Coronary inflammation by computed tomography pericoronary fat attenuation in young male anabolic androgenic steroid users

Background

The illicit use of anabolic androgenic steroids (AAS) has been associated with diminished cholesterol efflux mediated by HDL, remarkable decrease in high-density lipoprotein (HDL) plasma concentration and subclinical coronary artery disease (CAD). Inflammation is the key to the atherogenic process associated with atherosclerotic plaque vulnerability. The pericoronary mean fat attenuation (pFAM) has emerged as a marker of coronary inflammation and can predict future cardiovascular events, which is measurable from standard coronary computed tomography angiography (CCTA). However, whether AAS abuse has a role in pFAM in young male AAS users is unknown.

Purpose

The aim of this study was to evaluate whether AAS abuse could leads to higher pFAM and premature coronary inflammation in young male AAS users.

Methods

Twenty strength-trained AAS users (AASU) age 29±5 yr, 20 age-matched strength-trained AAS nonusers (AASNU), and 10 sedentary controls (SC) were enrolled in this study. Coronary inflammation was assessed by pFAM-CCTA in the right coronary artery (RCA), left anterior descending artery (LDA) and left circumflex coronary artery (Cx).

Results

pFAM in the RCA was significantly higher in AASU compared with AASNU and SC (−64.59±9.45 vs. −79.21±6.67 vs. −80.97±7,91 Hounsfield Units (HU), respectively, p<0.001]. Also, the pFAM in the LAD was higher in AASU compared with AASNU and SC (−72.83±7.21 vs. −79.41±6.72 vs. −80.97±7.72 HU, p=0.006). However, no difference to pFAM in the Cx between AASU, AASNU and SC (−74.30±5.85 vs. −79.77±7.13 vs. −78.19±5.82 HU, respectively, p=0.069) was found.

Conclusion

This study indicates that AAS abuse may be associated with higher pFAM and premature coronary inflammation in the RCA and LAD. The higher pFAM may be linked to early development of CAD in young AAS users.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Fundação Zerbini

Effect of exercise training on HDL subclasses and cholesterol transfers to HDL in elderly individuals

Introduction

Lifestyle habits play a crucial role on coronary artery disease (CAD) prevention. Exercise training promotes increase of HDL-C and decrease of plasma triglycerides is an important tool against atherogenesis. HDL-C determination evaluates only partially the HDL status and anti-atherosclerotic potential. A number of other parameters also relates HDL metabolism and function with CAD, such as HDL subclass distribution and cholesterol transfer to HDL, that have been reported as impaired in CAD. It is known that exercise training can improve those parameters in young individuals, but it has not been explored whether this effect can also be obtained in elderly subjects undergoing moderate training.

Purpose

Investigate the effects of regular practice of moderate exercise training on cholesterol transfer to HDL and HDL subclasses distribution in elderly compared to young subjects.

Methods

111 healthy subjects were enrolled in this study, as divided in four groups paired by sex: active elderly (AE, n=25), inactive elderly (IE, n=21), active young (AY, n=40) and inactive young (IY, n=25). All subjects performed cardiopulmonary test to determine VO2 peak and answered a questionnaire about exercise practice; only subjects practicing regular training for at least one year were selected to the 2 “active” groups. Blood samples were collected to determine lipid and apolipoprotein profile. Lipid subfractions were measured using the Lipoprint system. Cholesterol transfer to HDL was performed by incubating plasma with a donor lipoprotein-like nanoparticle containing radioactively labeled unesterified (UC) and esterified cholesterol (EC), followed by chemical precipitation and radioactive count.

Results

Data are shown on Table 1. Higher VO2 peak in both active groups confirmed the effectiveness of the training. HDL-C was higher in AE and AY than in IE and IY; apo A-I was higher in AY than in IY, but AE and IE were equal. UC transfer was higher in AE and AY than in IE and IY, but EC was higher AY than in IY, AE and IE were equal. Large HDL subfraction was higher in AY than in IY, but AE and IE were equal. The intermediate HDL subfraction was higher in AE than in IE. Comparing AE with AY, no differences in UC and EC, as well as HDL subfractions were observed.

Conclusion

Training had the ability to improve parameters of HDL metabolism not only in young but also in elderly subjects and it is remarkable that, despite their lower VO2 peak, in the AE group the cholesterol transfers and the HDL subfraction profile were similar to those of the AY group. Those results confirm the effectiveness of training to improve HDL anti-atherosclerotic features in the elderly.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Fundação de Amparo à Pesquisa do Estado de São Paulo

Association of sarcopenia and oxygen uptake efficiency slope in male patients with heart failure: The skeletal muscle hypothesis in practice

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Background

Sarcopenia, a generalized loss of muscle mass and function, is a common comorbidity in patients with heart failure (HF). The skeletal muscle, through afferent nerve pathways, modulates the respiratory response during physical efforts. However, whether ventilatory behavior is affected by the presence of sarcopenia is still unknown.

Purpose

To evaluate the impact of sarcopenia in ventilatory parameters of patients with HF.

Methods

We enrolled 169 male patients with stable chronic HF with left ventricular ejection fraction <40% (LVEF). Muscle strength was measured by handgrip dynamometer. Body composition was measured with dual-energy X-ray absorptiometry (DXA). Appendicular skeletal muscle (ASM) was comprised by lean muscle mass of both arms and legs. Sarcopenia was defined by handgrip strength and ASM/height2 lower than 27 kg and 7.0 kg/m2, respectively. Ventilation (VE), oxygen consumption (VO2), and carbon dioxide output (VCO2) were evaluated using breath-by-breath measurements during a cardiopulmonary exercise test performed on a cycle ergometer. Oxygen uptake efficiency slope (OUES) was calculated from data taken at exercise peak.

Results

Sarcopenia was identified in 29 patients (17.2%). Patients with sarcopenia had lower body mass index (BMI; 21.2±2.4 vs. 26.5±3.8 kg/m2, p<0.0001) with higher C-reactive protein [CRP; 12.4 (2.8-22.4) vs. 2.4 (1.0-6.3) mg/L, p<0.001] and brain natriuretic peptide [BNP; 949 (446-1722) vs. 374 (127-885) pg/mL, p<0.001] compared to patients without sarcopenia, respectively. At the first ventilatory threshold, VE/VO2 (36.9±5.9 vs. 32.7±6.5, p=0.003) and VE/VCO2 (39.8±7.2 vs. 35.3±6.9, p=0.004) were higher in sarcopenic patients compared to those without sarcopenia. At the exercise peak, comparing to patients without sarcopenia, sarcopenic patients had lower OUES (1,186±295 vs. 1,634±564, p<0.001), absolute VO2 (0.93±0.25 vs. 1.43±0.47 L/min, p<0.0001), relative VO2 (16.2±5.0 vs. 19.5±6.5 ml/kg/min, p=0.011), and VE (47.3±10.1 vs. 63.0±18.2 L/min, p<0.001), while VE/VCO2 (42.9±8.9 vs. 38.7±8.4, p=0.025) was increased and VE/VO2 (49.6±11.5 vs. 45.1±10.8, p=0.066) showed a tendency to be higher. OUES was positively correlated with total lean body mass (r=0.38; p<0.0001), ASM/height2 (r=0.36; p<0.0001), and handgrip strength (r=0.31; p<0.001). In a multivariate logistic regression model using OUES as the dependent variable, ASM/height2 (OR, 1.466; 95% CI, 1.003–2.141; p=0.048), haemoglobin (OR, 0.346; 95% CI, 0.135–0.886; p=0.027), and creatinine (OR, 0.391; 95% CI, 0.166–0.918; p=0.031) were independently associated with OUES adjusted by age, BMI, LVEF, BNP, CRP, and beta-blocker use.

