Physical training improves endothelial function in patients with chronic heart failure

Central neural control of sympathetic nerve activity in heart failure following exercise training

Typical characteristics of chronic congestive heart failure (HF) are increased sympathetic drive, altered autonomic reflexes, and altered body fluid regulation. These abnormalities lead to an increased risk of mortality, particularly in the late stage of chronic HF. Recent evidence suggests that central nervous system (CNS) mechanisms may be important in these abnormalities during HF. Exercise training (ExT) has emerged as a nonpharmacological therapeutic strategy substitute with significant benefit to patients with HF. Regular ExT improves functional capacity as well as quality of life and perhaps prognosis in chronic HF patients. The mechanism(s) by which ExT improves the clinical status of HF patients is not fully known. Recent studies have provided convincing evidence that ExT significantly alleviates the increased sympathetic drive, altered autonomic reflexes, and altered body fluid regulation in HF. This review describes and highlights the studies that examine various central pathways involved in autonomic outflow that are altered in HF and are improved following ExT. The increased sympathoexcitation is due to an imbalance between inhibitory and excitatory mechanisms within specific areas in the CNS such as the paraventricular nucleus (PVN) of the hypothalamus. Studies summarized here have revealed that ExT improves the altered inhibitory pathway utilizing nitric oxide and GABA mechanisms within the PVN in HF. ExT alleviates elevated sympathetic outflow in HF through normalization of excitatory glutamatergic and angiotensinergic mechanisms within the PVN. ExT also improves volume reflex function and thus fluid balance in HF. Preliminary observations also suggest that ExT induces structural neuroplasticity in the brain of rats with HF. We conclude that improvement of the enhanced CNS-mediated increase in sympathetic outflow, specifically to the kidneys related to fluid balance, contributes to the beneficial effects of ExT in HF.

The role of exercise training in heart failure

Exercise training in patients with systolic heart failure (HF) is an accepted adjunct to an evidence-based management program. This review describes the pathophysiologic features that are thought to be responsible for the exercise intolerance experienced in the HF patient. Significant research has expanded our appreciation of the interplay of hemodynamic, ventilatory, and skeletal myopathic processes in this common, chronic condition. Randomized, controlled exercise trials designed to measure endothelial function, inflammatory markers, sympathetic neural activation, and skeletal muscle metabolism and structure have further defined the pathophysiology, documented the impact of exercise training on these processes, and confirmed the benefit of this therapy. Consistent with prior clinical research and patient experience are the recently published results of the HF-ACTION (Heart Failure-A Controlled Trial Investigating Outcomes of exercise TraiNing), which demonstrated a modest improvement in exercise capacity, reduction of symptoms, and improved self-reported measures of quality of life without adverse events. Consideration is given in this review to the benefits of variable intensity programs and the addition of resistance exercise to a standard aerobic prescription. Despite increasing validation of the role exercise training plays in the modification of exercise intolerance, challenges remain in its routine therapeutic application, including acceptance and use as an adjunctive intervention in the management of the patient with HF, limited insurance coverage for HF patients in cardiac rehabilitation, tailoring of exercise programs to best address the needs of subgroups of patients, and improved short- and long-term adherence to exercise training and a physically active lifestyle.

Superoxide dismutases: role in redox signaling, vascular function, and diseases

Excessive reactive oxygen species Revised abstract, especially superoxide anion (O₂•-), play important roles in the pathogenesis of many cardiovascular diseases, including hypertension and atherosclerosis. Superoxide dismutases (SODs) are the major antioxidant defense systems against (O₂•-), which consist of three isoforms of SOD in mammals: the cytoplasmic Cu/ZnSOD (SOD1), the mitochondrial MnSOD (SOD2), and the extracellular Cu/ZnSOD (SOD3), all of which require catalytic metal (Cu or Mn) for their activation. Recent evidence suggests that in each subcellular location, SODs catalyze the conversion of (O₂•-), H2O2, which may participate in cell signaling. In addition, SODs play a critical role in inhibiting oxidative inactivation of nitric oxide, thereby preventing peroxynitrite formation and endothelial and mitochondrial dysfunction. The importance of each SOD isoform is further illustrated by studies from the use of genetically altered mice and viral-mediated gene transfer. Given the essential role of SODs in cardiovascular disease, the concept of antioxidant therapies, that is, reinforcement of endogenous antioxidant defenses to more effectively protect against oxidative stress, is of substantial interest. However, the clinical evidence remains controversial. In this review, we will update the role of each SOD in vascular biologies, physiologies, and pathophysiologies such as atherosclerosis, hypertension, and angiogenesis. Because of the importance of metal cofactors in the activity of SODs, we will also discuss how each SOD obtains catalytic metal in the active sites. Finally, we will discuss the development of future SOD-dependent therapeutic strategies.

Effects of interval cycle training with or without strength training on vascular reactivity in heart failure patients

BACKGROUND

Exercise training confers beneficial effects on vascular reactivity in patients with chronic heart failure (CHF). This randomized study compares the effects of interval cycle training combined with strength training versus interval training alone on vascular reactivity in CHF patients.

METHODS

Twenty-eight consecutive stable CHF patients (23 males, 53 ± 10 years, 28.4 ± 4.1 kg/m(2), left ventricular ejection fraction of 37 ± 12%) were randomly assigned to 3 times' weekly training sessions for 3 months, consisting of a) 40 minutes of interval cycle training (n = 14), versus b) 20 minutes of similar interval training plus 20 minutes of strength training of the quadriceps, hamstrings, muscles of the shoulder and biceps brachialis (n = 14). The work/recovery ratio of each session was 30/60 seconds. The intensity of interval training was set at 50% of the peak workload achieved at the steep ramp test (consisted of a 25-Watt increase on a cycle ergometer every 10 seconds until exhaustion). All patients underwent maximal, symptom-limited cardiopulmonary exercise testing and ultrasound evaluation of vascular reactivity by flow-mediated vasodilation (FMD) before and after the program.

RESULTS

A significant improvement in FMD was observed in the combined training group (P = 0.002), in contrast to the interval training alone group (P = NS); the improvement was significantly greater in the combined training than in the interval training alone group (P < .05). Peak oxygen uptake increased significantly and similarly in both groups, in the interval training group (P = .03), and in the combined training group (P = .006). No significant correlation was found between FMD improvement and cardiopulmonary exercise parameters.

CONCLUSIONS

A combined high-intensity, interval cycle exercise with strength training induces a greater beneficial effect on vascular reactivity rather than interval exercise training alone in CHF patients.

