chronic heart failure

ABTSRACT

Sleep-disordered breathing (SDB) is often accompanied with the chronic heart failure (CHF). Hypoxemia due to pulmonary congestion from CHF and concurrent SDB might synergistically impair endothelial function and worsen the prognosis. However, the main factors affecting deterioration of endothelial function are unknown and whether the influence of hypoxemia differs in SDB patients with and without CHF remains unclear. Fifty-three patients (CHF group, n = 23; non-CHF group, n = 30) underwent polysomnography to evaluate their SDB and flow-mediated vasodilation (FMD) measurements to assess arterial endothelial function. We examined the relationships between FMD and SDB-related parameters, including our original index of accumulated hypoxemia by SDB throughout one-night sleep: the time desaturation summation index (TDS), calculated as follows: (100% - averaged arterial oxygen saturation during sleep) × total sleep time. The mean age in the CHF and non-CHF groups was 59.0 ± 13.5 and 57.7 ± 11.4 years, respectively. Although the FMD in the 2 groups were not significantly different, well-known adverse factors for FMD such as serum lipid profiles, blood pressure levels, and conventional indices of SDB were worse in the non-CHF group. Only the TDS was not significantly different between 2 groups and associated with FMD as shown by the univariate analysis (CHF: p < 0.05, non-CHF: p < 0.01) and multivariate analysis (CHF: p < 0.05, non-CHF: p < 0.01). Accumulated hypoxemia (TDS) rather than the frequency of hypoxemia might more influence on the endothelial function irrespective of the cardiac state. Removal of accumulation of nocturnal hypoxemia might be a target for treatment equally in the patients with and without CHF.

Exercise training improves vascular reactivity in ovariectomized rats subjected to myocardial infarction

The aim of this study was to evaluate the effects of exercise training (ET) on the aortic vascular reactivity of ovariectomized and infarcted rats. The animals were divided into 5 groups: Control, Ovariectomized + SHAM sedentary (OVX+SHAMSED), OVX+SHAM and ET (OVX+SHAMET), OVX + Myocardial Infarction sedentary (OVX+MISED), and OVX + MI and ET (OVX+MIET). ET protocol (60 minutes/day, 5x/week) in a motorized treadmill began 15 days after MI and lasted 8 weeks. The endothelium-dependent and endothelium-independent vascular reactivity were evaluated as well as the role of the reactive oxygen species (ROS). Superoxide and nitric oxide (NO) production were analyzed in situ using DHE and DAF-2 fluorescence, respectively. The expression of gp91phox and of the antioxidant enzymes were evaluated by western blotting in the thoracic aorta samples. MI promoted a significant increase in the contractile response and impaired endothelium-mediated relaxation. However, ET prevented the impairment in the vascular reactivity in MI animals. In addition, the protein expression of gp91phox and superoxide production increased and the NO production decreased in the OVX+MISED group but not in the OVX+MIET group. Therefore, ET improves vascular reactivity in MI ovariectomized rats by preventing the increase in the expression of gp91phox and the decrease in the antioxidant enzymes, resulting in a normal ROS and NO production. Thus, ET can be an effective therapeutic strategy for improving the MI-induced vascular alterations in estrogen deficiency condition.

Elastase-2, an angiotensin II-generating enzyme, contributes to increased angiotensin II in resistance arteries of mice with myocardial infarction

BACKGROUND AND PURPOSE

Angiotensin II (Ang II), whose generation largely depends on angiotensin-converting enzyme (ACE) activity, mediates most of the renin-angiotensin-system (RAS) effects. Elastase-2 (ELA-2), a chymotrypsin-serine protease elastase family member 2A, alternatively generates Ang II in rat arteries. Myocardial infarction (MI) leads to intense RAS activation, but mechanisms involved in Ang II-generation in resistance arteries are unknown. We hypothesized that ELA-2 contributes to vascular Ang II generation and cardiac damage in mice subjected to MI.

EXPERIMENTAL APPROACH

Concentration-effect curves to Ang I and Ang II were performed in mesenteric resistance arteries from male wild type (WT) and ELA-2 knockout (ELA-2KO) mice subjected to left anterior descending coronary artery ligation (MI).

KEY RESULTS

MI size was similar in WT and ELA-2KO mice. Ejection fraction and fractional shortening after MI similarly decreased in both strains. However, MI decreased stroke volume and cardiac output in WT, but not in ELA-2KO mice. Ang I-induced contractions increased in WT mice subjected to MI (MI-WT) compared with sham-WT mice. No differences were observed in Ang I reactivity between arteries from ELA-2KO and ELA-2KO subjected to MI (MI-ELA-2KO). Ang I contractions increased in arteries from MI-WT versus MI-ELA-2KO mice. Chymostatin attenuated Ang I-induced vascular contractions in WT mice, but did not affect Ang I responses in ELA-2KO arteries.