Conclusion

Our results suggest that sarcopenia, possibly by reducing thoracic skeletal muscle mass or inefficiently modulating ventilation through afferent pathways, is related to impaired ventilatory response during exercise in patients with HF.

Lipid transfer to high-density lipoprotein is greater in elderly individuals with higher predictive cardiorespiratory fitness for age

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): FAPESP and CNPq

Background

Elderly individuals have higher coronary artery disease (CAD) risk. Triggering factors include diminished peak of oxygen consumption (VO2peak), commonly referred as cardiorespiratory fitness (CF), and increase in atherogenic lipid profile: non high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). The effect of aging on HDL-C is yet not clear, however, evaluating only the concentrations do not represent all HDL anti-atherosclerosis potential, aspects related to HDL metabolism and function can be more accurate to understand atherosclerosis process. Beyond that, elderly individuals also show reduced lipid transfer to HDL, an important assessment of HDL metabolism and function reported to be lower in CAD patients. Additionally, higher CF level is associated with longevity and lower hospitalizations rates and higher lipid transfer, independently of HDL-C. Data about different ages and absolute values of CF on lipids transfer are nonexistent. Purpose: To analyze the effect of paired CF absolute values and BMI in a healthy population of different ages on lipid transfer to HDL. Methods: 61 healthy individuals, enrolled in two groups: 30 young (27 ± 4 years, 21 females, BMI: 24.6 ± 2.6 kg/m², VO2peak: 33.9 ± 5.0 ml/kg/min) and 31 elderly (67 ± 5 years, 15 females, BMI: 23.9 ± 3.3 kg/m², VO2peak: 33.2 ± 4.5 ml/kg/min) that do not use any medication for chronic disease. Anthropometric data were collected. All participants performed treadmill cardiopulmonary test and the CF predictive value for age was calculated, according to each sex. Plasma lipids and cholesterol ester transfer protein (CETP) concentrations were determined. Lipid transfer was performed by incubating plasma with a donor lipoprotein-like nanoparticle containing radioactively labeled unesterified cholesterol (UC) and esterified cholesterol (EC), followed by chemical precipitation and radioactive count.  Cholesterol transfers from the donor nanoparticle to HDL are expressed as %. For the statistical analysis Student"s t and Mann-Whitney tests were used according to data distribution. Results: Waist circumference (p = 0.0291) and waist-hip ratio (p < 0.0001) were higher in elderly. LDL-C (p = 0.0005) and non HDL-C (p = 0.0003) were higher in elderly, as well apolipoprotein A-I, B, and CETP concentration. HDL-C and triglycerides were equal between groups. EC (p = 0.0268) and UC (p = 0.0348) transfers to HDL were higher in elderly. VO2peak predictive by age expressed in percentage was higher in elderly (90 ± 13 vs. 120 ±18; p < 0.0001). Conclusion: Elderly individuals show higher anthropometric data and concentrations of atherogenic cholesterol lipoproteins; however, HDL-C was equal. When paired by absolute CF values and BMI with young adults, elderly subjects with high CF predicted by age, have higher cholesterol transfer to HDL which demonstrates greater HDL metabolism.

Breast Cancer Promotes Cardiac Dysfunction Through Deregulation of Cardiomyocyte Ca2+-Handling Protein Expression That is Not Reversed by Exercise Training

Background

Patients treated for breast cancer have a high incidence of cardiovascular complications. In this study, we evaluated the impact of breast cancer on cardiac function and cardiomyocyte Ca²⁺‐handling protein expression. We also investigated whether exercise training (ET) would prevent these potential alterations.

Methods and Results

Transgenic mice with spontaneous breast cancer (mouse mammary tumor virus–polyomavirus middle T antigen [MMTV‐PyMT+], n=15) and littermate mice with no cancer (MMTV‐PyMT−, n=14) were studied. For the ET analysis, MMTV‐PyMT+ were divided into sedentary (n=10) and exercise‐trained (n=12) groups. Cardiac function was evaluated by echocardiography with speckle‐tracking imaging. Exercise tolerance test was conducted on a treadmill. Both studies were performed when the tumor became palpable and when it reached 1 cm³. After euthanasia, Ca²⁺‐handling protein expression (Western blot) was evaluated. Exercise capacity was reduced in MMTV‐PyMT+ compared with MMTV‐PyMT− (P_interaction=0.031). Longitudinal strain (P_group <0.001) and strain rate (P_group=0.030) were impaired. Cardiomyocyte phospholamban was increased (P=0.011), whereas phospho‐phospholamban and sodium/calcium exchanger were decreased (P=0.038 and P=0.017, respectively) in MMTV‐PyMT+. No significant difference in sarcoplasmic or endoplasmic reticulum calcium 2 ATPase (SERCA2a) was found. SERCA2a/phospholamban ratio was reduced (P=0.007). ET was not associated with increased exercise capacity. ET decreased left ventricular end‐systolic diameter (P_group=0.038) and end‐diastolic volume (P_group=0.026). Other morphological and functional cardiac parameters were not improved by ET in MMTV‐PyMT+. ET did not improve cardiomyocyte Ca²⁺‐handling protein expression.

Conclusions

Breast cancer is associated with decreased exercise capacity and subclinical left ventricular dysfunction in MMTV‐PyMT+, which is at least partly associated with dysregulation of cardiomyocyte Ca²⁺ handling. ET did not prevent or reverse these changes.

Adjuvant Treatment with 5-Fluorouracil and Oxaliplatin Does Not Influence Cardiac Function, Neurovascular Control, and Physical Capacity in Patients with Colon Cancer

BACKGROUND

Adjuvant chemotherapy with 5-fluorouracil (5-FU) and oxaliplatin increases recurrence-free and overall survival in patients with colon adenocarcinoma. It is known that these drugs have been associated with cardio- and neurotoxicity. We investigated the effects of 5-FU ± oxaliplatin on cardiac function, vascular responses, neurovascular control, and physical capacity in patients with colon cancer.

METHODS

Twenty-nine patients with prior colectomy for stage II-III adenocarcinoma and clinical indication for adjuvant chemotherapy were allocated to receive 5-FU (n = 12) or 5-FU + oxaliplatin (n = 17), according to the oncologist's decision. All the analyses were performed just before and after the end of chemotherapy. Cardiac function was assessed by echocardiography and speckle tracking, and cardiac autonomic control was assessed by heart rate variability (HRV). Vascular endothelial function was assessed by flow-mediated dilation (FMD). Muscle sympathetic nerve activity (MSNA) was directly recorded by microneurography technique, and muscle blood flow by venous occlusion plethysmography. Physical capacity was evaluated by cardiopulmonary exercise test.

RESULTS

Chemotherapy (pooled data) did not significantly change left ventricular ejection fraction (58 ± 1 vs. 55 ± 2%, p = .14), longitudinal strain (-18 ± 1 vs. -18 ± 1%, p = .66), and HRV. Likewise, chemotherapy did not significantly change FMD, muscle blood flow, and MSNA (33 ± 2 vs. 32 ± 1 bursts/min, p = .31). Physical capacity was not significantly changed in both groups. Similar findings were observed when the patients were subdivided in 5-FU and 5-FU + oxaliplatin treatment groups. 5-FU and 5-FU + oxaliplatin did not significantly change cardiac function, HRV, vascular responses, MSNA, and physical capacity.

CONCLUSION

This study provides evidence that adjuvant treatment with 5-FU ± oxaliplatin is well tolerated and does not promote changes compatible with long-term cardiotoxicity.