Pathogenetic role of eNOS uncoupling in cardiopulmonary disorders

The homodimeric flavohemeprotein endothelial nitric oxide synthase (eNOS) oxidizes l-arginine to l-citrulline and nitric oxide (NO), which acutely vasodilates blood vessels and inhibits platelet aggregation. Chronically, eNOS has a major role in the regulation of blood pressure and prevention of atherosclerosis by decreasing leukocyte adhesion and smooth muscle proliferation. However, a disturbed vascular redox balance results in eNOS damage and uncoupling of oxygen activation from l-arginine conversion. Uncoupled eNOS monomerizes and generates reactive oxygen species (ROS) rather than NO. Indeed, eNOS uncoupling has been suggested as one of the main pathomechanisms in a broad range of cardiovascular and pulmonary disorders such as atherosclerosis, ventricular remodeling, and pulmonary hypertension. Therefore, modulating uncoupled eNOS, in particular eNOS-dependent ROS generation, is an attractive therapeutic approach to preventing and/or treating cardiopulmonary disorders, including protective effects during cardiothoracic surgery. This review provides a comprehensive overview of the pathogenetic role of uncoupled eNOS in both cardiovascular and pulmonary disorders. In addition, the related therapeutic possibilities such as supplementation with the eNOS substrate l-arginine, volatile NO, and direct NO donors as well as eNOS modulators such as the eNOS cofactor tetrahydrobiopterin and folic acid are discussed in detail.

The impact of exercise training on the diameter dilator response to forearm ischaemia in healthy men

AIM

Recent studies found differences between groups in the rate of diameter increase following the flow-mediated dilation (FMD). Whilst exercise training alters the magnitude of the FMD, little is known about the impact of exercise training on the rate of diameter increase. The aim of this study is to examine post-cuff deflation changes in brachial artery diameter following 5 min forearm ischaemia every 2 weeks across 8-weeks of a handgrip exercise training regimen.

METHODS

Post-deflation changes in brachial artery diameter following 5-min of ischaemia were examined before, after and every 2-weeks across an 8-week handgrip training programme in healthy young men (n = 11) using echo-Doppler.

RESULTS

The magnitude of dilation increased at week 2-4-6, but returned towards baseline values at week 8 (anova: P = 8.001). The time-to-peak diameter (42 ± 15s) demonstrated a significant prolongation at week 4 (77 ± 32s), but returned towards baseline values at weeks 6 and 8 (anova: P < 0.001). The rate of diameter increase did not differ across the intervention.

CONCLUSION

Exercise training in healthy subjects is initially characterized by a larger dilation. Since the rate of dilation did not change, a longer time-to-peak dilation was necessary to achieve the increase in magnitude of dilation. As exercise training continues, the timing and magnitude of the peak diameter response returns to near baseline levels.

The effects of progressive exercise on cardiovascular function in elite athletes: focus on oxidative stress

Some side-effects of excessive physical training are ascribed to reactive oxygen species production. In this work we investigated the effects of progressively imposed maximal physical effort (levels I to V), using progressive maximal exercise test, on peripheral blood lactate, NO (through NO2-), superoxide anion (O2-) and methemoglobin (MetHb) in a group of 19 elite soccer players. Blood lactate (mmol/L) was increased (4.55, level V vs. resting level, 1.95). The basal production of NO2- was in the direct relation with O2 consumption. Significant increase (p<0.05) in O2- values at effort level I (4.18) as compared to the resting value (4.01), and the significant increase (p<0.01 or p<0.05) in the MetHb (%) was found between II (18.79) and III (19.63) or between II and IV (19.24) effort levels, respectively. The regression lines of NO2- and O2- crossed at the level of the respiratory compensation point (RC), suggesting that RC could be of a crucial importance not only in the anaerobic and aerobic metabolism but in mechanisms of signal transductions as well. The results could be of the theoretical interest and also useful in designing an athlete training strategy.

Predictive value of serial assessment of endothelial function in chronic heart failure

BACKGROUND

It remains undefined whether reversibility of endothelial dysfunction after optimized therapies for heart failure (HF) provides prognostic information in patients with HF. This study examined whether changes in endothelial vasomotor function after therapies for HF may predict future outcomes in patients with stable HF.

METHODS

This study included 245 patients with stable chronic ischemic HF and an impaired flow-mediated dilation (FMD) of the brachial artery (FMD <5.5%). Measurement of FMD was repeated after 6 months for individualized and optimized therapy for HF and atherosclerotic risk factors. Patients were followed for 36 months or until the occurrence of cardiac death or hospitalization with decompensated HF.

RESULTS

FMD was persistently impaired (<5.5%) in 130 (53%) patients after 6 months of the optimized therapy, whereas it improved (FMD ≥5.5%) in the remaining 115 (47%) patients. During follow-up, an event occurred in 26 (20%) patients with persistently impaired FMD and in 7 (6%) patients with improved FMD (p<0.01). Multivariate Cox hazards analysis showed that persistent impairment of FMD was an independent predictor of cardiac events (hazard ratio 3.0, 95% CI 1.3-6.9, p=0.013). Persistently impaired FMD had a significantly incremental effect on the predictability of brain natriuretic peptide levels for cardiac events. Baseline FMD before the therapy for HF and atherosclerotic risk factors had no significant prognostic information.

CONCLUSIONS

Persistent endothelial vasomotor dysfunction despite therapies for HF and atherosclerotic risk factors was a predictor of cardiac events in patients with chronic ischemic HF.

Exercise training improves in vivo endothelial repair capacity of early endothelial progenitor cells in subjects with metabolic syndrome

BACKGROUND

Endothelial dysfunction and injury are considered to contribute considerably to the development and progression of atherosclerosis. It has been suggested that intense exercise training can increase the number and angiogenic properties of early endothelial progenitor cells (EPCs). However, whether exercise training stimulates the capacity of early EPCs to promote repair of endothelial damage and potential underlying mechanisms remain to be determined. The present study was designed to evaluate the effects of moderate exercise training on in vivo endothelial repair capacity of early EPCs, and their nitric oxide and superoxide production as characterized by electron spin resonance spectroscopy analysis in subjects with metabolic syndrome.

METHODS AND RESULTS

Twenty-four subjects with metabolic syndrome were randomized to an 8 weeks exercise training or a control group. Superoxide production and nitric oxide (NO) availability of early EPCs were characterized by using electron spin resonance (ESR) spectroscopy analysis. In vivo endothelial repair capacity of EPCs was examined by transplantation into nude mice with defined carotid endothelial injury. Endothelium-dependent, flow-mediated vasodilation was analysed using high-resolution ultrasound. Importantly, exercise training resulted in a substantially improved in vivo endothelial repair capacity of early EPCs (24.0 vs 12.7%; p < 0.05) and improved endothelium-dependent vasodilation. Nitric oxide production of EPCs was substantially increased after exercise training, but not in the control group. Moreover, exercise training reduced superoxide production of EPCs, which was not observed in the control group.