CONCLUSIONS AND IMPLICATIONS

These results provide the first evidence that ELA-2 contributes to increased Ang II formation in resistance arteries and modulates cardiac function after MI, implicating ELA-2 as a key player in ACE-independent dysregulation of the RAS.

Different Contributions of Physical Activity on Arterial Stiffness between Diabetics and Non-Diabetics

BACKGROUND

We compared the contribution of physical activity to the change in arterial stiffness between patients with and without diabetes in ischemic heart disease.

METHODS

We studied 96 (diabetes) and 109 (without diabetes) patients with ischemic heart disease treated by percutaneous coronary intervention (PCI). Arterial stiffness was assessed by cardio-ankle vascular index (CAVI) at the first diagnosis of significant coronary ischemia and 6 months after PCI and optimal medical therapy. Physical activity was evaluated using the long form of the International Physical Activity Questionnaire (IPAQ).

RESULTS

CAVI values increased more for diabetic patients than for non-diabetic. The IPAQ scores did not differ between the two groups. During follow-up, CAVI values did not significantly change in either group. In diabetic patients, the CAVI score for 48 patients did not change (NC-group) and 48 patients improved (Improved-group). Physical activity scores were 937.9 ± 923.2 and 1524.6 ± 1166.2 in the NC- and Improved-groups, respectively. IPAQ scores and uric acid levels significantly affect CAVI improvement after adjusting for age, sex, baseline CAVI, total cholesterol, and estimated glomerular filtration rate.

CONCLUSION

Determining factors influencing CAVI improvement during follow-up were significantly different between patients with and without diabetes. IPAQ scores and uric acid levels were significantly correlated with CAVI changes.

Cardiovascular Safety in Drug Development

As drug development becomes a long and demanding process, it might also become a barrier to medical progress. Drug safety concerns are responsible for many of the resources consumed in launching a new drug. Despite the money and time expended on it, a significant number of drugs are withdrawn years or decades after being in the market. Cardiovascular toxicity is one of the major reasons for those late withdrawals, meaning that many patients are exposed to unexpected serious cardiovascular risks. It seems that current methods to assess cardiovascular safety are imperfect, so new approaches to avoid the exposure to those undesirable effects are quite necessary. Endothelial dysfunction is the earliest detectable pathophysiological abnormality, which leads to the development of atherosclerosis, and it is also an independent predictor for major cardiovascular events. Endothelial toxicity might be the culprit of the cardiovascular adverse effects observed with a significant number of drugs. In this article, we suggest the regular inclusion of the best validated and less invasive endothelial function tests in the clinical phases of drug development in order to facilitate the development of drugs with safer cardiovascular profiles.

Resveratrol treatment of mice with pressure-overload-induced heart failure improves diastolic function and cardiac energy metabolism

BACKGROUND

Although resveratrol has multiple beneficial cardiovascular effects, whether resveratrol can be used for the treatment and management of heart failure (HF) remains unclear. In the current study, we determined whether resveratrol treatment of mice with established HF could lessen the detrimental phenotype associated with pressure-overload-induced HF and identified physiological and molecular mechanisms contributing to this.

METHODS AND RESULTS

C57Bl/6 mice were subjected to either sham or transverse aortic constriction surgery to induce HF. Three weeks post surgery, a cohort of mice with established HF (% ejection fraction <45) was administered resveratrol (≈320 mg/kg per day). Despite a lack of improvement in ejection fraction, resveratrol treatment significantly increased median survival of mice with HF, lessened cardiac fibrosis, reduced gene expression of several disease markers for hypertrophy and extracellular matrix remodeling that were upregulated in HF, promoted beneficial remodeling, and improved diastolic function. Resveratrol treatment of mice with established HF also restored the levels of mitochondrial oxidative phosphorylation complexes, restored cardiac AMP-activated protein kinase activation, and improved myocardial insulin sensitivity to promote glucose metabolism and significantly improved myocardial energetic status. Finally, noncardiac symptoms of HF, such as peripheral insulin sensitivity, vascular function, and physical activity, were improved with resveratrol treatment.

CONCLUSIONS

Resveratrol treatment of mice with established HF lessens the severity of the HF phenotype by lessening cardiac fibrosis, improving molecular and structural remodeling of the heart, and enhancing diastolic function, vascular function, and energy metabolism.

Risk for cardiovascular events in an Italian population of patients with type 2 diabetes

BACKGROUND AND AIM

This study aims to analyse the risk of cardiovascular events in a local cohort of patients with type 2 diabetes, and to evaluate the prognostic accuracy of four algorithms used to estimate cardiovascular risk: the Framingham study, United Kingdom Prospective Diabetes Study (UKPDS), Riskard study and Progetto Cuore.