IMPLICATIONS FOR PRACTICE

Adjuvant chemotherapy with 5-fluorouracil (5-FU) and oxaliplatin increases recurrence-free and overall survival in patients with colon adenocarcinoma; however, these drugs have been associated with cardio- and neurotoxicity. This study investigated the effects of these drugs on cardiac function, vascular responses, neurovascular control, and physical capacity in patients with colon cancer. It was found that 5-FU and oxaliplatin did not significantly change cardiac function, cardiac autonomic control, vascular endothelial function, muscle sympathetic nerve activity, and physical capacity. This study provides evidence that adjuvant treatment with 5-FU ± oxaliplatin is well tolerated and does not promote changes compatible with long-term cardiotoxicity.

P331Effect of exercise stress test on platelet function in patients with recent acute myocardial infarction

Background

Exercise-based cardiac rehabilitation for coronary artery disease (CAD) is associated with lower cardiovascular mortality. On the other hand, acute strenuous exercise has been linked to cardiovascular complications such as acute myocardial infarction (AMI) and sudden cardiac death. One of the pathophysiological mechanisms involved in these outcomes might be an increase in platelet aggregability after exercise. Although previous studies showed higher platelet aggregability after exercise among stable CAD patients on aspirin treatment, there is no data regarding the effect of exercise on platelet activity in post-AMI patients on dual anti-platelet therapy (DAPT).

Purpose

To evaluate the effect of high-intensity exercise on platelet aggregability in sedentary post-AMI patients on DAPT.

Methods

Platelet function was analyzed immediately before and after maximal cardiopulmonary exercise test (CPET) on cycle ergometer utilizing a personalized ramp protocol and aiming to achieving peak exercise in around 10 min. The CPET was done within 31±4 days after uncomplicated AMI. Platelet aggregability was assessed by Multiplate®ADPtest (MP-ADP) and Multiplate® ASPItest (MP-ASPI) measured as area under the curve (AUC). Reticulated platelets were measured concomitantly to MP-ADP e MP-ASPI using a fully automated flow cytometer (Sysmex XN-2000®) to determine absolute immature platelet count (IPC) per 103/microliter. Continuous variables were expressed as means ±standard deviation or as median and 25th–75th percentiles if not Gaussian distributed. Comparisons between the pre- and post-CPET assessments were performed using Wilcoxon signed rank test.

Results

We analyzed 81 sedentary patients (mean age 58.3±10.1 years-old, 76.5% men) after AMI (50.6% with ST-elevation myocardial infarction, mean left ventricular ejection fraction after index event 55±11.7%, 98.8% on statin and 85.5% on beta-blocker treatment). Platelet aggregability, either by MP-ADP or MP-ASPI, and IPC were significantly increased after CPET (table).

Platelet function after CPET Before CPET After CPET p-value Multiplate® ADPtest (AUC) – median (25th–75th percentiles) 32.0 (22.0–48.5) 37.0 (26.0–55.2) 0.003 Multiplate® ASPItest (AUC) – median (25th–75th percentiles) 17.0 (12.7–22.0) 22.0 (16.7–28.0) <0.001 Immature platelet count (103/microliter) – median (25th–75th percentiles) 9.5 (6.8–13.8) 9.6 (6.6–16.5) 0.006 CPET: cardiopulmonary exercise test; AUC: area under the curve.

Conclusion

On this post-AMI population, platelet was hyperactivated after exercise stress test despite the use of DAPT. These findings suggest that, even when properly treated, post-AMI patients might be at higher risk of ischemic complications after high-intensity exercises, reinforcing the importance of tailoring exercise prescription in this population.

Acknowledgement/Funding

Sao Paulo Research Foundation, FAPESP

P4539Android to gynoid fat ratio and its association with functional capacity in male patients with heart failure

Background

Obesity may have a protective role in patients with heart failure with reduced ejection fraction (HFrEF), a phenomenon known as obesity paradox. However, some patients can also present sarcopenic obesity with similar exercise intolerance as lean patients with muscle wasting. However, the impact of body fat distribution on exercise intolerance in HFrEF is unknown.

Purpose

To study the association between android to gynoid fat ratio and functional capacity (VO2 peak) in male patients with HFrEF.

Methods

We enrolled 118 male with HFrEF with left ventricular ejection fraction (LVEF) <40%, mean age of 56±7 years old. Body composition was measured with dual x-ray absorptiometry. Android and gynoid fat were measured and the ratio between them was calculated (A/G ratio). Appendicular lean mass (ALM) was calculated as the lean muscle mass of both arms and legs divided by the height squared. Sarcopenic obesity was defined according to Foundation for the National Institutes of Health criteria (ALM adjusted for body mass index <0.789 for men). Muscle strength was assessed using the handgrip dynamometer (cutoff point for sarcopenia was defined as proposed by European Working Group on Sarcopenia in Older People). Blood sample was used to measure metabolic and hormonal parameters.

Results

Of those 118 patients, 15 (12.7%) showed sarcopenic obesity. In our cohort, the median A/G ratio was 0.55. A/G ratio >0.55 was detected in 60 patients. Weight and BMI were higher in patients with A/G ratio >0.55 (P<0.001). Absolute peak VO2 was similar between patients with A/G ratio lower or higher than 0.55 (1.48±0.40 vs. 1.43±0.40 L/min, P=0.559), while relative peak VO2 was lower in patients with A/G ratio >0.55 (18.7±5.3 vs. 22.5±6.1 mL/kg/min, P<0.001). LVEF, total cholesterol, LDL, haemoglobin, and IGF-1 were similar between patients with A/G ratio lower or higher than 0.55 (P>0.05). On the other hand, HDL, total testosterone, free testosterone, and DHEA were lower in patients with A/G ratio >0.55 (P<0.05). Logistic regression analysis showed A/G Ratio >0.55 to be independently associated with reduced peak VO2 (L/min) adjusted for age, BMI, LVEF, presence of sarcopenia, anabolic hormones, and haemoglobin (odds ratio 3.895, 95% CI 1.030–14.730, p=0.045).

Conclusion

Our data suggest that body fat distribution, particularly android and gynoid fat composition, might have an important adverse role on functional capacity in male patients with HFrEF.

Acknowledgement/Funding

FAPESP #2016/24306-0 and 2016/24833-0

4096Additive effects of exercise training upon cognitive function in regular red wine consumers compared to abstainers

Background

Although regular red wine (RW) consumption and physical exercise (PE) exert cardiovascular protection a possible aditive effect of both is unknown, especially regarding cognition.

Purpose

To investigate the effects of supervised PE upon cognitive function in regular RW consumers compared to abstainers (Abs)

Methods

Cognitive function was assessed by functional Cerebral Magnetic Resonance Image (fMRI) through Stroop Color Word test (Stroop) for executive function and 2-back for working memory as well as neuropsychological tests (trails A, B and Stroop1). Seventy three healthy males, aged 59±5.9 (SD) years were divided into 4 groups: 37 Abs (17 with PE, 20 without) and 36 RW drinkers (17 with PE, 19 without) and then were randomized in the pre-PE phase, either to supervised PE for 3 months, 3x week/1h duration or no PE. Cardiopulmonary exercise test (CET) was performed before and after interventions. Plasma lipids and glucose also were measured.

