Hemodynamics and cardiac autonomic modulation after an acute concurrent exercise circuit in older individuals with pre- to established hypertension.

OBJECTIVES: Few studies have investigated whether post-exercise hypotension (PEH) after concurrent exercise (CEX) is related to changes in cardiac output (Q) and systemic vascular resistance (SVR) in older individuals. We tested whether PEH after a single bout of CEX circuits performed in open-access facilities at the Third Age Academies (TAA) in Rio de Janeiro City (Brazil) would be concomitant with decreased Q and SVR in individuals aged ≥60 years with prehypertension. Moreover, we assessed autonomic modulation as a potential mechanism underlying PEH. METHODS: Fourteen individuals (age, 65.8±0.9 y; systolic/diastolic blood pressure [SBP/DBP], 132.4±12.1/72.8±10.8 mmHg; with half of the patients taking antihypertensive medications) had their blood pressure (BP), heart rate (HR), Q, SVR, HR variability (HRV), and spontaneous baroreflex sensitivity (BRS) recorded before and 50 min after CEX (40-min circuit, including seven stations of alternate aerobic/resistance exercises at 60-70% HR reserve) and non-exercise control (CONT) sessions. The study protocol was registered in a World Health Organization-accredited office (Trial registration RBR-7BWVPJ). RESULTS: SBP (Δ=-14.2±13.1 mmHg, p=0.0001), DBP (Δ=-5.2±8.2 mmHg, p= 0.04), Q (Δ=-2.2±1.5 L/min, p=0.0001), and BRS (Δ=-3.5±2.6 ms/mmHg; p=0.05) decreased after CEX as compared with the CONT session. By contrast, the HR increased (Δ=9.4±7.2 bpm, p<0.0001), and SVR remained stable throughout the postexercise period as compared with the CONT session (Δ=0.10±0.22 AU, p=0.14). We found no significant difference between the CEX and CONT with respect to the HRV indexes reflecting autonomic modulation. CONCLUSION: CEX induced PEH in the older individuals with prehypertension status. At least in the first 50 min, PEH occurred parallel to the decreased Q and increased HR, while SVR was not different. The changes in autonomic outflow appeared to be unrelated to the acute cardiac and hemodynamic responses.

Hemodynamics and cardiac autonomic modulation after an acute concurrent exercise circuit in older individuals with pre- to established hypertension

OBJECTIVES: Few studies have investigated whether post-exercise hypotension (PEH) after concurrent exercise (CEX) is related to changes in cardiac output (Q) and systemic vascular resistance (SVR) in older individuals. We tested whether PEH after a single bout of CEX circuits performed in open-access facilities at the Third Age Academies (TAA) in Rio de Janeiro City (Brazil) would be concomitant with decreased Q and SVR in individuals aged ≥60 years with prehypertension. Moreover, we assessed autonomic modulation as a potential mechanism underlying PEH. METHODS: Fourteen individuals (age, 65.8±0.9 y; systolic/diastolic blood pressure [SBP/DBP], 132.4±12.1/72.8±10.8 mmHg; with half of the patients taking antihypertensive medications) had their blood pressure (BP), heart rate (HR), Q, SVR, HR variability (HRV), and spontaneous baroreflex sensitivity (BRS) recorded before and 50 min after CEX (40-min circuit, including seven stations of alternate aerobic/resistance exercises at 60-70% HR reserve) and non-exercise control (CONT) sessions. The study protocol was registered in a World Health Organization-accredited office (Trial registration RBR-7BWVPJ). RESULTS: SBP (Δ=−14.2±13.1 mmHg, p=0.0001), DBP (Δ=−5.2±8.2 mmHg, p= 0.04), Q (Δ=−2.2±1.5 L/min, p=0.0001), and BRS (Δ=−3.5±2.6 ms/mmHg; p=0.05) decreased after CEX as compared with the CONT session. By contrast, the HR increased (Δ=9.4±7.2 bpm, p<0.0001), and SVR remained stable throughout the postexercise period as compared with the CONT session (Δ=0.10±0.22 AU, p=0.14). We found no significant difference between the CEX and CONT with respect to the HRV indexes reflecting autonomic modulation. CONCLUSION: CEX induced PEH in the older individuals with prehypertension status. At least in the first 50 min, PEH occurred parallel to the decreased Q and increased HR, while SVR was not different. The changes in autonomic outflow appeared to be unrelated to the acute cardiac and hemodynamic responses.