METHOD AND RESULTS

We analysed clinical charts of the Diabetes Clinics of Modena for the period 1991-95. Patients in the age range of 35-65 with type 2 diabetes and no previous cardiovascular disease were eligible. The incidence of new cardiovascular disease was compared with estimated rates deriving from the different functions. A stratification was obtained in subgroups at different cardiovascular risk, allowing comparison between the algorithms. A total of 1532 patients were eligible; women presented a worse cardiovascular risk profile. An absolute 10-year rate of cardiovascular events of 14.9% was observed. Comparing patients with events with event-free subjects, we found significant differences in systolic blood pressure, age at visit, smoking, high-density lipoprotein (HDL)-cholesterol, duration of diabetes, glycosylated haemoglobin (HbA1c) and co-morbidities. Comparing the estimated risk rate according to the different functions, Italian algorithms were more consistent with observed data; however, Progetto Cuore and Riskard show underestimation of events when applied to females.

CONCLUSIONS

Estimation of cardiovascular risk is dependent on the algorithm adopted and on the baseline risk of the reference cohort. Functions designed for a specific population, including risk variables peculiar for diabetes, should be adopted to increase the performance of such functions which is clearly unsatisfactory at present.

Pulmonary vascular response patterns during exercise in left ventricular systolic dysfunction predict exercise capacity and outcomes

BACKGROUND

Elevated resting pulmonary arterial pressure (PAP) in patients with left ventricular systolic dysfunction (LVSD) purports a poor prognosis. However, PAP response patterns to exercise in LVSD and their relationship to functional capacity and outcomes have not been characterized.

METHODS AND RESULTS

Sixty consecutive patients with LVSD (age 60±12 years, left ventricular ejection fraction 0.31±0.07, mean±SD) and 19 controls underwent maximum incremental cardiopulmonary exercise testing with simultaneous hemodynamic monitoring. During low-level exercise (30 W), LVSD subjects, compared with controls, had greater augmentation in mean PAPs (15±1 versus 5±1 mm Hg), transpulmonary gradients (5±1 versus 1±1 mm Hg), and effective pulmonary artery elastance (0.05±0.02 versus -0.03±0.01 mm Hg/mL, P<0.0001 for all). A linear increment in PAP relative to work (0.28±0.12 mm Hg/W) was observed in 65% of LVSD patients, which exceeded that observed in controls (0.07±0.02 mm Hg/W, P<0.0001). Exercise capacity and survival was worse in patients with a PAP/watt slope above the median than in patients with a lower slope. In the remaining 35% of LVSD patients, exercise induced a steep initial increment in PAP (0.41±0.16 mm Hg/W) followed by a plateau. The plateau pattern, compared with a linear pattern, was associated with reduced peak Vo(2) (10.6±2.6 versus 13.1±4.0 mL · kg(-1) · min(-1), P=0.005), lower right ventricular stroke work index augmentation with exercise (5.7±3.8 versus 9.7±5.0 g/m(2), P=0.002), and increased mortality (hazard ratio 8.1, 95% CI 2.7 to 23.8, P<0.001).

CONCLUSIONS

A steep increment in PAP during exercise and failure to augment PAP throughout exercise are associated with decreased exercise capacity and survival in patients with LVSD, and may therefore represent therapeutic targets.

CLINICAL TRIAL INFORMATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00309790.

Beta-thalassemia cardiomyopathy: history, present considerations, and future perspectives

Beta-thalassemia is an inherited hemoglobin disorder resulting in chronic hemolytic anemia that typically requires life-long transfusion therapy. Although traditionally prevalent in the Mediterranean basin, Middle East, North India, and Southeast Asia, immigration of those populations to North America and Western Europe has rendered beta-thalassemia a global health problem. Cardiac complications represent the primary cause of mortality and one of the major causes of morbidity in those patients. Heart disease is mainly expressed by a particular cardiomyopathy that progressively leads to heart failure and death. The beta-thalassemia cardiomyopathy is mainly characterized by 2 distinct phenotypes, a dilated phenotype, with left ventricular dilatation and impaired contractility and a restrictive phenotype, with restrictive left ventricular filling, pulmonary hypertension, and right heart failure. The pathophysiology of the disorder is multifactorial, with a central role of myocardial iron overload and the significant contribution of immunoinflammatory mechanisms. Patients' management is demanding and requires a multidisciplinary approach, preferably in specialized centers.

Endothelium-specific overexpression of human IC53 downregulates endothelial nitric oxide synthase activity and elevates systolic blood pressure in mice

AIMS

Hypertension is one of the major risk factors for cardiovascular diseases. Endothelial cells (ECs) exert important functions in the regulation of blood pressure. A novel gene, IC53, as an isoform of the cyclin-dependent kinase (CDK)-binding protein gene C53, is mainly expressed in vascular ECs and is upregulated in the failing heart of rats. Overexpression of IC53 promotes proliferation of ECs. To examine whether IC53 plays a role in the regulation of vascular tone and blood pressure, we constructed a transgenic (tg) mouse model of the IC53 gene and studied its phenotypes relevant to vascular function.