Results

Drinkers ingested 19.8±10.3 (SD) gr of ethanol/day as RW for an average of 26.1±15.7 years and did not change their habits during the study period. In pre-PE phase RW drinkers showed lower execution times than Abs in neurophsychological tests (trails A and B and Stroop1) and higher accuracy in the 2-back test in fMRI (p<0.05 for both). Furthermore, in post intervention phase, RW consumers with PE showed a trend towards improvement in executive function (Stroop: % accuracy 92.5±9.2 vs 95.6±5.0, p=0.05) and reduction in execution time (21.9±6 vs 19±3.4; p=0.049) as well as in neuropsychological Stroop-2 (p<0.05).In parallel there were no changes in activated cerebral áreas in either group after PE. However, there was a negative correlation between peak VO2 and activated brain areas by fMRI (Expert Analysis Tool based on the Generalized Linear Model; p<0.05) in both Abs and drinkers.

In contrast, there were no significant changes in any cognition test among abstainers regardless of PE; also there were no changes in metabolic profile. PE induced significant increments in peak VO2 in all PE groups (p<0.05).

fMRI BOLD sign during 2-back test

Conclusion

Physical exercise induced further improvement in executive function and working memory in long term RW drinkers, while no effects occurred in abstainers. Such effect was correlated with global fitness, as assessed by peak VO2.

Acknowledgement/Funding

Fundação de Amparo à Pesquisa do Estado de São Paulo; Banco Bradesco SA

P4132Decreased myocardial native T1 times and impaired myocardial contractility in young anabolic androgenic steroids users

Background

Anabolic androgenic steroids (AAS) have been associated with several injuries on the cardiovascular system. AAS abuse may have a direct toxic effect on the myocardium that could lead to cardiac function and structure alterations. Clinical and forensic cases have been reported myocardial fibrosis in AAS users. Myocardial fibrosis increases the risk of heart failure and sudden death. However, recent studies did not show evidence of focal myocardial fibrosis and diffuse myocardial fibrosis in AAS users using T1-mapping techniques. Thus, it remains unclear the association between AAS and cardiac structure alterations.

Purpose

The aim of this study was to evaluate cardiac structure by cardiovascular magnetic resonance (CMR) imaging with late-gadolinium enhancement (LGE), cardiac T1-mapping and extracellular volume measurements (ECV). Additionally, we also evaluated the cardiac contractility by CMR and echocardiography in young AAS users.

Methods

Twenty strength-trained AAS users (AASU) age 29±5 yr, 20 age-matched strength-trained AAS nonusers (AASNU), and 10 sedentary controls (SC) were enrolled. Cardiac structure was assessed by LGE, native T1-mapping and ECV. Cardiac contractility was evaluated as cardiac strain measured by CMR (feature tracking imaging technique) and echocardiography (speckle tracking technique).

Results

Global native T1 times [753 (683–870) vs 916 (815–1239) vs 1205 (825–1242) ms, respectively, p=0.03], and native T1 times at the left ventricle mid-ventricular slice [813 (695–1096) vs 922 (825–1095) vs 1140 (840–1322) ms, respectively, p=0.03] were lower in AASU compared with AASNU and SC. Mid-ventricular ECV was similar between AASU, AASNU and SC (22±6 vs 23±4 vs 24±4%, respectively, p=0.37). Focal myocardial fibrosis was found in 2 individuals (11%) of AASU. The mid anteroseptal and mid inferoseptal were the most affected segments. The total estimated mass of the LV mass was 1.25 g (0.65%). Three participants of SC showed focal myocardial fibrosis. The mid anterolateral, mid inferolateral and mid inferomedial were the most affected segments. The total estimated mass of the LV mass was 3.43 g (2.30%). In contrast, none of the AASNU had myocardial fibrosis. By CMR, AASU showed a lower medial radial strain (30±8 vs. 38±6%, p<0.01), medial circumferential strain (−17±3 vs −20±2%, p<0.01) and global longitudinal strain (−17±3 vs −20±3%, p<0.01) compared with AASNU. Echocardiography also demonstrated a lower 4CH longitudinal strain in AASU compared with AASNU (−15.5±3 vs −18.3±2%, p=0.03). Moreover, the AASU shower a higher left ventricle mass compared with AASNU and SC (185±20 vs 130±17 vs 112±14 g, respectively, p<0.01).

Conclusion

This study indicates that AAS abuse may be associated with decreased myocardial native T1 times, impaired myocardial contractility and focal myocardial fibrosis. These myocardial structural and functional alterations may be associated to unadapted cardiac hypertrophy in young AAS users.

Acknowledgement/Funding

Fundação de Amparo à Pesquisa do Estado de São Paulo [FAPESP], Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes).

Exercise training improves neurovascular control and calcium cycling gene expression in patients with heart failure with cardiac resynchronization therapy

Heart failure (HF) is characterized by decreased exercise capacity, attributable to neurocirculatory and skeletal muscle factors. Cardiac resynchronization therapy (CRT) and exercise training have each been shown to decrease muscle sympathetic nerve activity (MSNA) and increase exercise capacity in patients with HF. We hypothesized that exercise training in the setting of CRT would further reduce MSNA and vasoconstriction and would increase Ca2+-handling gene expression in skeletal muscle in patients with chronic systolic HF. Thirty patients with HF, ejection fraction <35% and CRT for 1 mo, were randomized into two groups: exercise-trained (ET, n = 14) and untrained (NoET, n = 16) groups. The following parameters were compared at baseline and after 4 mo in each group: V̇o2 peak, MSNA (microneurography), forearm blood flow, and Ca2+-handling gene expression in vastus lateralis muscle. After 4 mo, exercise duration and V̇o2 peak were significantly increased in the ET group (P = 0.04 and P = 0.01, respectively), but not in the NoET group. MSNA was significantly reduced in the ET (P = 0.001), but not in NoET, group. Similarly, forearm vascular conductance significantly increased in the ET (P = 0.0004), but not in the NoET, group. The expression of the Na+/Ca2+ exchanger (P = 0.01) was increased, and ryanodine receptor expression was preserved in ET compared with NoET. In conclusion, the exercise training in the setting of CRT improves exercise tolerance and neurovascular control and alters Ca2+-handling gene expression in the skeletal muscle of patients with systolic HF. These findings highlight the importance of including exercise training in the treatment of patients with HF even following CRT.

Obstructive Sleep Apnea Impairs Postexercise Sympathovagal Balance in Patients with Metabolic Syndrome

STUDY OBJECTIVES

The attenuation of heart rate recovery after maximal exercise (ΔHRR) is independently impaired by obstructive sleep apnea (OSA) and metabolic syndrome (MetS). Therefore, we tested the hypotheses: (1) MetS + OSA restrains ΔHRR; and (2) Sympathetic hyperactivation is involved in this impairment.

DESIGN

Cross-sectional study.

PARTICIPANTS

We studied 60 outpatients in whom MetS had been newly diagnosed (ATP III), divided according to apnea-hypopnea index (AHI) ≥ 15 events/h in MetS + OSA (n = 30, 49 ± 1.7 y) and AHI < 15 events/h in MetS - OSA (n = 30, 46 ± 1.4 y). Normal age-matched healthy control subjects (C) without MetS and OSA were also enrolled (n = 16, 46 ± 1.7 y).

INTERVENTIONS

Polysomnography, microneurography, cardiopulmonary exercise test.

MEASUREMENTS AND RESULTS

We evaluated OSA (AHI - polysomnography), muscle sympathetic nerve activity (MSNA - microneurography) and cardiac autonomic activity (LF = low frequency, HF = high frequency, LF/HF = sympathovagal balance) based on spectral analysis of heart rate (HR) variability. ΔHRR was calculated (peak HR minus HR at first, second, and fourth minute of recovery) after cardiopulmonary exercise test. MetS + OSA had higher MSNA and LF, and lower HF than MetS - OSA and C. Similar impairment occurred in MetS - OSA versus C (interaction, P < 0.01). MetS + OSA had attenuated ΔHRR at first, second, and at fourth minute than did C, and attenuated ΔHRR at fourth minute than did MetS - OSA (interaction, P < 0.001). Compared with C, MetS - OSA had attenuated ΔHRR at second and fourth min (interaction, P < 0.001). Further analysis showed association of the ΔHRR (first, second, and fourth minute) and AHI, MSNA, LF and HF components (P < 0.05 for all associations).