Cardiac baroreflex function and vascular reactivity recovery after aerobic exercise in patients with early cirrhosis.

OBJECTIVE: To investigate the effects of aerobic exercise on the cardiac baroreflex function and vascular reactivity in patients with cirrhosis. METHODS: Thirteen patients with cirrhosis were submitted to exercise and control intervention. At baseline and at 30 and 60 min following intervention, we evaluated cardiac baroreflex sensitivity (cBRS) and the baroreflex effectiveness index (BEI) using sequence technique. Vascular reactivity was assessed inducing reactive hyperemia before and 60 min after intervention. RESULTS: At baseline, there was no difference (P interaction = 0.848) between exercise (from 3.0 ± 0.34 to 14.60 ± 1.06 ml/100ml/min) and control sessions (from 2.38 ± 0.10 to 13.73 ± 1.05 ml/100ml/min) regarding the increase in forearm blood flow during reactive hyperemia. However, this response was higher postexercise (from 3.38 ± 0.31 to 16.58 ± 1.58 ml/100ml/min) than postcontrol intervention (from 2.04 ± 0.23 to 11.98 ± 1.16 ml/100ml/min, P interaction < 0.001). BEI increased at 30- and 60-min postexercise (from 32 ± 7 to 42 ± 7 and 46 ± 7%), but not after control intervention (from 33 ± 6 to 31 ± 5 and 33 ± 7%, P interaction = 0.014). In contrast, cBRS decreased at 30-min postexercise (from 10.3 ± 1.9 to 8.2 ± 1.4 and 10.3 ± 2.1 ms/mmHg) and increased postcontrol intervention (from 7.9 ± 0.9 to 10.5 ± 1.5 and 10.3 ± 1.3 ms/mmHg, P interaction = 0.012). CONCLUSION: The results suggest that a single bout of aerobic exercise improved cardiac baroreflex function and increased vascular reactivity in patients with early-stage cirrhosis.

Effects of Inspiratory Muscle Training in Older Adults.

BACKGROUND: Inspiratory muscle training (IMT) has been widely applied to different populations, including the general population of older adults. In addition to increasing inspiratory muscle strength, other benefits of IMT in the health of this population have been reported. The primary aim of this study was to review the effects of IMT on the general parameters of health (eg, respiratory, functional, physical, and other variables) in older adults (≥ 60 y), and the secondary aim was to analyze the main IMT protocol used in the studies. METHODS: We searched the MEDLINE, PEDro, SciELO, and LILACS databases to identify relevant randomized controlled clinical trials, and we assessed their methodological quality according to the PEDro scale. The Preferred Reporting Items for Systematic review and Meta-Analysis (PRISMA) guidelines were used to guide the development of the protocol for this systematic review. RESULTS: The search yielded 7 studies involving 248 participants from 917 titles. The main outcomes investigated in response to IMT were related to the respiratory, functional, and physical variables. The results indicate that IMT promotes an increase of inspiratory muscle strength and diaphragmatic thickness in older adults. There was heterogeneity in the protocols described for this population with respect to the total training time (4-8 weeks), intensity (30-80% of the maximum inspiratory pressure), and weekly frequency (5 or 7 sessions). CONCLUSIONS: The reviewed studies revealed a positive trend for the effectiveness of IMT in improving inspiratory muscle performance in elderly subjects. More randomized studies are needed to evaluate other outcomes (eg, functional capacity, exercise capacity, cardiac autonomic control, quality of life, and others) to provide robust evidence that this training modality can promote improvements in health parameters in this population. In addition, the usual IMT prescription in this population is based on sets and repetitions, of mild to moderate intensity, performed on most days of the week, for ≥ 4 weeks.