METHODS AND RESULTS

IC53 cDNA was cloned from a human aorta cDNA library. Using the endothelium-specific VE-cadherin promoter, we constructed tg mice in which IC53 was specifically overexpressed in vascular endothelia and found that the tg mice exhibit elevated systolic blood pressure (SBP) in contrast to the wild-type (wt) controls. Further studies revealed impaired endothelium-dependent vasodilation, reduced nitric oxide (NO) production and decreased endothelial NO synthase (eNOS) expression, and activity in the tg mice. Inhibition of IC53 in human umbilical vein ECs induces upregulation of eNOS activity.

CONCLUSION

Our results indicate that IC53 participates in the regulation of vascular homeostasis. Endothelium-specific overexpression of IC53 is associated with elevated SBP, which may be in part attributed to the downregulation of eNOS signalling.

Inducible nitric oxide synthase activity does not contribute to the maintenance of peripheral vascular tone in patients with heart failure

Enhanced iNOS (inducible nitric oxide synthase) activity may contribute to vascular dysfunction in patients with heart failure. In the present study, we aimed to determine whether iNOS activity contributes to the maintenance of vascular tone in patients with symptomatic heart failure with the use of the highly selective iNOS inhibitor 1400W {N-[3-(aminomethyl)benzyl] acetamidine}. Bilateral forearm blood flow was measured using venous occlusion plethysmography in 12 patients with New York Heart Association class II-IV heart failure and eight matched healthy control subjects during intra-brachial infusion of 1400W (0.1-1 micromol/min), L-NMMA (N(G)-monomethyl-L-arginine; a non-selective NOS inhibitor; 2-8 micromol/min) and noradrenaline (control vasoconstrictor; 60-480 pmol/min). In both patients and controls, intra-brachial infusion of L-NMMA and noradrenaline caused a dose-dependent reduction in infused forearm blood flow (P<0.05 for both): peak reduction of 32+/-6% and 37+/-4% during L-NMMA and 52+/-6% and 49+/-5% during noradrenaline respectively (P values were not significant when patients were compared with controls). In contrast, 1400W had no effect on blood flow at 1 micromol/min [-3+/-4% in patients (95% confidence intervals, -11 to 5%) and 3+/-8% in controls; P value was not significant]. In conclusion, we have demonstrated that intrabrachial selective iNOS inhibition does not influence forearm blood flow in patients with heart failure. We conclude that iNOS activity does not contribute to peripheral vascular tone in patients with symptomatic heart failure.

Vascular effects of a common gene variant of extracellular superoxide dismutase in heart failure

A common gene variant of human extracellular superoxide dismutase (ecSOD), in ∼5% of humans, is associated with increased risk of ischemic heart disease. The purpose of this study was to examine vascular effects of ecSOD with effects of the ecSOD variant (ecSODR213G) in rats with heart failure. Seven weeks after coronary artery ligation, we studied rats with heart failure and sham-operated rats. Adenoviral vectors expressing human ecSOD, ecSODR213G, or a control virus were injected intravenously. In the aorta from rats with heart failure, responses to acetylcholine (69 ± 4% relaxation, means ± SE) and basal levels of nitric oxide (NO) (vasoconstrictor responses to a NO synthase inhibitor) were greatly impaired, and levels of superoxide and peroxynitrite were increased. Gene transfer of ecSOD restored responses to acetylcholine (92 ± 2% relaxation) and basal levels of NO to normal and reduced levels of superoxide [from 2.3 ± 0.2 to 0.9 ± 0.2 relative light units per second per millimeter squared (RLU·s−1·mm−2)] and peroxynitrite (from 2.4 ± 0.2 to 0.9 ± 0.1 RLU·s−1·mm−2) in the aorta from rats with heart failure. Gene transfer of ecSODR213G produced little or no improvement. Responses to nitroprusside were not different among the groups. Expression of endogenous mRNA for SODs (CuZnSOD, MnSOD, and ecSOD) and endothelial NOS in the aorta was not different among the groups. In contrast to ecSOD, gene transfer of ecSODR213G in rats with heart failure has minimal beneficial effect on oxidative stress, endothelial function, or basal bioavailability of NO. We speculate that greatly diminished efficacy of ecSODR213G in protection against oxidative stress and endothelial dysfunction may contribute to increased risk of cardiovascular disease in humans with ecSODR213G.