CONCLUSIONS

The attenuation of heart rate recovery after maximal exercise is impaired to a greater degree where metabolic syndrome (MetS) is associated with moderate to severe obstructive sleep apnea (OSA) than by MetS with no or mild or no OSA. This is at least partly explained by sympathetic hyperactivity.

Effects of exercise training on neurovascular control and skeletal myopathy in systolic heart failure

Neurohormonal excitation and dyspnea are the hallmarks of heart failure (HF) and have long been associated with poor prognosis in HF patients. Sympathetic nerve activity (SNA) and ventilatory equivalent of carbon dioxide (VE/VO2) are elevated in moderate HF patients and increased even further in severe HF patients. The increase in SNA in HF patients is present regardless of age, sex, and etiology of systolic dysfunction. Neurohormonal activation is the major mediator of the peripheral vasoconstriction characteristic of HF patients. In addition, reduction in peripheral blood flow increases muscle inflammation, oxidative stress, and protein degradation, which is the essence of the skeletal myopathy and exercise intolerance in HF. Here we discuss the beneficial effects of exercise training on resting SNA in patients with systolic HF and its central and peripheral mechanisms of control. Furthermore, we discuss the exercise-mediated improvement in peripheral vasoconstriction in patients with HF. We will also focus on the effects of exercise training on ventilatory responses. Finally, we review the effects of exercise training on features of the skeletal myopathy in HF. In summary, exercise training plays an important role in HF, working synergistically with pharmacological therapies to ameliorate these abnormalities in clinical practice.

Molecular basis for the improvement in muscle metaboreflex and mechanoreflex control in exercise-trained humans with chronic heart failure

Previous studies have demonstrated that muscle mechanoreflex and metaboreflex controls are altered in heart failure (HF), which seems to be due to changes in cyclooxygenase (COX) pathway and changes in receptors on afferent neurons, including transient receptor potential vanilloid type-1 (TRPV1) and cannabinoid receptor type-1 (CB1). The purpose of the present study was to test the hypotheses: 1) exercise training (ET) alters the muscle metaboreflex and mechanoreflex control of muscle sympathetic nerve activity (MSNA) in HF patients. 2) The alteration in metaboreflex control is accompanied by increased expression of TRPV1 and CB1 receptors in skeletal muscle. 3) The alteration in mechanoreflex control is accompanied by COX-2 pathway in skeletal muscle. Thirty-four consecutive HF patients with ejection fractions <40% were randomized to untrained (n = 17; 54 ± 2 yr) or exercise-trained (n = 17; 56 ± 2 yr) groups. MSNA was recorded by microneurography. Mechanoreceptors were activated by passive exercise and metaboreceptors by postexercise circulatory arrest (PECA). COX-2 pathway, TRPV1, and CB1 receptors were measured in muscle biopsies. Following ET, resting MSNA was decreased compared with untrained group. During PECA (metaboreflex), MSNA responses were increased, which was accompanied by the expression of TRPV1 and CB1 receptors. During passive exercise (mechanoreflex), MSNA responses were decreased, which was accompanied by decreased expression of COX-2, prostaglandin-E2 receptor-4, and thromboxane-A2 receptor and by decreased in muscle inflammation, as indicated by increased miRNA-146 levels and the stable NF-κB/IκB-α ratio. In conclusion, ET alters muscle metaboreflex and mechanoreflex control of MSNA in HF patients. This alteration with ET is accompanied by alteration in TRPV1 and CB1 expression and COX-2 pathway and inflammation in skeletal muscle.

Personalized preventive medicine: genetics and the response to regular exercise in preventive interventions

Regular exercise and a physically active lifestyle have favorable effects on health. Several issues related to this theme are addressed in this report. A comment on the requirements of personalized exercise medicine and in-depth biological profiling along with the opportunities that they offer is presented. This is followed by a brief overview of the evidence for the contributions of genetic differences to the ability to benefit from regular exercise. Subsequently, studies showing that mutations in TP53 influence exercise capacity in mice and humans are succinctly described. The evidence for effects of exercise on endothelial function in health and disease also is covered. Finally, changes in cardiac and skeletal muscle in response to exercise and their implications for patients with cardiac disease are summarized. Innovative research strategies are needed to define the molecular mechanisms involved in adaptation to exercise and to translate them into useful clinical and public health applications.

Lack of β2 -adrenoceptors aggravates heart failure-induced skeletal muscle myopathy in mice

Skeletal myopathy is a hallmark of heart failure (HF) and has been associated with a poor prognosis. HF and other chronic degenerative diseases share a common feature of a stressed system: sympathetic hyperactivity. Although beneficial acutely, chronic sympathetic hyperactivity is one of the main triggers of skeletal myopathy in HF. Considering that β2 -adrenoceptors mediate the activity of sympathetic nervous system in skeletal muscle, we presently evaluated the contribution of β2 -adrenoceptors for the morphofunctional alterations in skeletal muscle and also for exercise intolerance induced by HF. Male WT and β2 -adrenoceptor knockout mice on a FVB genetic background (β2 KO) were submitted to myocardial infarction (MI) or SHAM surgery. Ninety days after MI both WT and β2 KO mice presented to cardiac dysfunction and remodelling accompanied by significantly increased norepinephrine and epinephrine plasma levels, exercise intolerance, changes towards more glycolytic fibres and vascular rarefaction in plantaris muscle. However, β2 KO MI mice displayed more pronounced exercise intolerance and skeletal myopathy when compared to WT MI mice. Skeletal muscle atrophy of infarcted β2 KO mice was paralleled by reduced levels of phosphorylated Akt at Ser 473 while increased levels of proteins related with the ubiquitin--proteasome system, and increased 26S proteasome activity. Taken together, our results suggest that lack of β2 -adrenoceptors worsen and/or anticipate the skeletal myopathy observed in HF.

Integrative effect of carvedilol and aerobic exercise training therapies on improving cardiac contractility and remodeling in heart failure mice

The use of β-blockers is mandatory for counteracting heart failure (HF)-induced chronic sympathetic hyperactivity, cardiac dysfunction and remodeling. Importantly, aerobic exercise training, an efficient nonpharmacological therapy to HF, also counteracts sympathetic hyperactivity in HF and improves exercise tolerance and cardiac contractility; the latter associated with changes in cardiac Ca²⁺ handling. This study was undertaken to test whether combined β–blocker and aerobic exercise training would integrate the beneficial effects of isolated therapies on cardiac structure, contractility and cardiomyocyte Ca²⁺ handling in a genetic model of sympathetic hyperactivity-induced HF (α_2A/α_2C- adrenergic receptor knockout mice, KO). We used a cohort of 5–7 mo male wild-type (WT) and congenic mice (KO) with C57Bl6/J genetic background randomly assigned into 5 groups: control (WT), saline-treated KO (KOS), exercise trained KO (KOT), carvedilol-treated KO (KOC) and, combined carvedilol-treated and exercise-trained KO (KOCT). Isolated and combined therapies reduced mortality compared with KOS mice. Both KOT and KOCT groups had increased exercise tolerance, while groups receiving carvedilol had increased left ventricular fractional shortening and reduced cardiac collagen volume fraction compared with KOS group. Cellular data confirmed that cardiomyocytes from KOS mice displayed abnormal Ca²⁺ handling. KOT group had increased intracellular peak of Ca²⁺ transient and reduced diastolic Ca²⁺ decay compared with KOS group, while KOC had increased Ca²⁺ decay compared with KOS group. Notably, combined therapies re-established cardiomyocyte Ca²⁺ transient paralleled by increased SERCA2 expression and SERCA2:PLN ratio toward WT levels. Aerobic exercise trained increased the phosphorylation of PLN at Ser¹⁶ and Thr¹⁷ residues in both KOT and KOCT groups, but carvedilol treatment reduced lipid peroxidation in KOC and KOCT groups compared with KOS group. The present findings provide evidence that the combination of carvedilol and aerobic exercise training therapies lead to a better integrative outcome than carvedilol or exercise training used in isolation.