CONCLUSIONS

The present study suggests for the first time that moderate exercise training increases nitric oxide production of early endothelial progenitor cells and reduces their superoxide production. Importantly, this is associated with a marked beneficial effect on the in vivo endothelial repair capacity of early EPCs in subjects with metabolic syndrome.

Impact of exercise training and depression on survival in heart failure due to coronary heart disease

Depression is prevalent in patients with heart failure (HF) and is associated with increased mortality. In patients with coronary heart disease (CHD) without HF, exercise training (ET) can effectively decrease depressive symptoms resulting in improved survival. We evaluated 189 patients with American College of Cardiology/American Heart Association stage C HF due to CHD (mean left ventricular ejection fraction 35 ± 10%) enrolled in a structured ET program from January 2000 to December 2008, including a group of 151 who completed the program and 38 patients with HF who dropped out of rehabilitation without ET. Depressive symptoms were assessed by standard questionnaire at baseline and after ET, and mortality was determined at a mean follow-up of 4.6 ± 2.6 years. Prevalence of depressive symptoms decreased by 40% after ET, from 22% to 13% (p <0.0001). Patients initially classified as depressed who remained depressed after ET had nearly a fourfold higher mortality than patients whose depression resolved after ET (43% vs 11%, p = 0.005). Depressed patients who completed ET had a 59% lower mortality (44% vs 18%, p <0.05) compared to depressed dropout subjects not undergoing ET. Survival benefits after ET were concentrated to those patients with depression who improved exercise capacity. In conclusion, depressive symptoms are prevalent in patients with HF and are associated with increased mortality. Structured ET is effective in decreasing depressive symptoms, a factor that correlates with improved long-term survival.

Comparison of muscle functional electrical stimulation to conventional bicycle exercise on endothelium and functional status indices in patients with heart failure

The aim of this prospective, open-label, cohort study was to compare the effect of muscle functional electrical stimulation (FES) on endothelial function to that of conventional bicycle training. Eligible patients were those with New York Heart Association class II or III heart failure symptoms and ejection fractions ≤ 0.35. Two physical conditioning programs were delivered: FES of the muscles of the lower limbs and bicycle training, each lasting for 6 weeks, with a 6-week washout period between them. Brachial artery flow-mediated dilation (FMD) and other parameters were assessed before and after FES and the bicycle training program. FES resulted in a significant improvement in FMD, which increased from 5.9 ± 0.5% to 7.7 ± 0.5% (95% confidence interval for the difference 1.5% to 2.3%, p < 0.001). Bicycle training also resulted in a substantial improvement of endothelial function. FMD increased from 6.2 ± 0.4% to 9.2 ± 0.4% (95% confidence interval for the difference 2.5% to 3.5%, p < 0.001). FES was associated with a 41% relative increase in FMD, compared to 57% with bicycle exercise (95% confidence interval for the difference between the relative changes 1.2% to 30.5%, p = 0.034). This resulted in attaining a significantly higher FMD value after bicycle training compared to FES (9.2 ± 0.4% vs 7.7 ± 0.5%, p < 0.001). In conclusion, the effect of muscle FES in patients with heart failure on endothelial function, although not equivalent to that of conventional exercise, is substantial. Muscle FES protocols may prove very useful in the treatment of patients with heart failure who cannot or will not adhere to conventional exercise programs.

Arterial prehabilitation: can exercise induce changes in artery size and function that decrease complications of catheterization?

Coronary angiography and angioplasty are common invasive procedures in cardiovascular medicine, which involve placement of a sheath inside peripheral conduit arteries. Sheath placement and catheterization can be associated with arterial thrombosis, spasm and occlusion. In this paper we review the literature pertaining to the possible benefits of arterial 'prehabilitation'--the concept that interventions aimed at enhancing arterial function and size (i.e. remodelling) should be undertaken prior to cardiac catheterization or artery harvest during bypass graft surgery. The incidence of artery spasm, occlusion and damage is lower in larger arteries with preserved endothelial function. We conclude that the beneficial effects of exercise training on both artery size and function, which are particularly evident in individuals who possess cardiovascular diseases or risk factors, infer that exercise training may reduce complication rates following catheterization and enhance the success of arteries harvested as bypass grafts. Future research efforts should focus directly on examination of the 'prehabilitation' hypothesis and the efficacy of different interventions aimed at reducing clinical complications of common interventional procedures.

Combined exercise and cognitive behavioral therapy improves outcomes in patients with heart failure

OBJECTIVE

The purpose of this study is to compare the effectiveness of a combined 12-week home-based exercise (EX)/cognitive behavioral therapy (CBT) program (n=18) with CBT alone (n=19), EX alone (n=20), and with usual care (UC, n=17) in stable New York Heart Association Class II to III heart failure (HF) patients diagnosed with depression.

METHODS

Depressive symptom severity [Hamilton Rating Scale for Depression (HAM-D)], physical function [6-min walk test (6MWT)], and health-related quality of life (HRQOL) (Minnesota Living with Heart Failure Questionnaire) were evaluated at baseline (T1), after the 12-week intervention/control (T2), and following a 3-month telephone follow-up (T3). A repeated measures analysis of variance was used to determine group differences. Depression severity was dichotomized as minor (HAM-D, 11-14) and moderate-to-major depression (HAM-D, >/=15), and group intervention and control responses were also evaluated on that basis.

RESULTS

The greatest reduction in HAM-D scores over time occurred in the EX/CBT group (-10.4) followed by CBT (-9.6), EX (-7.3), and UC (-6.2), but none were statistically significant. The combined group showed a significant increase in 6-min walk distance at 24 weeks (F=13.5, P<.001). Among all groups with moderate-to-major depression, only those in CBT/EX had sustained lower HAM-D scores at 12 and 24 weeks, 6MWT distances were significantly greater at 12 (P=.018) and 24 (P=.013) weeks, and the greatest improvement in HRQOL also occurred.

CONCLUSIONS

Interventions designed to improve both physical and psychological symptoms may provide the best method for optimizing functioning and enhancing HRQOL in patients with HF.