Nicorandil but not ISDN Upregulates Endothelial Nitric Oxide Synthase Expression, Preventing Left Ventricular Remodeling and Degradation of Cardiac Function in Dahl Salt-sensitive Hypertensive Rats With Congestive Heart Failure

Cardiac endothelial nitric oxide synthase (ecNOS) was suppressed and inducible NOS (iNOS) enhanced at the decompensated heart failure stage in 18-week-old Dahl salt-sensitive (DS) hypertensive rats to which a high-salt diet had been administered from the age of 6 weeks. Nicorandil (NIC) enhanced ecNOS by activating Adenosine triphosphate-sensitive potassium channels (K-ATP channels) in the normal rat left ventricle. In this study, left ventricular hypertrophy, remodeling, function, cardiac ecNOS, and iNOS were compared between NIC and isosorbide dinitrate (ISDN) treatments in DS hypertensive rats with congestive heart failure. We examined DS hypertensive rats of 18 weeks of age to which 8% NaCl had been administered from the age of 6 weeks, and to which subdepressor doses of NIC (6 mg/kg/d), ISDN (6 mg/kg/d), and vehicle (CON) were administered from the age of 11 weeks. Contractility (Ees), stiffness (Eed), left ventricular end-diastolic volume, and left ventricular end-systolic volume were measured by conductance catheter and micromanometer on the basis of the pressure-volume relationship, and mRNA and protein levels of ecNOS and iNOS in the left ventricle were measured by reverse transcription-polymerase chain reaction and Western blot analysis at 18 weeks. LV mass index and LV dimensions were smaller in the NIC and ISDN groups than in the CON group (P < 0.01), and the first parameter was lower in the NIC than in the ISDN group (P < 0.01). Ees was also better maintained in the NIC and ISDN groups than in the CON group (NIC: 3349 +/- 649; ISDN: 2950 +/- 577, P < 0.05 vs. NIC; CON: 1424 +/- 375 mL/mmHg, P < 0.01 vs. treatments). Eed was exacerbated only in the ISDN group. NIC enhanced whereas ISDN suppressed ecNOS mRNA and protein levels (NIC 2.0-fold and 1.8-fold, ISDN 0.70-fold and 0.8-fold vs. CON; P < 0.01, respectively). However, no intragroup differences in iNOS mRNA or protein levels were observed for the 3 groups. More significant improvements in cardiac function and LV hypertrophy regression were observed in an NIC group than in an ISDN group of DS hypertensive rats. Activation of the K-ATP channel seems to induce this beneficial effect, which may be mediated in part by enhanced ecNOS expression in the heart in DS hypertensive congestive heart failure rat model.

Flow-mediated vasodilation predicts outcome in patients with chronic heart failure: comparison with B-type natriuretic peptide

OBJECTIVES

The aim of this study was to assess the predictive potency of impaired endothelium-dependent flow-mediated vasodilation (FMD) in patients with chronic heart failure (CHF).

BACKGROUND

Chronic heart failure is associated with reduced FMD; the prognostic impact of this observation is unknown.

METHODS

Seventy-five ambulatory CHF patients (United Network of Organ Sharing [UNOS] status 2) with a left ventricular ejection fraction (LVEF) < or =30%, despite optimized medical therapy (angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker, 100%; beta-blocker, 81%), were evaluated. Using high-resolution ultrasound, FMD of the brachial artery was assessed in addition to other neurohormonal, clinical, and hemodynamic variables. Age, gender, New York Heart Association (NYHA) functional class, LVEF, hemodynamic variables, B-type natriuretic peptide (BNP) levels, medical therapy, cardiovascular risk factors, and FMD were analyzed for prediction of the combined end point conversion to UNOS status 1 or death in a multivariate Cox model.

RESULTS

Up to three years, 21 patients (28%) converted to UNOS status 1, and 6 patients (8%) died. Univariate risk factors for the combined end point were log BNP (p = 0.0032), FMD (p = 0.0033), NYHA functional class (p = 0.0132), beta-blocker therapy (p = 0.0367), and mean blood pressure (p = 0.0406). In the multivariate analysis, only FMD (p = 0.0007), log BNP (p = 0.0032), and mean blood pressure (p = 0.0475) were independently related to the combined end point. In the Kaplan-Meier plot, significantly more patients with FMD <6.8% (median) reached the combined end point, as compared with patients with FMD >6.8% (p = 0.004).

CONCLUSIONS

In CHF, impaired FMD is a strong, independent predictor of conversion to UNOS status 1 or death.

MESENTERIC VASCULAR DYSFUNCTION AFTER CARDIOPULMONARY BYPASS WITH CARDIAC ARREST IS AGGRAVATED BY COEXISTENT HEART FAILURE

Although patients suffering from heart failure (HF) have an increased incidence of nonocclusive mesenteric ischemia after opened heart surgery, the impact of cardiopulmonary bypass with cardiac arrest (CPB) on mesenteric vascular circulation in such situation remains unexplored. Therefore, the present study investigates the effects of CPB on mesenteric vascular reactivity, regional metabolism, and oxidative stress in an experimental model of HF. Volume-overload HF was induced in six dogs by bilateral femoral arteriovenous fistula. Six sham-operated dogs were used as controls. Eight weeks later, the short-term effects of 90 min of CPB were assessed in vivo during acute experiments. The significant increase in left ventricular end-diastolic volume in HF animals did not influence the vasodilator response of the superior mesenteric artery to acetylcholine (ACH) and nitroprusside (SNP) under baseline conditions. However, reduced mesenteric oxygen delivery, increased oxygen extraction, and lactate release were found during CPB in the HF group. In addition, an increased free radical production was assessed in the HF group during (89 +/- 23 x 10 relative light units [RLU]) and after CPB (93 +/- 15 x 10 RLU) compared with controls (45 +/- 15 and 49 +/- 7 x 10 RLU, respectively). Finally, 90 min of CPB led to a more pronounced decrease of ACH- (-22% +/- 5% vs. -42% +/- 9%, P < 0.05) and SNP- (-14% +/- 4% vs. -50% +/- 7%, P < 0.002) induced mesenteric vasodilations in the HF group compared with controls. We conclude that coexistent HF significantly enhances the pathological effects of CPB on the mesenteric vascular circulation by additionally altering endothelial and smooth muscle vascular function consequent to augmented oxidative stress.