Exercise Training Improves Heart Rate Recovery after Exercise in Hypertension

Abstract Aim: This study tested the hypothesis that: 1- the exercise training would improve the heart rate recovery (HRR) decline after maximal exercise test in hypertensive patients and; 2- the exercise training would normalize HRR decline when compared to normotensive individuals. Methods: Sixteen hypertensive patients were consecutively allocated into two groups: Exercise-trained (n = 9, 47±2 years) and untrained (n = 7, 42±3 years). An exercise-trained normotensive group (n = 11, 41±2 years) was also studied. Heart rate was evaluated by electrocardiogram. The autonomic function was evaluated based on heart rate changes on the first and the second min of recovery after the maximal exercise test. Exercise training consisted of three 60-minute exercise sessions/week for 4 months. Results: In hypertensive patients, exercise training significantly increased the HRR decline in the first (-19±2 vs. -34±3 bpm, P = 0.001) and second (-33±3 vs. -49±2 bpm, P = 0.006) minutes after the maximal exercise test. In addition, after exercise training, the initial differences in the HRR decline after exercise between hypertensive patients and normotensive individuals were no longer observed (first minute: -34±3 vs. -29±3 bpm, P = 0.52, and second minute: -49±2 vs. -47±4 bpm, P = 0.99). Conclusion: Hypertension causes a delay in HRR after the maximal exercise test yet the exercise training normalizes HRR during the post-exercise period in hypertensive patients.

Immediate and 24-h blood pressure-lowering effects of arm crank exercise in patients with traumatic lower-limb amputation: a randomized cross-over study.

AIM: This study aimed to investigate the clinic and 24-h postexercise hypotension (PEH) after a moderate-intensity arm crank exercise session in individuals with traumatic lower-limb amputation. PARTICIPANTS AND METHODS: Nine men (46±17 years) with unilateral traumatic lower-limb amputation participated in two experimental sessions conducted randomly: an aerobic exercise (EXE: arm crank ergometer, 30 min) or a control session (CON: participants remained seated on the cycle ergometer, 30 min). Clinic and 24-h systolic, diastolic, and mean blood pressure (BP) response were measured after both sessions. The clinical measurements of blood flow and forearm vascular resistance (FVR) were also performed. RESULTS: Compared with the preintervention period, the BP levels did not change in the CON session. However, EXE resulted in a significant hypotensive effect in systolic (-10±0.9 mmHg, P≤0.05), diastolic (-11±1.5 mmHg, P≤0.05), and mean BP (-11±1.2 mmHg, P≤0.05) during the entire postexercise period. The PEH was accompanied by a decreased FVR over the entire postintervention period (P≤0.05). Significant reductions were found for 24-h average systolic, diastolic, and mean BP levels (P=0.03, 0.01, and 0.02, respectively) following EXE compared with the CON session. CONCLUSION: These results showed, for the first time, that individuals with traumatic lower-limb amputation presented immediate and 24-h PEH after a single bout of arm crank exercise testing. The PEH at the clinic condition was justified, at least in part, by the reduction in peripheral FVR.

Heart rate recovery fast-to-slow phase transition: Influence of physical fitness and exercise intensity.

BACKGROUND: Postexercise heart rate (HR) recovery presents an exponential decay, with two distinct phases: a fast phase, characterized by abrupt decay of HR, and determined by parasympathetic reactivation; and a slow phase, characterized by gradual decay of HR, and predominantly determined by sympathetic withdrawal. Although several methods have been proposed to assess postexercise HR recovery, none of those methods selectively assesses the time of transition from the fast to the slow phase of the HR recovery curve (HRRPT ), and the magnitude of decay prior to (HRRFP ) and after this point (HRRSP ). Therefore, the aim of the present study was to propose a method to identify HRRPT , HRRFP , and HRRSP and to verify the effects of exercise intensity and physical fitness on such parameters. METHODS: Ten healthy young participants (24 ± 3 years; 23.6 ± 1.7 kg/m2 ) randomly underwent two exercise sessions (30 min of cycling), at moderate (MI) and high intensity (HI); followed by 5 min of inactive recovery. HR was continuously recorded during the sessions. The algorithm for HRRPT analysis was written in Python and is freely available online. RESULTS: HRRPT and HRRSP were increased in HI session compared with MI (81 ± 24 vs. 60 ± 20 s; 8 ± 10 vs. 1 ± 5 bpm; p = .04), and there was no difference in HRRFP between sessions (49 ± 15 vs. 46 ± 10 bpm; p = .17). In addition, HRRPT for MI exercise session was significantly and negatively associated with VO2max (r = -0.85, p < .05). CONCLUSION: The method herein presented was sensitive to exercise intensity, and partially responsive to aerobic fitness. Next studies should perform the pharmacological and clinical validations of the method.