Rapid vascular modifications to localized rhythmic handgrip training and detraining: vascular conditioning and deconditioning

Despite the evidence describing the rapid vascular function modifications to commencement and cessation of large muscle exercises (i.e. cycling), no studies examined the time-course vascular modifications to localized training and detraining. This study aimed to examine the effects of 4-week rhythmic handgrip exercise training and 2-week detraining on reactive hyperemic forearm blood flow and vascular resistance in 11 young men. Rhythmic handgrip exercise was performed in the non-dominant forearm for 20 min/day, 5 days/week, at 60% of maximum voluntary contraction for 4 weeks, followed by 2 weeks of no training. Forearm blood flow and vascular resistance were evaluated, in both arms, at rest and following arterial occlusion. These vascular function indices were obtained in five visits; before, after 1 and 4 week(s) of training as well as after 1 and 2 week(s) of training cessation. Resting cardiovascular measures were not altered during the study period. A 2 (arms) x 5 (visits) ANOVA revealed significant arms-by-visits interactions for reactive hyperemic forearm blood flow (p = 0.02) and vascular resistance (p = 0.02). Subsequent comparison demonstrated increased trained forearm reactive hyperemic blood flow 1 week after training, then returned to pre-training values 1 week following training cessation. In contrast, vascular resistance decreased 1 week after training commencement, only to return to pretraining level 1 week after training cessation. These results indicate a rapid, unilateral improvement in regional reactive hyperemic blood flow and vascular resistance following localized exercise-training. However, the improvements are transient and return to pretraining levels 1 week after detraining.

Bradykinin receptor blockade reduces sympathetic nerve response to muscle contraction in rats with ischemic heart failure

Previous animal and human studies have suggested that a muscle reflex engaged during contraction leads to heightened levels of sympathetic activity in congestive heart failure (CHF). The present experiment was designed to test the role for bradykinin, which is produced within contracting skeletal muscle and contributes to the muscle reflex through its action on kinin B(2) receptors located on the endings of thin fiber muscle afferents. CHF was induced in rats by myocardial infarction (MI) after coronary artery ligation. Echocardiography was performed to determine fractional shortening (FS), an index of the left ventricular function. In the decerebrate rats, we examined renal sympathetic nerve activity (RSNA) during 1 min intermittent (1 to 4 s stimulation to relaxation) contraction of left triceps surae muscles. RSNA responded synchronously as tension was developed, and the response was significantly (P < 0.05) greater in MI rats [+39 +/- 9% s(-1) (integrated RSNA over time); n = 16] with 20 +/- 2% of FS than that in control healthy rats (+19 +/- 2% s(-1); n = 16) with 49 +/- 2% of FS. Tension development did not differ significantly between the two groups of rats. Thirty minutes after intra-arterial injection into the hindlimb circulation of the kinin B(2) receptor antagonist, HOE-140 (2 microg/kg), the RSNA response to contraction was significantly reduced in the MI rats (+26 +/- 7% s(-1)) but not in the control rats (+17 +/- 2% s(-1)). These data suggest that bradykinin within contracting muscle is part of the exaggerated muscle reflex seen in CHF.

Impact of inactivity and exercise on the vasculature in humans

The effects of inactivity and exercise training on established and novel cardiovascular risk factors are relatively modest and do not account for the impact of inactivity and exercise on vascular risk. We examine evidence that inactivity and exercise have direct effects on both vasculature function and structure in humans. Physical deconditioning is associated with enhanced vasoconstrictor tone and has profound and rapid effects on arterial remodelling in both large and smaller arteries. Evidence for an effect of deconditioning on vasodilator function is less consistent. Studies of the impact of exercise training suggest that both functional and structural remodelling adaptations occur and that the magnitude and time-course of these changes depends upon training duration and intensity and the vessel beds involved. Inactivity and exercise have direct "vascular deconditioning and conditioning" effects which likely modify cardiovascular risk.

Impact of catheter insertion using the radial approach on vasodilatation in humans

The aim of this study was to determine the impact of catheter sheath insertion, a model of endothelium disruption in humans, on the conventional FMD (flow-mediated dilatation) response in vivo. Seventeen subjects undergoing transradial catheterization were recruited and assessed prior to, the day after, and 3–4 months postcatheterization. The catheter sheath's external diameter was 2.7 mm, and the average preprocedure internal radial artery diameter was 2.8 mm, indicating a high likelihood of endothelial denudation as a consequence of sheath placement. Radial artery flow-mediated and endothelium-derived NO (nitric oxide)-dependent function (FMD) was assessed within the region of sheath placement (sheath site) and also above the sheath (catheter site). GTN (glyceryl trinitrate) endothelium-independent NO-mediated function was also assessed distally. Measurements were made in both arms at all time points; the non-catheterized arm provided an internal control. Neither sheath (4.5±0.9%) nor catheter (4.4±0.9%) insertion abolished FMD, although both significantly decreased FMD from preintervention levels (9.0±0.8% sheath segment; 8.4±0.8% catheter segment; P<0.05). The impact of sheath and catheter placement on FMD was no longer evident after ~ 3 months recovery (8.0±1.5 and 8.1±1.7%, sheath and catheter, respectively). GTN responses also decreased from 14.8±1.7 to 7.9±1.0% (P<0.05) as a result of sheath placement, but values returned to baseline at ~ 3 months (13.0±1.8%). These results suggest that the presence of an intact, functional endothelial layer and consequent NO release may not be obligatory for some component of the FMD response. This raises the possibility of an endothelium-independent contribution to the flow-induced vasodilatation in humans.

Association between endothelial function and chronotropic incompetence in subjects with chronic heart failure receiving optimal medical therapy

OBJECTIVE

Impairment of flow-mediated, endothelium-dependent vasodilatation (FMD) of the brachial artery identifies peripheral endothelial dysfunction in subjects with chronic congestive heart failure (CHF) and is associated with increased morbidity and mortality. To further elucidate the interaction of peripheral and central mechanisms in the syndrome of CHF, we examined the association between endothelial function and chronotropic incompetence, an emerging prognostic marker in CHF.

METHODS

Thirty subjects with stable New York Heart Association (NYHA) functional class II-III CHF were studied. A vascular ultrasound study was performed to measure brachial artery FMD. The percentage of age-adjusted maximal predicted heart rate (MPHR) reached during cardiopulmonary exercise tolerance testing (CPETT) was used to assess the degree of chronotropic competence. All patients received ACE inhibitors and beta-adrenoceptor blockers.

RESULTS

Brachial artery FMD averaged 1.3 +/- 2.4% and age-adjusted % MPHR 74.1 +/- 11.7%. FMD correlated with % MPHR among all patients (r = 0.60, P = 0.01). FMD and resting heart rate (RHR) did not significantly correlate (r = 0.13, P = 0.55).

CONCLUSIONS

FMD, a measure of peripheral endothelial dysfunction, and % MPHR, a central determinant of cardiac output, are moderately correlated in heart failure patients receiving optimal medical therapy. Whether a cause-effect relationship underlies this association remains to be investigated.