Time delay of baroreflex control and oscillatory pattern of sympathetic activity in patients with metabolic syndrome and obstructive sleep apnea

The incidence and strength of muscle sympathetic nerve activity (MSNA) depend on the magnitude (gain) and latency (time delay) of the arterial baroreflex control (ABR). However, the impact of metabolic syndrome (MetS) and obstructive sleep apnea (OSA) on oscillatory pattern of MSNA and time delay of the ABR of sympathetic activity is unknown. We tested the hypothesis that MetS and OSA would impair the oscillatory pattern of MSNA and the time delay of the ABR of sympathetic activity. Forty-three patients with MetS were allocated into two groups according to the presence of OSA (MetS + OSA, n = 21; and MetS - OSA, n = 22). Twelve aged-paired healthy controls (C) were also studied. OSA (apnea-hypopnea index > 15 events/h) was diagnosed by polysomnography. We recorded MSNA (microneurography), blood pressure (beat-to-beat basis), and heart rate (EKG). Oscillatory pattern of MSNA was evaluated by autoregressive spectral analysis and the ABR of MSNA (ABRMSNA, sensitivity and time delay) by bivariate autoregressive analysis. Patients with MetS + OSA had decreased oscillatory pattern of MSNA compared with MetS - OSA (P < 0.01) and C (P < 0.001). The sensitivity of the ABRMSNA was lower and the time delay was greater in MetS + OSA compared with MetS - OSA (P < 0.001 and P < 0.01, respectively) and C (P < 0.001 and P < 0.001, respectively). Patients with MetS - OSA showed decreased oscillatory pattern of MSNA compared with C (P < 0.01). The sensitivity of the ABRMSNA was lower in MetS - OSA than in C group (P < 0.001). In conclusion, MetS decreases the oscillatory pattern of MSNA and the magnitude of the ABRMSNA. OSA exacerbates these autonomic dysfunctions and further increases the time delay of the baroreflex response of MSNA.

Obstructive sleep apnea is associated with increased chemoreflex sensitivity in patients with metabolic syndrome

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is often observed in patients with metabolic syndrome (MetS). In addition, the association of MetS and OSA substantially increases sympathetic nerve activity. However, the mechanisms involved in sympathetic hyperactivation in patients with MetS + OSA remain to be clarified. We tested the hypothesis that chemoreflex sensitivity is heightened in patients with MetS and OSA.

DESIGN

Prospective clinical study.

PARTICIPANTS

Forty-six patients in whom MetS was newly diagnosed (ATP-III) were allocated into: (1) MetS + OSA (n = 24, 48 ± 1.8 yr); and (2) MetS - OSA (n = 22, 44 ± 1.7 yr). Eleven normal control subjects were also studied (C, 47 ± 2.3 yr).

MEASUREMENTS

OSA was defined as an apnea-hypopnea index ≥ 15 events/hr (polysomnography). Muscle sympathetic nerve activity (MSNA) was measured by microneurography technique. Peripheral chemoreflex sensitivity was assessed by inhalation of 10% oxygen and 90% nitrogen (carbon dioxide titrated), and central chemoreflex sensitivity by 7% carbon dioxide and 93% oxygen.

RESULTS

Physical characteristics and MetS measures were similar between MetS + OSA and MetS - OSA. MSNA was higher in MetS + OSA patients compared with MetS - OSA and C (33 ± 1.3 versus 28 ± 1.2 and 18 ± 2.2 bursts/min, P < 0.05). Isocapnic hypoxia caused a greater increase in MSNA in MetS + OSA than MetS - OSA and C (P = 0.03). MSNA in response to hyperoxic hypercapnia was greater in MetS + OSA compared with C (P = 0.005). Further analysis showed a significant association between baseline MSNA and peripheral (P < 0.01) and central (P < 0.01) chemoreflex sensitivity. Min ventilation in response to hyperoxic hypercapnia was greater in MetS + OSA compared with C (P = 0.001).

CONCLUSION

OSA increases sympathetic peripheral and central chemoreflex response in patients with MetS, which seems to explain, at least in part, the increase in sympathetic nerve activity in these patients. In addition, OSA increases ventilatory central chemoreflex response in patients with MetS.

Exercise training improves neurovascular control and functional capacity in heart failure patients regardless of age

Background: Exercise training is a non-pharmacological strategy for treatment of heart failure. Exercise training improves functional capacity and quality of life in patients. Moreover, exercise training reduces muscle sympathetic nerve activity (MSNA) and peripheral vasoconstriction. However, most of these studies have been conducted in middle-aged patients. Thus, the effects of exercise training in older patients are much less understood. The present study was undertaken to investigate whether exercise training improves functional capacity, muscular sympathetic activation and muscular blood flow in older heart failure patients, as it does in middle-aged heart failure patients.

Design: Fifty-two consecutive outpatients with heart failure from the database of the Unit of Cardiovascular Rehabilitation and Physiology Exercise were divided by age (middle-aged, defined as 45–59 years, and older, defined as 60–75 years) and exercise status (trained and untrained).

Methods: MSNA was recorded directly from the peroneal nerve using the microneurography technique. Forearm Blood Flow (FBF) was measured by venous occlusion plethysmography. Functional capacity was evaluated by cardiopulmonary exercise test.

Results: Exercise training significantly and similarly increased FBF and peak VO2 in middle-aged and older heart failure patients. In addition, exercise training significantly and similarly reduced MSNA and forearm vascular resistance in these patients. No significant changes were found in untrained patients.

Conclusion: Exercise training improves neurovascular control and functional capacity in heart failure patients regardless of age.

Exercise training improves muscle vasodilatation in individuals with T786C polymorphism of endothelial nitric oxide synthase gene

Allele T at promoter region of the eNOS gene has been associated with an increase in coronary disease mortality, suggesting that this allele increases susceptibility for endothelial dysfunction. In contrast, exercise training improves endothelial function. Thus, we hypothesized that: 1) Muscle vasodilatation during exercise is attenuated in individuals homozygous for allele T, and 2) Exercise training improves muscle vasodilatation in response to exercise for TT genotype individuals. From 133 preselected healthy individuals genotyped for the T786C polymorphism, 72 participated in the study: TT ( n = 37; age 27 ± 1 yr) and CT+CC ( n = 35; age 26 ± 1 yr). Forearm blood flow (venous occlusion plethysmography) and blood pressure (oscillometric automatic cuff) were evaluated at rest and during 30% handgrip exercise. Exercise training consisted of three sessions per week for 18 wk, with intensity between anaerobic threshold and respiratory compensation point. Resting forearm vascular conductance (FVC, P = 0.17) and mean blood pressure ( P = 0.70) were similar between groups. However, FVC responses during handgrip exercise were significantly lower in TT individuals compared with CT+CC individuals (0.39 ± 0.12 vs. 1.08 ± 0.27 units, P = 0.01). Exercise training significantly increased peak VO2 in both groups, but resting FVC remained unchanged. This intervention significantly increased FVC response to handgrip exercise in TT individuals ( P = 0.03), but not in CT+CC individuals ( P = 0.49), leading to an equivalent FVC response between TT and CT+CC individuals (1.05 ± 0.18 vs. 1.59 ± 0.27 units, P = 0.27). In conclusion, exercise training improves muscle vasodilatation in response to exercise in TT genotype individuals, demonstrating that genetic variants influence the effects of interventions such as exercise training.