Increased peripheral vascular resistance in male patients with traumatic lower limb amputation: one piece of the cardiovascular risk puzzle.

AIM: The increased morbidity and mortality in traumatic lower limb amputees can be explained by the development of risk factors, among which high blood pressure plays an important role. However, the possible mechanisms underlying increased blood pressure levels observed in this population remain unclear. Thus, we aimed to test the hypothesis that peripheral vascular resistance is increased at rest in patients with traumatic lower limb amputation. PATIENTS AND METHODS: In a cross-sectional study, eight patients with traumatic unilateral lower limb amputation (amputee group) and eight healthy individuals without amputation (control group) were included. Resting blood pressure, heart rate, and forearm blood flow were recorded simultaneously and thus, forearm vascular resistance was calculated. RESULTS: The amputee group showed higher systolic (126±2 vs. 118±5 mmHg, P<0.01), diastolic (78±2 vs. 63±3 mmHg, P<0.01), mean blood pressure (94±2 vs. 81±3 mmHg, P<0.01), and heart rate (74±5 vs. 65±8 bpm, P=0.02) compared with the control group. Despite the similar forearm blood flow response between groups, patients with traumatic lower limb amputation presented increased peripheral vascular resistance at rest compared with the control group (31.3±3.8 vs. 25.7±6.5 U, P=0.05). CONCLUSION: Patients with traumatic amputation present increased peripheral vascular resistance. Our findings clarify one possible mechanism underlying the higher blood pressure levels observed in this population.

Effects of load and type of physical training on resting and postexercise cardiac autonomic control.

The aim of the study was to investigate the influence of training load and exercise mode on heart rate variability and heart rate recovery (HRR) in healthy individuals. The subjects were divided into three groups: sedentary (SED), resistance trained (RT) and aerobically trained (RT). Resting and postmaximal exercise RR intervals were recorded on supine and seated position, respectively. The HRV indices calculated in the resting position were RMSSD and LF and HF power densities. The following HRR indices were calculated throughout the 5-minute postmaximal recovery period: semi-logarithmic regression analysis of the first 30 s (T30); absolute difference between the peak and 60 s HR (HRR(60s)); and mono-exponential time constant of HRR (HRRτ). The RMSSD on subsequent 30-s segments (RMSSD(30s)) on recovery period was also calculated. Both RT and AT groups presented faster HRR than SED (P<0·05). The aerobic trained group was the only group that presented vagal reactivation, when analysing the RMSSD(30s). There were no correlations between the Baecke sport score and the HRV vagal-related indices. However, it was significantly correlated with HRR. It was concluded that that the training load positively influences the HRR, but has no effect on the HRV at rest and that the type of exercise, showed a marked influence on HRV recovery.

Effects of cardiac resynchronization therapy on muscle sympathetic nerve activity.

INTRODUCTION: Muscle sympathetic nerve activity (MSNA) is an independent prognostic marker in patients with heart failure (HF). Therefore, its relevance to the treatment of HF patients is unquestionable. OBJECTIVES: In this study, we investigated the effects of cardiac resynchronization therapy (CRT) on MSNA response at rest and during exercise in patients with advanced HF. METHODS: We assessed 11 HF patients (51 ± 3.4 years; New York Heart Association class III-IV; left ventricular ejection fraction 27.8 ± 2.2%; optimal medical therapy) submitted to CRT. Evaluations were made prior to and 3 months after CRT. MSNA was performed at rest and during moderate static exercise (handgrip). Peak oxygen consumption (VO2 ) was evaluated by means of cardiopulmonary exercise test. HF patients with advanced NYHA class without CRT and healthy individuals were also studied. RESULTS: CRT reduced MSNA at rest (48.9 ± 11.1 bursts/min vs 33.7 ± 15.3 bursts/min, P < 0.05) and during handgrip exercise (MSNA 62.3 ± 13.1 bursts/min vs 46.9 ± 14.3 bursts/min, P < 0.05). Among HF patients submitted to CRT, the peak VO2 increased (12.9 ± 2.8 mL/kg/min vs 16.5 ± 3.9 mL/kg/min, P < 0.05) and an inverse correlation between peak VO2 and resting MSNA (r = -0.74, P = 0.01) was observed. CONCLUSIONS: In patients with advanced HF and severe systolic dysfunction: (1) a significant reduction of MSNA (at rest and during handgrip) occurred after CRT, and this behavior was significantly superior to HF patients receiving only medical therapy; (2) MSNA reduction after CRT had an inverse correlation with O2 consumption outcomes.