Exercise-induced brachial artery vasodilation: effects of antioxidants and exercise training in elderly men

Aging, vascular function, and exercise are thought to have a common link in oxidative stress. Of the 28 subjects studied (young, 26 +/- 2 yr; old, 71 +/- 6 yr), 12 took part in a study to validate an antioxidant cocktail (AOC: vitamins C, E, and alpha-lipoic acid), while the remaining 8 young and 8 old subjects performed submaximal forearm handgrip exercise with placebo or AOC. Old subjects repeated forearm exercise with placebo or AOC following knee-extensor (KE) exercise training. Brachial arterial diameter and blood velocity (Doppler ultrasound) were measured at rest and during exercise. During handgrip exercise, brachial artery vasodilation in the old subjects was attenuated compared with that in young subjects following placebo (maximum = approximately 3.0 and approximately 6.0%, respectively). In contrast to the previously documented attenuation in exercise-induced brachial artery vasodilation in the young group with AOC, in the old subjects the AOC restored vasodilation (maximum = approximately 7.0%) to match the young. KE training also improved exercise-induced brachial artery vasodilation. However, in the trained state, AOC administration no longer augmented brachial artery vasodilation in the elderly, but rather attenuated it. These data reveal an age-related pro-/antioxidant imbalance that impacts vascular function and show that exercise training is capable of restoring equilibrium such that vascular function is improved and the AOC-mediated reduction in free radicals now negatively impacts brachial artery vasodilation, as seen in the young.

Reduced peripheral arterial blood flow with preserved cardiac output during submaximal bicycle exercise in elderly heart failure

BACKGROUND

Older heart failure (HF) patients exhibit exercise intolerance during activities of daily living. We hypothesized that reduced lower extremity blood flow (LBF) due to reduced forward cardiac output would contribute to submaximal exercise intolerance in older HF patients.

METHODS AND RESULTS

Twelve HF patients both with preserved and reduced left ventricular ejection fraction (LVEF) (aged 68 +/- 10 years) without large (aorta) or medium sized (iliac or femoral artery) vessel atherosclerosis, and 13 age and gender matched healthy volunteers underwent a sophisticated battery of assessments including a) peak exercise oxygen consumption (peak VO2), b) physical function, c) cardiovascular magnetic resonance (CMR) submaximal exercise measures of aortic and femoral arterial blood flow, and d) determination of thigh muscle area. Peak VO2 was reduced in HF subjects (14 +/- 3 ml/kg/min) compared to healthy elderly subjects (20 +/- 6 ml/kg/min) (p = 0.01). Four-meter walk speed was 1.35 +/- 0.24 m/sec in healthy elderly verses 0.98 +/- 0.15 m/sec in HF subjects (p < 0.001). After submaximal exercise, the change in superficial femoral LBF was reduced in HF participants (79 +/- 92 ml/min) compared to healthy elderly (222 +/- 108 ml/min; p = 0.002). This occurred even though submaximal stress-induced measures of the flow in the descending aorta (5.0 +/- 1.2 vs. 5.1 +/- 1.3 L/min; p = 0.87), and the stress-resting baseline difference in aortic flow (1.6 +/- 0.8 vs. 1.7 +/- 0.8 L/min; p = 0.75) were similar between the 2 groups. Importantly, the difference in submaximal exercise induced superficial femoral LBF between the 2 groups persisted after accounting for age, gender, body surface area, LVEF, and thigh muscle area (p

CONCLUSION

During CMR submaximal bike exercise in the elderly with heart failure, mechanisms other than low cardiac output are responsible for reduced lower extremity blood flow.

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Key Words Collapse

MESH Headings

• Age Factors
• Aged
• Aged, 80 and over
• Aorta, Thoracic/physiopathology
• Bicycling
• Cardiac Output
• Case-Control Studies
• Exercise Test
• Exercise Tolerance
• Female
• Femoral Artery/physiopathology
• Heart Failure/drug therapy
• Heart Failure/physiopathology
• Humans
• Iliac Artery/physiopathology
• Lower Extremity/blood supply
• Magnetic Resonance Imaging
• Male
• Middle Aged
• Muscle Contraction
• Muscle, Skeletal/blood supply
• Muscle, Skeletal/physiopathology
• Regional Blood Flow
• Stroke Volume
• Ventricular Function, Left

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Grants

• R37 AG018915 NIA NIH HHS
• R01 AG018915 NIA NIH HHS
• M01RR07122 NCRR NIH HHS
• R01 HL076438 NHLBI NIH HHS
• P30 AG021332 NIA NIH HHS
• R01HL076438 NHLBI NIH HHS
• P30AG21332 NIA NIH HHS
• R41AG030248 NIA NIH HHS
• R01AG18915 NIA NIH HHS

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Affiliation(s)

Chirapa Puntawangkoon Department of Internal Medicine - Cardiology Section, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, USA
Dalane W Kitzman Department of Internal Medicine - Cardiology Section, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, USA
Stephen B Kritchevsky Department of Internal Medicine - Geriatrics & Gerontology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, USA
Craig A Hamilton Department of Biomedical Engineering, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, USA
Barbara Nicklas Department of Human Genomics, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, USA
Xiaoyan Leng Department of Biostastical Sciences, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, USA Department of Public Health Sciences, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, USA
Peter H Brubaker Department of Health and Exercise Science, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, USA
W Gregory Hundley Department of Internal Medicine - Cardiology Section, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, USA Department of Radiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, USA

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Collaborators Collapse

Is exercise training an effective therapy targeting endothelial dysfunction and vascular wall inflammation?

There is an increasing evidence that endothelial dysfunction and vascular wall inflammation are present in all stages of atherosclerosis. Atherosclerosis does not have to necessarily progress to an acute clinical event. Several therapeutic strategies exist, such as exercise training, which mitigates endothelial dysfunction and inflammation. Exercise training consistently improves the nitric oxide bioavailability, and the number of endothelial progenitor cells, and also diminishes the level of inflammatory markers, namely pro-inflammatory cytokines and C-reactive protein. However, the mechanisms by which exercise improves endothelial function in coronary artery disease patients are not fully clarified. Several mechanisms have been proposed to explain the positive effect of exercise on the disease progression. They include the decrease in cytokine production by the adipose tissue, skeletal muscles, endothelial cells, and blood mononuclear cells, and also, the increase in the bioavailability of nitric oxide, antioxidant defences, and regenerative capacity of endothelium. This study aims to provide a critical review of the literature linking exercise, inflammation, and endothelial dysfunction in coronary artery patients, and to discuss the potential mechanisms behind the exercise-training improvement of endothelial function and inflammatory status.

Physical exercise improves the peripheral microcirculation of patients with chronic heart failure

PURPOSE

Patients with chronic heart failure (CHF) present with microcirculation alterations, partially attributed to endothelial dysfunction. Exercise training has been shown to induce beneficial effects in CHF patients. The aim of our study was to assess the effect of physical exercise on the microcirculation of CHF patients by near-infrared spectroscopy (NIRS).