Deficiency of iNOS does not attenuate severe congestive heart failure in mice

Inducible nitric oxide synthase (iNOS) has been implicated in the pathophysiology of congestive heart failure (CHF). Given the extensive evidence supporting this concept, we hypothesized that iNOS deficiency (iNOS−/−) would attenuate the severity of CHF in mice. Mice were subjected to permanent occlusion [myocardial infarction (MI)] of the proximal left anterior descending coronary artery to produce CHF. Cardiac function was assessed in vivo using echocardiography and ultraminiature ventricular pressure catheters. Sham wild-type ( n = 17), sham iNOS−/− ( n = 8), MI wild-type ( n = 56), and MI iNOS−/− ( n = 48) mice were subjected to MI (or sham MI) and followed for 1 mo. Deficiency of iNOS did not alter survival during CHF compared with wild type (35% vs. 32%, P = not significant). Furthermore, fractional shortening and cardiac output were not significantly different between wild-type (9.6 ± 2.0% and 441 ± 20 μl·min−1·g−1) and iNOS−/− (9.8 ± 1.3% and 471 ± 26 μl·min−1·g−1) mice. The extent of cardiac hypertrophy and pulmonary edema was also similar between wild-type and iNOS−/− mice. None of the indexes demonstrated any significant differences between iNOS−/− and wild-type mice subjected to MI. These findings indicate that deficiency of iNOS does not significantly affect severe CHF in mice after MI.

Transcriptional Up-Regulation in Expression of 5-Hydroxytryptamine2A and Transcriptional Down-Regulation of Angiotensin II type 1 Receptors during Organ Culture of Rat Mesenteric Artery

The purpose of this study was to investigate in rat mesenteric artery if there is up-regulation of 5-hydroxytryptamine (5-HT) receptors and angiotensin II receptors and the potential role of protein kinase C activation in the smooth muscle cells during organ culture. Angiotensin II, 5-HT and potassium induced contraction of ring segments without endothelium, monitored by a sensitive in vitro pharmacology method. After the culture of the arterial ring segments for 24 hr, the concentration-contraction curves induced by 5-HT slightly shifted towards to the left with pEC(50) from 6.64+/-0.11 to 6.84+/-0.11 and a significant increase in E(max) from 147+/-11% to 246+/-15% (P<0.05), compared with that obtained in fresh segments. In contrast, the angiotensin II concentration-contraction curve only showed a significant decrease in E(max) from 99+/-10% to 37+/-8%. Specific antagonists for the 5-HT type 2A receptors (5-HT(2A)) and angiotensin II type 1 receptors (AT(1)) demonstrated that the contractions occurred via 5-HT(2A) and AT(1) receptors, respectively. Real-time PCR revealed that the 5-HT(2A) receptor mRNA was up-regulated in parallel with the contractile response while there was a down-regulation of AT(1) receptor mRNA. Transcriptional inhibitor actinomycin D and specific protein kinase C inhibitor Ro31-8220 demonstrated that it was a transcriptional mechanism with involvement of protein kinase C that regulated the enhanced expression of 5-HT(2A) receptors in the mesenteric artery.

Angiotensin II Receptor mRNA Expression and Vasoconstriction in Human Coronary Arteries: Effects of Heart Failure and Age

Angiotensin II is a potent vasoconstrictor that is implicated in the pathogenesis of hypertension, heart failure and atherosclerosis. In the present study, angiotensin II receptor mRNA expression levels were quantified by real-time polymerase chain reaction and the vasocontractile responses to angiotensin II were characterised by in vitro pharmacology in endothelium-denuded human coronary arteries. Angiotensin II type 1 (AT(1)) and type 2 (AT(2)) receptor mRNA expression levels were significantly down-regulated in arteries from patients with heart failure as compared to controls. The angiotensin II-induced vasoconstriction diminished with increasing age in patients with heart failure (r(2)=0.31, P<0.05). Also, the AT(1) receptor mRNA expression levels decreased with increasing age in patients with heart failure (r(2)=0.74, P<0.05), while no such correlation could be shown in the control group (r(2)=0.04, P=n.s.). The AT(2) receptor mRNA expression levels did not correlate with age in patients with heart failure or controls. In conclusion, the diminished angiotensin II vasoconstriction with age in heart failure patients is most likely due to a lower density of AT(1) receptors and may result from a longer period of exposure to heart failure in older patients.