High levels of C-reactive protein are associated with reduced vagal modulation and low physical activity in young adults

The purpose of this study was to examine the relationship between cardiac autonomic control derived from heart rate variability (HRV), high-sensitivity C-reactive protein (hs-CRP) and physical activity (PA) levels measured using accelerometers. A total of 80 healthy university students volunteered to participate in this study (20.56 ± 0.82 years, 1.36 ± 1.5 mg/L of hs-CRP). The participants were divided into groups based on tertiles of hs-CRP. Analysis of covariance adjusted to PA was used to assess group differences in HRV. Associations between hs-CRP, HRV indices and PA were analyzed using Pearson's correlation. The participants at the highest tertile of hs-CRP (tertile 3) had lower cardiac vagal modulation (SDNN, tertile 1=78.05 ± 5.9,tertile 2=82.43 ± 5.9,tertile 3=56.03 ± 6.1; SD1, tertile 1=61.27 ± 5.3, tertile 2=62.93 ± 5.4, tertile 3=40.03 ± 5.5). In addition, vagal indices were inversely correlated with hs-CRP but positively correlated with PA (SDNN r=-0.320, SD1 r=-0.377; SDNN r=0.304, SD1 r=0.299; P<0.05). Furthermore, the most physically active subjects had lower levels of hs-CRP and the highest levels of vagal modulation.

Impact of gender on benefits of exercise training on sympathetic nerve activity and muscle blood flow in heart failure

AIMS

We compared the effects of exercise training on neurovascular control and functional capacity in men and women with chronic heart failure (HF).

METHODS AND RESULTS

Forty consecutive HF outpatients from the Heart Institute, University of Sao Paulo, Brazil were divided into the following four groups matched by age: men exercise-trained (n = 12), men untrained (n = 10), women exercise-trained (n = 9), women untrained (n = 9). Maximal exercise capacity was determined from a maximal progressive exercise test on a cycle ergometer. Forearm blood flow was measured by venous occlusion plethysmography. Muscle sympathetic nerve activity (MSNA) was recorded directly using the technique of microneurography. There were no differences between groups in any baseline parameters. Exercise training produced a similar reduction in resting MSNA (P = 0.000002) and forearm vascular resistance (P = 0.0003), in men and women with HF. Peak VO(2) was similarly increased in men and women with HF (P = 0.0003) and VE/VCO(2) slope was significantly decreased in men and women with HF (P = 0.0007). There were no significant changes in left-ventricular ejection fraction in men and women with HF.

CONCLUSION

The benefits of exercise training on neurovascular control and functional capacity in patients with HF are independent of gender.

Sympathetic hyperactivity differentially affects skeletal muscle mass in developing heart failure: role of exercise training

Sympathetic hyperactivity (SH) is a hallmark of heart failure (HF), and several lines of evidence suggest that SH contributes to HF-induced skeletal myopathy. However, little is known about the influence of SH on skeletal muscle morphology and metabolism in a setting of developing HF, taking into consideration muscles with different fiber compositions. The contribution of SH on exercise tolerance and skeletal muscle morphology and biochemistry was investigated in 3- and 7-mo-old mice lacking both alpha(2A)- and alpha(2C)-adrenergic receptor subtypes (alpha(2A)/alpha(2C)ARKO mice) that present SH with evidence of HF by 7 mo. To verify whether exercise training (ET) would prevent skeletal muscle myopathy in advanced-stage HF, alpha(2A)/alpha(2C)ARKO mice were exercised from 5 to 7 mo of age. At 3 mo, alpha(2A)/alpha(2C)ARKO mice showed no signs of HF and preserved exercise tolerance and muscular norepinephrine with no changes in soleus morphology. In contrast, plantaris muscle of alpha(2A)/alpha(2C)ARKO mice displayed hypertrophy and fiber type shift (IIA --> IIX) paralleled by capillary rarefaction, increased hexokinase activity, and oxidative stress. At 7 mo, alpha(2A)/alpha(2C)ARKO mice displayed exercise intolerance and increased muscular norepinephrine, muscular atrophy, capillary rarefaction, and increased oxidative stress. ET reestablished alpha(2A)/alpha(2C)ARKO mouse exercise tolerance to 7-mo-old wild-type levels and prevented muscular atrophy and capillary rarefaction associated with reduced oxidative stress. Collectively, these data provide direct evidence that SH is a major factor contributing to skeletal muscle morphological changes in a setting of developing HF. ET prevented skeletal muscle myopathy in alpha(2A)/alpha(2C)ARKO mice, which highlights its importance as a therapeutic tool for HF.

Exercise Training Improves the Depressed Sensitivity of the Baroreceptors in Spontaneously Hypertensive Rats

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We have previously demonstrated that low-intensity exercise traning (ET) diminishes blood pressure and partially restores the sensitivity of the baroreflex bradycardia and tachycardia that are depressed in spontaneously hypertensive rats (SHR). Presently, the influence of the exercise trainig (ET) on the afferent part of the baroreflex (baroreceptor function curve) and its implication on the baroreflex was analysed in SHR and in normal control rats (NCR). NCR and SHR were subdivided in sedentary (S) and ET groups: SHR-S (n=8) and SHR-ET (n=6), and NCR-S (n=8) and NCR-ET (n=8). ET was performed on treadmill, during 60 min, 5 days/wk, at 50% of VO 2 max, for 12 wk. Arterial baroreflex sensitivity was evaluated by bradycardiac responses to phenylephrine (0.5;1;2;4;8 and 16 μg/ml, i.v.) and tachycardiac responses to sodium nitroprusside (0.5;1;2;4;8 and 16 μg/ml, i.v.). Aortic baroreceptor function curve was evaluated under pentobarbital anesthesia (40 mg/kg) during rapid variations of arterial pressure (AT/CODAS, 3kHz per channel). The relationship between changes in baroreceptor discharge (0-100%) and systolic arterial pressure was analysed using a sigmoidal regression. Mean arterial pressure was reduced in SHR-ET compared to SHR-S group (165±7 vs. 183±4 mmHg) but remained inaltared in NCR-ET compared to NCR-S (112±3 vs. 115±3 mmHg). In SHR, ET increased the sensitivity of baroreflex bradycardia (1.9±0.1 vs. 0.7±0.1 bpm.mmHg -1 ) and tachycardia (2.9±0.1 vs. 1.8±0.2 bpm.mmHg -1 ) which were depressed. In NCR-ET baroreflex bradycardia was decreased (1.4±0.1 vs. 1.7±0.1 bpm.mmHg -1 ) but baroreflex tachycardia was increased (4.6±0.5 vs. 3.0±0.2 bpm.mmHg -1 ). ET increased the aortic baroreceptor gaing-sensitivity in both groups: SHR (0.9±0.1 vs. 0.7±0.1 %.mmHg -1 ) and NCR (2.1±0.1 vs. 1.4±0.1 %.mm Hg -1 ). Conclusion:1. ET increases aortic baroreceptor gain-sensitivity in NCR as well in SHR; 2. The improvement of the baroreflex produced by ET in SHR is partially explainedd by the recovery of the baroreceptor sensitivity, which may also participate in the reduction of high blood pressure.