METHODS

Sixteen consecutive stable CHF patients (men, n = 10; mean age = 50 +/- 12 years) participated in a 3-month rehabilitation program (3 sessions per week). All patients performed symptom-limited, ramp-incremental cardiopulmonary exercise testing on a cycle ergometer before and after the completion of the program. Measurements included peak oxygen uptake (VO2peak), VO2 at anaerobic threshold (AT), and first-degree slope of VO2 during the first minute of recovery (VO2/t slope). Tissue oxygen saturation was continuously measured by NIRS at the thenar muscle during a 3-minute vascular occlusion with a pneumatic cuff (occlusion technique) before and after the rehabilitation program.

RESULTS

The oxygen reperfusion rate (%/min) following the release of vascular occlusion increased significantly after the rehabilitation program (450 +/- 105 to 532 +/- 151, P = .004) as did vascular reactivity (from 27 +/- 13%/min to 39 +/- 21%/min, P = .006). In addition, there was a significant increase in VO2peak and AT (from 14.3 +/- 4.7 mL . kg . min to 16.7 +/- 6.3 mL . kg . min and from 9.5 +/- 3.6 mL . kg . min to 11.3 +/- 4 mL . kg . min, P = .007 and P = .012, respectively) as well as in VO2/t slope (from 0.35 +/- 0.17 to 0.51 +/- 0.07 mL . kg . min, P = .005).

CONCLUSIONS

Peripheral microcirculation of CHF patients measured by NIRS improved after the rehabilitation program. NIRS is a noninvasive technique that could be used to evaluate the effect of rehabilitation on the peripheral microcirculation of CHF patients.

Regulation of central angiotensin type 1 receptors and sympathetic outflow in heart failure

Angiotensin type 1 receptors (AT(1)Rs) play a critical role in a variety of physiological functions and pathophysiological states. They have been strongly implicated in the modulation of sympathetic outflow in the brain. An understanding of the mechanisms by which AT(1)Rs are regulated in a variety of disease states that are characterized by sympathoexcitation is pivotal in development of new strategies for the treatment of these disorders. This review concentrates on several aspects of AT(1)R regulation in the setting of chronic heart failure (CHF). There is now good evidence that AT(1)R expression in neurons is mediated by activation of the transcription factor activator protein 1 (AP-1). This transcription factor and its component proteins are upregulated in the rostral ventrolateral medulla of animals with CHF. Because the increase in AT(1)R expression and transcription factor activation can be blocked by the AT(1)R antagonist losartan, a positive feedback mechanism of AT(1)R expression in CHF is suggested. Oxidative stress has also been implicated in the regulation of receptor expression. Recent data suggest that the newly discovered catabolic enzyme angiotensin-converting enzyme 2 (ACE2) may play a role in the modulation of AT(1)R expression by altering the balance between the octapeptide ANG II and ANG- (1-7). Finally, exercise training reduces both central oxidative stress and AT(1)R expression in animals with CHF. These data strongly suggest that multiple central and peripheral influences dynamically alter AT(1)R expression in CHF.

Resistance training improves femoral artery endothelial dysfunction in aged rats

Although endurance exercise improves age-associated endothelial dysfunction, few studies have examined the effects of resistance training and the potential molecular mechanisms involved in altering vascular reactivity with age. Young (9 months) and aged (20 months) male, Fisher 344 rats were divided into four groups: Young Sedentary (YS, n = 14), Young Trained (YT, n = 10), Aged Sedentary (AS, n = 12), and Aged Trained (AT, n = 10). Resistance training consisted of climbing a 1 m wire ladder, at an 85 degrees angle, 3 days/week for 6 weeks with increasing weight added to the tail. Endothelial function in femoral arteries was determined by constructing acetylcholine dose-response curves on a wire myograph. Femoral artery phospho-Ser1179-eNOS, eNOS and Hsp90 expression were evaluated by Western blot. Acetylcholine-induced vasorelaxation was significantly (P < 0.05) impaired in AS compared to YS and YT but not AT compared to YS and YT. Phospho-Ser1179-eNOS and eNOS were elevated (P < 0.05) in aged animals but not changed with resistance training. Resistance training increased Hsp90 levels in both young and old animals. Therefore, resistance training improves age-associated endothelial dysfunction in femoral arteries without changes in eNOS phosphorylation and expression. Increased Hsp90 expression, a regulator of eNOS activity and coupling, suggests a potential mechanism for this improvement.

Prestroke physical activity and early functional status after stroke

BACKGROUND

The importance of physical activity as a modifiable risk factor for stroke in particular and cardiovascular disease in general is well documented. The effect of exercise on stroke severity and stroke outcomes is less clear. This study aimed to assess that effect.

METHODS

Data collected for patients enrolled in the Ischemic Stroke Genetics Study were reviewed for prestroke self-reported levels of activity and four measures of stroke outcome assessed at enrollment and approximately 3 months after enrollment. Logistic regression was used to assess the association between physical activity and stroke outcomes, unadjusted and adjusted for patient characteristics.

RESULTS

A total of 673 patients were enrolled; 50.5% reported aerobic physical activity less than once a week, 28.5% reported aerobic physical activity one to three times weekly, and 21% reported aerobic physical activity four times a week or more. Patients with moderate and high levels of physical activity were more likely to have higher Barthel Index (BI) scores at enrollment. A similar association was detected for exercise and good outcomes for the Oxford Handicap Scale (OHS). After 3 months of follow-up, moderate activity was still associated with a high BI score. No significant association was detected for activity and the OHS or Glasgow Outcome Scale at follow-up after adjustment for patient characteristics.

CONCLUSIONS

Higher levels of self-reported prestroke physical activity may be associated with functional advantages after stroke. Our findings should be seen as exploratory, requiring confirmation, ideally in a longitudinal study of exercise in an older population.

The role of nitric oxide in myocardial repair and remodeling

Nitric oxide (NO) plays a crucial role in many aspects of the pathophysiology of heart failure. NO is a double-edged sword; NO inhibits ischemia/reperfusion (I/R) injury, represses inflammation, and prevents left ventricular (LV) remodeling, whereas excess NO and co-existence of reactive oxygen species (ROS) with NO are injurious. The failing heart is exposed to not only oxidative stress by a plethora of humoral factors and inflammatory cells but also nitrosative stress. Activation of nitric oxide synthase (NOS) of any isoforms, [i.e., endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS)], concomitant with oxidative stress results in NOS uncoupling, leading to further oxidative/nitrosative stress. Indiscriminate removal of oxidative stress is not an effective means to prevent this detrimental process, because oxidative stress is necessary for an adaptive mechanism for cell survival against noxious stimuli. Therefore, removal of ROS in a site-specific manner or inhibition of the source of injurious ROS without affecting redox-sensitive survival signal transduction pathways represents a promising approach to elicit the beneficial effect of NO. Recent emerging pharmacological tools and regular exercise inhibit ROS generation in the proximity of NOSs, thereby increasing bioavailable NO and exerting cardioprotection against I/R injury and LV remodeling.