Influência do nível de atividades físicas laborais, de lazer e locomoção na modulação autonômica cardíaca de repouso e na frequência cardíaca de recuperação / Influence of labor, leisure and locomotion physical activity level on resting cardiac autonomic modulation and in heart rate recovery

O objetivo deste estudo foi verificar a influência do nível das atividades laborais, de lazer e locomoção na modulação autonômica cardíaca de repouso e na freqüência cardíaca de recuperação. Métodos: Vinte jovens, saudáveis, do sexo masculino, que não praticavam exercício físico regular, foram divididos em dois grupos de acordo com o nível de atividade física habitual, obtido a partir do cálculo do escore total (ET), do questionário de Baecke: ‘menos ativos’ (n=10; 22,8±1,9 anos) e ‘mais ativos’ (n=10; 22,3±2,2 anos). Os registros dos intervalos R-R dos voluntários foram feitos em repouso, na posição supina por 15 minutos; durante o teste cardiopulmonar máximo e; por 5 minutos do período de recuperação. A variabilidade da freqüência cardíaca (VFC) foi analisada no domínio do tempo e da freqüência durante os últimos 5 minutos da coleta de repouso. Analisaram-se também índices de recuperação da freqüência cardíaca (FCrec). Resultados: Não houve diferença significativa entre os dois grupos em nenhum dos índices da VFC, assim como nos índices da FCrec. Conclusão: sugere-se que apenas atividades laborais, de lazer e te locomoção parecem não promover efeitos significativos na modulação autonômica cardíaca de repouso e na freqüência cardíaca de recuperação em jovens saudáveis. Nesse sentido, reforça-se a necessidade de atividades físicas sistematizadas e/ou aumento na intensidade das atividades laborais, de lazer e locomoção para promover adaptações autonômicas cardíacas.

Objective: The aim of this study was to investigate the labour, leisure and locomotion physical activities level on resting cardiac autonomic modulation and in heart rate recovery (HRR). Methods: 20 young healthy men, that didn’t practice physical exercise regularly, were divided into twogroups, according to their habitual physical activity level, obtained by the calculation of the total score, from Baecke’s questionnaire: ‘less actives’ (n=10; 22,8±1,9 years) and ‘more actives’ (n=10; 22,3±2,2years). The subjects’ R-R interval register was done by the supine resting position for 15 minutes; during the maximal effort text and; for 5 minutes from the recovery period. The heart rate variability (HRV) was analyzed in time and frequency domains, during the last 5 minutes of the resting register. It was alsoanalyzed HRR indexes. Results: There aren’t significant differences between the two groups in none of the HRV nor in the HRR indexes. Conclusion: In summary, it is suggested that only labour, leisure and locomotion activities seem not to provide significant effects on the resting cardiac autonomic modulation likewise in the HRR in healhy young men. Therefore, systematized physical activity or the rising of the intensity of labour, leisure and locomotionis are reinforced to provide positive cardiac autonomic adaptations.