Impaired endothelium-mediated vasodilation is not the principal cause of vasoconstriction in heart failure

The extent to which abnormal endothelium-dependent vasodilator mechanisms contribute to abnormal resting vasoconstriction and blunted reflex vasodilation seen in heart failure is unknown. The purpose of this study was to test the hypothesis that the resting and reflex abnormalities in vascular tone that characterize heart failure are mediated by abnormal endothelium-mediated mechanisms. Thirteen advanced heart-failure patients (New York Heart Association III-IV) and 13 age-matched normal controls were studied. Saline, acetylcholine (20 microg/min), or L-arginine (10 mg/min) was infused into the brachial artery, and forearm blood flow was measured by venous plethysmography at rest and during mental stress. At rest, acetylcholine decreased forearm vascular resistance in normal subjects, but this response was blunted in heart failure. During mental stress with intra-arterial acetylcholine or L-arginine, the decrease in forearm vascular resistance was not greater than during saline control in heart failure [saline control vs. acetylcholine (7 +/- 3 vs. 6 +/- 3, P = NS) or vs. L-arginine (9 +/- 2 units, P = NS)]. The increase in forearm blood flow was not greater than during saline control in heart failure [saline control vs. acetylcholine (1. 2 +/- 0.3 vs. 1.3 +/- 0.3, P = NS), or vs. L-arginine (1.2 +/- 0.2 ml x min(-1) x 100 ml(-1), P = NS)]. Furthermore, during mental stress with nitroprusside, the decrease in forearm vascular resistance was not greater than during saline control [saline control vs. nitroprusside (7 +/- 3 vs. 5 +/- 4 ml x min(-1) x 100 g(-1), P = NS)], and the increase in forearm blood flow was not greater than during saline control [saline control vs. nitroprusside (1.2 +/- 0.3 vs. 1.3 +/- 0.5 ml x min(-1) x 100 g(-1), P = NS)]. Because the endothelial-independent agent nitroprusside was unable to restore resting and reflex vasodilation to normal in heart failure, we conclude that impaired endothelium-mediated vasodilation with acetylholine-nitric oxide cannot be the principal cause of the attenuated resting- or reflex-mediated vasodilation in heart failure.

Impact of acute mental stress on sympathetic nerve activity and regional blood flow in advanced heart failure: implications for 'triggering' adverse cardiac events

BACKGROUND

Evidence is accumulating that specific "triggers," such as intense psychological stress, may precipitate myocardial infarction and sudden death. Patients with advanced heart failure have increased resting sympathoexcitation, which has been directly related to increased mortality. The impact of triggers on sympathetic nerve activity and regional blood flow in heart failure has not been examined in patients with heart failure.

METHODS AND RESULTS

Twenty-seven patients with heart failure (NYHA functional class III or IV) and 26 age-matched normal control subjects were studied. Muscle sympathetic nerve activity, heart rate, mean arterial pressure, forearm blood flow, and renal blood flow were measured during mental stress testing with mental arithmetic and Stroop color word test. Patients with heart failure had elevated levels of resting muscle sympathetic nerve activity and heart rate. Mental stress significantly increased muscle sympathetic nerve activity and heart rate in both patients with heart failure and control subjects, although the magnitude of increases tended to be blunted in patients with heart failure. Nevertheless, absolute levels of sympathetic activity in patients with heart failure remained significantly higher than levels in control subjects during mental stress. The decrease in renal blood flow in patients with heart failure was similar to that of control subjects, despite greater resting renal vasoconstriction. The increase in forearm blood flow during mental stress testing in patients with heart failure was blunted compared with that of control subjects.

CONCLUSIONS

Patients with heart failure do not have augmented muscle sympathetic nerve activity responses to mental stress, despite elevated resting levels of sympathetic activity, but they do have markedly higher absolute levels of sympathetic nerve activity during mental stress as well as at rest.

Left ventricular function during dynamic exercise in untrained and moderately trained subjects

The influence of exercise training on left ventricular function at rest (R), at anaerobic threshold (AT), and during peak exercise (PE) was evaluated in 12 healthy untrained and 13 trained (T) subjects who underwent Doppler echocardiography at R and radionuclide ventriculography at R and during exercise. The end-diastolic volume and stroke volume were significantly higher in the T group than in the untrained group at R. The ejection fraction rose significantly from R to AT and from AT to PE (80.0 +/- 0.84 vs. 83.6 +/- 0.91%), but no significant difference was observed between groups. The peak diastolic filling rate rose significantly during exercise, with a further significant increase observed in the T group (AT, 6.38 +/- 0.40 vs. 5.01 +/- 0.16 end-diastolic counts/s; PE, 8.24 +/- 0.42 vs. 7.15 +/- 0.35 end-diastolic counts/s). The percent variation of minimal systolic counts fell significantly at AT and PE in relation to R. Our data demonstrate that exercise training produces a significant increase in peak diastolic filling rate but no change in systolic function during exercise and that metabolic acidosis caused by exercise does not limit systolic function.

Vagal function impairment after exercise training

The present investigation was undertaken to evaluate the vagal function of trained (T) and sedentary (S) rats by use of different approaches in the same animal. After 13 wk of exercise training (treadmill for 1 h 5 times/wk at 26.8 m/min and 15% grade), T rats had a resting heart rate (HR) slightly but significantly lower than S rats (299 +/- 3 vs. 308 +/- 3 beats/min). T rats had marked reduction of the intrinsic HR (329 +/- 4 vs. 369 +/- 5 beats/min) after blockade by methylatropine and propranolol. They also exhibited depressed vagal and sympathetic tonus. Baroreflex bradycardia (phenylephrine injections) was reduced, bradycardic responses produced by electrical stimulation of the vagus were depressed, and responses to methacholine injection were decreased in T rats. Therefore several evidences of vagal function impairment were observed in T rats. The resting bradycardia after exercise training is more likely to be dependent on alterations of the pacemaker cells, inasmuch as the intrinsic HR was markedly reduced.

Carnitine supplementation and depletion: tissue carnitines and enzymes in fatty acid oxidation

Sixty-two male rats were randomly assigned into a 3 X 2 X 2 factorial design containing 12 groups according to carnitine treatment, exercise training (treadmill, 1 h, 5 times/wk, 8 wk, 26.8 m/min, 15% grade), and physical activity [rested for 60 h before they were killed or with an acute bout of exercise (1 h, 26.8 m/min, 15% grade) immediately before they were killed]. Isotonic saline was injected intraperitoneally 5 times/wk in the controls, whereas 750 mg/kg of L- or D-carnitine, respectively, were injected in the supplemented and depleted treatment groups. A significant increase in free and short-chain acyl carnitine concentration in skeletal muscle and heart was observed in L-carnitine supplemented rats, whereas a significant reduction in skeletal muscle, heart, and liver occurred in rats depleted of L-carnitine. Long-chain acyl carnitine in all tissues was not altered by carnitine treatment; training increased plasma and liver concentrations, whereas acute exercise decreased skeletal muscle and increased liver concentrations. An acute bout of exercise significantly increased short-chain acylcarnitine in liver, regardless of carnitine and/or training effects. beta-Hydroxyacyl-CoA dehydrogenase activity in skeletal muscle was induced by training but reduced by depletion. Carnitine acetyltransferase (CAT) was significantly increased in heart by L-carnitine supplementation, whereas it was reduced by depletion in skeletal muscle. Exercise training significantly increased CAT activity in skeletal muscle but not in heart, whereas acute exercise significantly increased activity in both tissues. Carnitine palmitoyltransferase activity was increased by acute exercise in the heart in only the supplemented and exercise-trained rats.