Physical activity during daily life and brachial artery flow-mediated dilation in peripheral arterial disease

We determined whether higher levels of physical activity in daily life are associated with better brachial artery flow-mediated dilation (FMD) among individuals with lower extremity peripheral arterial disease (PAD). Participants were 111 men and women with PAD (ankle-brachial index (ABI) Collapse

Key Words

• endothelial reactivity
• intermittent claudication
• peripheral arterial disease
• physical activity

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MESH Headings

• Activities of Daily Living
• Aged
• Aged, 80 and over
• Brachial Artery/diagnostic imaging
• Brachial Artery/physiopathology
• Cross-Sectional Studies
• Female
• Humans
• Hyperemia/physiopathology
• Lower Extremity/blood supply
• Male
• Middle Aged
• Monitoring, Ambulatory/instrumentation
• Peripheral Vascular Diseases/diagnostic imaging
• Peripheral Vascular Diseases/physiopathology
• Peripheral Vascular Diseases/therapy
• Recovery of Function
• Regional Blood Flow
• Resistance Training
• Time Factors
• Treatment Outcome
• Ultrasonography, Doppler
• United States
• Vasodilation
• Walking

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Grants

• R01 HL073351 NHLBI NIH HHS
• Z01 AG000015 Intramural NIH HHS
• R01-HL073351 NHLBI NIH HHS

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Affiliation(s)

Laila Payvandi Northwestern University Feinberg School of Medicine, Chicago, IL, USA
Alan Dyer
David McPherson
Philip Ades
James Stein
Kiang Liu
Luigi Ferrucci
Michael H Criqui
Jack M Guralnik
Donald Lloyd-Jones
Melina R Kibbe
Susan T Liang
Bonnie Kane
William H Pearce
Michael Verta
Walter J McCarthy
Joseph R Schneider
Adhir Shroff
Mary M McDermott

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Collaborators Collapse

Impact of shear rate modulation on vascular function in humans

Shear stress is an important stimulus to arterial adaptation in response to exercise and training in humans. We recently observed significant reverse arterial flow and shear during exercise and different antegrade/retrograde patterns of shear and flow in response to different types of exercise. The purpose of this study was to simultaneously examine flow-mediated dilation, a largely NO-mediated vasodilator response, in both brachial arteries of healthy young men before and after 30-minute interventions consisting of bilateral forearm heating, recumbent leg cycling, and bilateral handgrip exercise. During each intervention, a cuff inflated to 60 mm Hg was placed on 1 arm to unilaterally manipulate the shear rate stimulus. In the noncuffed arm, antegrade flow and shear increased similarly in response to each intervention (ANOVA; P<0.001, no interaction between interventions; P=0.71). Baseline flow-mediated dilation (4.6%, 6.9%, and 6.7%) increased similarly in response to heating, handgrip, and cycling (8.1%, 10.4%, and 8.9%, ANOVA; P<0.001, no interaction; P=0.89). In contrast, cuffed arm antegrade shear rate was lower than in the noncuffed arm for all of the conditions (P<0.05), and the increase in flow-mediated dilation was abolished in this arm (4.7%, 6.7%, and 6.1%; 2-way ANOVA: all conditions interacted P<0.05). These results suggest that differences in the magnitude of antegrade shear rate transduce differences in endothelial vasodilator function in humans, a finding that may have relevance for the impact of different exercise interventions on vascular adaptation in humans.

Training-induced increase in nitric oxide metabolites in chronic heart failure and coronary artery disease: an extra benefit of water-based exercises?

BACKGROUND

Rehabilitation programs involving immersed exercises are more and more frequently used, with severe cardiac patients as well.

DESIGN

This study investigated whether a rehabilitation program including water-based exercises has additional effects on the cardiovascular system compared with a traditional land-based training in heart disease patients.

METHODS

Twenty-four male stable chronic heart failure patients and 24 male coronary artery disease patients with preserved left ventricular function participated in the study. Patients took part in the rehabilitation program performing cycle endurance exercises on land. They also performed gymnastic exercises either on land (first half of the participants) or in water (second half). Resting plasma concentration of nitric oxide metabolites (nitrate and nitrite) and catecholamine were evaluated, and a symptom-limited exercise test on a cycle ergometer was performed before and after the rehabilitation program.

RESULTS

In the groups performing water-based exercises, the plasma concentration of nitrates was significantly increased (P = 0.035 for chronic heart failure and P = 0.042 for coronary artery disease), whereas it did not significantly change in the groups performing gymnastic exercise on land. No changes in plasma catecholamine concentration occurred.

CONCLUSION

In every group, the cardiorespiratory capacity of patients was significantly increased after rehabilitation. The water-based exercises seemed to effectively increase the basal level of plasma nitrates. Such changes may be related to an enhancement of endothelial function and may be of importance for the health of the patients.

Vascular endothelial function predicts mortality risk in patients with advanced ischaemic chronic heart failure

AIMS

Endothelial function is impaired in advanced chronic heart failure (ACHF) patients. We explored a possible association between endothelial function and subsequent mortality risk in ACHF.

METHODS AND RESULTS

We prospectively assessed brachial flow-mediated dilation (FMD) in 82 consecutive New York Heart Association class IV ischaemic ACHF patients with a mean left ventricular ejection fraction (LVEF) of 22 +/- 3%. Following overnight fasting and discontinuation of all medications for > or = 12 h, percent increase in FMD (%FMD) and nitroglycerin-mediated vasodilation were assessed using linear array ultrasound. All patients were followed for 14 +/- 2 months for adverse cardiovascular events, including death, hospitalization for CHF exacerbation, or myocardial infarction. Patients were divided into two groups: those with an FMD lesser than or equal to the median %FMD of 4.6% (n = 41) and those with an FMD above the median (n = 41). Both groups were comparable regarding cardiovascular risk factors, LVEF, and concomitant medications. During follow-up, 22 (53.6%) patients with FMD lesser than or equal to the median had composite adverse cardiovascular events compared with only eight patients (19.5%) with FMD above the median (P < 0.01). Furthermore, fiver deaths (12.1%) occurred in patients with FMD lesser than or equal to the median, compared with no deaths in patients with FMD above the median (P < 0.03). Cox regression analyses revealed that FMD was an independent predictor for these events.