Differences in tail vascular bed reactivity in rats with and without heart failure following myocardial infarction

Myocardial infarction (MI) was induced in rats by coronary ligation to compare changes in vascular reactivity from animals that developed heart failure (InfHF) with those that did not (Inf). Infarct size was similar in both groups. In vitro preparations of tail vascular bed were used to investigate the vascular responses to acetylcholine, sodium nitroprusside, and phenylephrine. Acetylcholine-induced relaxation was impaired in the Inf group (53 +/- 2%, n = 6) when compared with Sham (80 +/- 2%, n = 6, P < 0.05). The maximal response (E(max)) to phenylephrine increased in the Inf group (423 +/- 10 mm Hg, n = 9, P < 0.01) and decreased in InfHF (279 +/- 10 mm Hg, n = 7, P < 0.05) when compared with Sham (319 +/- 11 mm Hg, n = 8). Regardless of endothelial integrity, E(max) to phenylephrine increased in the Inf, nitro-l-arginine methyl ester, and indomethacin groups. An increased release of a prostanoid vasodilator was detected in the Inf group. Differently, the InfHF group presented a reduction of the E(max) to phenylephrine and an increment of nitric oxide release. This study demonstrates that MI without heart failure impairs endothelium-dependent relaxation and increases the reactivity to phenylephrine. This increase seems to involve a muscular component. The endothelium participates with an increased release of a vasodilator prostanoid, possibly to compensate the increased smooth muscle response. When heart failure follows MI, the reactivity to phenylephrine decreases, possibly due to an increased nitric oxide release.

The procyanidin-induced pseudo laminar shear stress response: a new concept for the reversal of endothelial dysfunction

Reduced endothelium-dependent vasodilator responses with increased synthesis of ET-1 (endothelin-1) are characteristics of endothelial dysfunction in heart failure and are predictive of mortality. Identification of treatments that correct these abnormalities may have particular benefit for patients who become refractory to current regimens. Hawthorn preparations have a long history in the treatment of heart failure. Therefore we tested their inhibitory effects on ET-1 synthesis by cultured endothelial cells. These actions were compared with that of GSE (grape seed extract), as the vasoactive components of both these herbal remedies are mainly oligomeric flavan-3-ols called procyanidins. This showed extracts of hawthorn and grape seed were equipotent as inhibitors of ET-1 synthesis. GSE also produced a potent endothelium-dependent vasodilator response on preparations of isolated aorta. Suppression of ET-1 synthesis at the same time as induction of endothelium-dependent vasodilation is a similar response to that triggered by laminar shear stress. Based on these results and previous findings, we hypothesize that through their pharmacological properties procyanidins stimulate a pseudo laminar shear stress response in endothelial cells, which helps restore endothelial function and underlies the benefit from treatment with hawthorn extract in heart failure.

Vasoactive mediators (VEGF and TNF-alpha) in patients with malignant and tuberculous pleural effusions

OBJECTIVE

Vascular endothelial growth factor (VEGF) is a potent endothelial cell-specific mitogen that promotes angiogenesis, vascular hyperpermeability, and vasodilatation by autocrine mechanisms involving nitric oxide (NO). This study was undertaken to determine the potential role of VEGF in the pathogenesis of pleural effusions, and its relationship with tumour necrosis factor (TNF)-alpha and NO in the pleural fluid and serum of patients with tuberculous and malignant pleural effusions.

METHODOLOGY

Pleural fluid and serum (SE) VEGF, TNF-alpha and NO levels were measured in 30 patients with exudative pleural effusion (15 with malignancies and 15 with tuberculosis). Control pleural fluid was obtained from 10 patients with transudative pleural effusion due to congestive heart failure and control serum samples were obtained from 10 healthy individuals. VEGF and TNF-alpha were measured by enzyme-linked immunosorbent assay and NO by a colorimetric method. Pleural biopsy, cytology or microbiological methods were used to make the final diagnosis.

RESULTS

In patients with exudative pleural effusions, the mean pleural fluid and serum VEGF levels and their ratios (P < 0.0001 for all) and TNF-alpha levels (P < 0.01, P < 0.0001 and P < 0.05) were significantly elevated compared to those with transudative pleural effusion. In malignant effusions, pleural fluid and serum VEGF levels were significantly elevated (P < 0.001 and P < 0.0001) while pleural fluid, and serum levels and their ratios of TNF-alpha (P < 0.001, P < 0.01 and P < 0.05) were significantly lower than those in tuberculosis. NO levels did not distinguish between tuberculous and malignant effusions.