CONCLUSION

Flow-mediated dilation is associated with increased mortality risk in ischaemic ACHF patients.

Endothelial progenitor cells and their potential clinical implication in cardiovascular disorders

Risk factors associated with cardiovascular diseases reduce the availability of endothelial progenitor cells (EPC) by affecting their mobilization and integration into injured vascular sites. The existence of a bone marrow reservoir of EPC has attracted interest, especially as target for therapeutic intervention in different pathological settings. Among the cardiovascular risk factors, hypertension has been shown to be a strongest predictor of EPC migratory impairment. However, at present, data concerning EPC biology are still limited. In this article we provide an overview of data relevant to their potential clinical implications in cardiovascular disorders. In addition, the recent advances in understanding the role of EPC in the pathophysiology of hypertension are discussed.

Trimetazidine potentiates the effects of exercise training in patients with ischemic cardiomyopathy referred for cardiac rehabilitation

BACKGROUND

Patients referred for cardiac rehabilitation may take advantage from combining trimetazidine (TMZ) with exercise training (ET), as both treatments produce similar effects in the cardiovascular system. It is, however, unknown whether the combination of TMZ with ET may determine greater improvements in functional capacity and endothelial function than ET alone.

DESIGN

A randomized longitudinal controlled study.

METHODS

We studied 116 patients (97 men and 19 women, mean age 58+/-9 years) with ischemic heart disease and left ventricular dysfunction who were referred for cardiac rehabilitation. Coronary risk factors were present in 82 patients (diabetes in 28 patients). Patients were randomized into three matched groups. A group (TMZ+training, TT, n=30) received TMZ at doses of 20 mg three times daily orally for 8 weeks in addition to standard medications and underwent a supervised program of ET at 60% of oxygen uptake at peak, three times a week for 8 weeks. A group (exercise, E, n=30) completed the ET program without receiving TMZ. A control group (C, n=26) was neither exercised nor received TMZ. A fourth group (TMZ, n=30) receiving TMZ 20 mg three times daily for 8 weeks was also studied. On study entry and at 8 weeks all patients underwent echocardiography, cardiopulmonary exercise testing, and vasomotor reactivity of the brachial artery.

RESULTS

Oxygen uptake at peak was significantly increased in the TT (25%), TMZ (15.1%), and E group (15.3%) (P<0.001 TT vs. C; P<0.05 vs. TMZ and E). Left ventricular ejection fraction was also improved in TT (18.4%), TMZ (15.7%), and E (12.9%) (P<0.001 TT vs. C; P<0.05 vs. TMZ and E), as a result of reduction in end-systolic volume. The endothelium-dependent dilation was similarly improved (P<0.001 TMZ vs. C; P<0.05 vs. TMZ and E). The most significant improvements were observed in the subgroup TT with multiple risk factors.

CONCLUSION

The addition of TMZ to ET determined greater improvements in functional capacity, left ventricular ejection fraction, and endothelium-dependent dilation than TMZ or ET given alone. No differences between improvements after TMZ and E as compared with controls were observed.

Effects of physical exercise on myocardial telomere-regulating proteins, survival pathways, and apoptosis

OBJECTIVES

The purpose of this study was to study the underlying molecular mechanisms of the protective cardiac effects of physical exercise.

BACKGROUND

Telomere-regulating proteins affect cellular senescence, survival, and regeneration.

METHODS

C57/Bl6 wild-type, endothelial nitric oxide synthase (eNOS)-deficient and telomerase reverse transcriptase (TERT)-deficient mice were randomized to voluntary running or no running wheel conditions (n = 8 to 12 per group).

RESULTS

Short-term running (21 days) up-regulated cardiac telomerase activity to >2-fold of sedentary controls, increased protein expression of TERT and telomere repeat binding factor (TRF) 2, and reduced expression of the proapoptotic mediators cell-cycle-checkpoint kinase 2 (Chk2), p53, and p16. Myocardial and leukocyte telomere length did not differ between 3-week- and 6-month-old sedentary or running mice, but telomerase activity, TRF2 and TERT expression were persistently increased after 6 months and the expression of Chk2, p53, and p16 remained down-regulated. The exercise-induced changes were absent in both TERT(-/-) and eNOS(-/-) mice. Running increased cardiac expression of insulin-like growth factor (IGF)-1. Treatment with IGF-1 up-regulated myocardial telomerase activity >14-fold and increased the expression of phosphorylated Akt protein kinase and phosphorylated eNOS. To test the physiologic relevance of these exercise-mediated prosurvival pathways, apoptotic cardiomyopathy was induced by treatment with doxorubicin. Up-regulation of telomere-stabilizing proteins by physical exercise in mice reduced doxorubicin-induced p53 expression and potently prevented cardiomyocyte apoptosis in wild-type, but not in TERT(-/-) mice.

CONCLUSIONS

Long- and short-term voluntary physical exercise up-regulates cardiac telomere-stabilizing proteins and thereby induces antisenescent and protective effects, for example, to prevent doxorubicin-induced cardiomyopathy. These beneficial cardiac effects are mediated by TERT, eNOS, and IGF-1.

Enhanced concentrations of relevant markers of nitric oxide formation after exercise training in patients with metabolic syndrome

Metabolic syndrome (MetS) denotes a clustering of risk factors that may affect nitric oxide (NO) bioavailability and predispose to cardiovascular diseases, which are delayed by exercise training. However, no previous study has examined how MetS affects markers of NO formation, and whether exercise training increases NO formation in MetS patients. Here, we tested these two hypotheses. We studied 48 sedentary individuals: 20 healthy controls and 28 MetS patients. Eighteen MetS patients were subjected to a 3-month exercise training (E+group), while the remaining 10 MetS patients remained sedentary (E-group). The plasma concentrations of nitrite, cGMP, and ADMA (asymmetrical dimethylarginine; an endogenous nitric oxide synthase inhibitor), and the whole blood nitrite concentrations were determined at baseline and after exercise training using an ozone-based chemiluminescence assay, and commercial enzyme immunoassays. Thiobarbituric acid reactive species (TBA-RS) were measured in the plasma to assess oxidative stress using a fluorometric method. We found that, compared with healthy subjects, patients with MetS have lower concentrations of markers of NO formation, including whole blood nitrite, plasma nitrite, and plasma cGMP, and increased oxidative stress (all P<0.05). Exercise training increased the concentrations of whole blood nitrite and cGMP, and decreased both oxidative stress and the circulating concentrations of ADMA (both P<0.05). These findings show clinical evidence for lower endogenous NO formation in patients with MetS, and for improvements in NO formation associated with exercise training in MetS patients.