CONCLUSIONS

In patients with malignant pleural effusions, levels of VEGF were significantly higher, while levels of TNF-alpha were significantly lower, than in patients with tuberculous effusions. In malignant pleural effusions, the elevated pleural fluid levels of VEGF and TNF-alpha are noteworthy. Our data support the hypothesis that blockade of VEGF, might benefit cancer patients with recurrent ascites or pleural fluid accumulation.

A nitric oxide‐releasing derivative of enalapril, NCX 899, prevents progressive cardiac dysfunction and remodeling in hamsters with heart failure

Nitric oxide (NO) production is known to be impaired in heart failure. A new compound (NCX 899), a NO-releasing derivative of enalapril was characterized, and its actions were evaluated in Bio 14.6 cardiomyopathic (CM) hamsters with heart failure. The hamsters were randomized to oral treatment for 4 weeks with vehicle (n=11), NCX 899 (NCX, 25 mg/kg, n=10), or enalapril (25 mg/kg, n=10). In the vehicle group, fractional shortening by echocardiography decreased (-23.6+/-2.0%) and LV end-diastolic dimension) increased (+10.9+/-1.0%), whereas fractional shortening increased (+17.5+/-4.4%) in NCX and was unchanged in the enalapril group (both P<0.01 vs. vehicle). End-diastolic dimension decreased only in NCX. LV contractility (LVdP/dt max and Emax) was significantly greater in NCX than in enalapril or vehicle, while relaxation (Tau) was shortened in both NCX and enalapril vs. vehicle. ACE activity was inhibited equally by NCX and enalapril in the CM hamster, and plasma nitrate levels were increased only in NCX (P<0.05 vs. enalapril and vehicle). In aortic strips endothelium-independent relaxation occurred only with NCX. The superior effects of NO-releasing enalapril (NCX) vs. enalapril alone to enhance vascular effects, increase LV contractility and prevent unfavorable remodeling and are consistent with vascular delivery of exogenous NO. NCX 899 may hold promise for the future treatment of heart failure.

Angiopoietin/tie-2 as mediators of angiogenesis: a role in congestive heart failure?

Angiogenic factors, in particular vascular endothelial growth factor (VEGF) and the angiopoietins, Ang-1 and -2, have recently generated significant interest, especially in oncology. The process of angiogenesis is also thought to occur in response to ischaemic conditions, which lie at the core of cardiovascular disease states such as coronary artery disease and congestive heart failure. However, current data do not conclusively show evidence of angiogenesis per se in these conditions, despite (for example) the presence of high levels of VEGF and Ang-2. High levels of these angiogenic factors in heart disease also have not translated into clinically significant new vessel formation, as in accelerated cancer growth or proliferative retinopathy. Indeed, we would hypothesize that these angiogenic markers--especially the angiopoietins--do not necessarily translate into new vessel formation in congestive heart failure (CHF), but may well reflect disturbances of endothelial integrity in CHF.

Increased peripheral resistance in heart failure: new evidence suggests an alteration in vascular smooth muscle function

Increased peripheral resistance is a hallmark of chronic heart failure and has been primarily attributed to neurohumoral pathways involving both the renin-angiotensin and sympathetic nervous systems. The increased resistance is thought to serve as a compensatory mechanism to help maintain perfusion to the vital organs by sustaining blood pressure in the fate of a failing heart. Local mechanisms, and in particular endothelial dysfunction, have also been shown to be important contributors in regulating arterial resistance and vascular remodeling in this disease. In this issue of the British Journal of Pharmacology, Gschwend et al. (2003) present new data suggesting that in the absence of a functional endothelium, myogenic constriction of small pressurized mesenteric arteries, an intrinsic property of vascular smooth muscle cells, is enhanced in a coronary artery ligation-induced myocardial infarction model of congestive heart failure (CHF) in the rat. The increased myogenic tone appears to be tightly linked to angiotensin II type 1 receptors (AT(1)). The possibility that CHF-induced stimulation of myogenic constriction is due to the local release of preformed angiotensin II or constitutive upregulation of the AT(1) receptor signaling pathways are discussed along with other potential cellular and molecular mechanisms previously suggested to play a role in myogenic reactivity.

Mechanisms of exercise training in patients with heart failure

BACKGROUND

The reduction of exercise capacity because of fatigue and dyspnea in patients with heart failure can be improved with exercise training. We sought to examine the mechanisms of exercise training as an adjunctive treatment strategy for patients with heart failure.

METHODS

We reviewed the published data on the possible mechanisms of effect of exercise training in heart failure.

RESULTS

Symptoms of heart failure may be explained on the basis of abnormal skeletal muscle perfusion and structure and endothelial function. Exercise training has been shown to engender changes in muscle structure and biochemistry and vascular function, although effects on cardiac function have not been detected uniformly and may require longer training periods.

CONCLUSIONS

A suitable, long-term program of exercise training may reverse unfavorable interactions among the heart, vessels, and skeletal muscles. These improvements may be preserved with an ongoing maintenance program.