Dieta hiperlipídica e ácido linoleico conjugado: efeitos nos lipídios séricos, peso e composição corporal de camundongos Apo E(-/-) exercitados / High-fat diet and conjugated linoleic acid: effects on serun lipids, weight and body composition of exercised Apo E(-/-) mice

Estratégias têm sido utilizadas para a prevenção de doenças cardiovasculares e aumento de peso. Sendo assim, muito tem sido especulado sobre alimentos funcionais e seus efeitos benéficos para a saúde humana e, em especial do Ácido Linoleico Conjugado (CLA). O objetivo foi avaliar os efeitos da dieta hiperlipídica e do CLA sobre os lipídios séricos, peso e composição corporal de camundongos Apolipoproteina E(-/-) (Apo E) exercitados. Camundongos knockout para Apo E foram alocados em quatro grupos/dieta: Normal (n=5), Hiperlipídica (n=6), Normal+CLA (n=5) e Hiperlipídica+CLA (n=6). Todos os grupos foram submetidos a um protocolo de corrida em esteira. Determinou-se o colesterol total, LDL-c e HDL-c no sangue, o peso e a composição corporal. Utilizou-se ANOVA e Tukey ao nível de significância de 5%. A dieta hiperlipídica elevou o colesterol total (Hiperlipídica=920,2±392,3 e Normal=382,3±207,9), LDL-c (Hiperlipídica=893,9±402,9 e Normal=339,9±204,8) e o peso corporal (Hiperlipídica=25,83±1,90 e Normal=339,9±204,8). O CLA reduziu a gordura (CLA=4,24±1,82 e Sem CLA=6,28±2,77) e elevou a proteína (CLA=23,02±1,04 e Sem CLA=21,45±1,04) na carcaça. Concluiu-se que a dieta hiperlipídica aumenta colesterol total e LDL-c e, o consumo de CLA diminui o gordura e aumenta a proteína na carcaça de camundongos Apo E(-/-) exercitados.

Strategies have been used for prevention of cardiovascular disease and weight gain. So much has been talked about functional foods and their beneficial effects on human health and, in particular conjugated linoleic acid. Evaluate the effects of high-fat diet and CLA on serum lipids, weight and body composition in Apolipoprotein E (-/-) mice (Apo E) exercised. Knockout mice ApoE were divided into four groups/diet: Normal (n=5), High-fat (n = 6), Normal+CLA (n=5) and High-fat+CLA (n=6). All groups underwent a protocol of treadmill running. Total cholesterol, LDL-c and HDL-c in the serum, weight and body composition were measured ANOVA followed by Tukey test were used (P<0.05). The high-fat diet elevated total cholesterol (High-fat=920,2± 392,3 and Normal=382,3±207,9), LDL-c (High fat=893,9±402,9 and Normal=339,9±204,8) and body weight (High-fat=25,83±1,90 and Normal= 339,9±204,8). The CLA reduced fat (CLA=4,24±1,82 and Without CLA=6,28±2,77) and increased the protein (CLA=23,02±1,04 and Without CLA=21,45±1,04) in the carcass. We conclude that the High-fat diet increases total cholesterol and LDL-C, and the consumption of the CLA reduces fat and increases the protein in the body composition of exercised ApoE(-/-) mice.

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 VO(2) 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.

A high-fat meal impairs muscle vasodilatation response to mental stress in humans with Glu27 beta2-adrenoceptor polymorphism.

BACKGROUND: Forearm blood flow responses during mental stress are greater in individuals homozygous for the Glu27 allele. A high-fat meal is associated with impaired endothelium-dependent dilatation. We investigated the impact of high-fat ingestion on the muscle vasodilatory responses during mental stress in individuals with the Glu27 allele and those with the Gln27 allele of the beta2-adrenoceptor gene. METHODS: A total of 162 preselected individuals were genotyped for the Glu27Gln beta2-adrenoceptor polymorphism. Twenty-four individuals participated in the study. Fourteen were homozygous for the Gln27 allele (Gln27Gln, 40 +/- 2 years; 64 +/- 2 kg), and 10 were homozygous for the Glu27 allele (Glu27Glu, 40 +/- 3 years; 65 +/- 3 kg). Forearm blood flow was evaluated by venous occlusion plethysmography before and after ingestion of 62 g of fat. RESULTS: The high-fat meal caused no changes in baseline forearm vascular conductance (FVC, 2.2 +/- 0.1 vs. 2.4 +/- 0.2; P = 0.27, respectively), but reduced FVC responses to mental stress (1.5 +/- 0.2 vs. 0.8 +/- 0.2 units; P = 0.04). When volunteers were divided according to their genotypes, baseline FVC was not different between groups (Glu27Glu = 2.4 +/- 0.1 vs. Gln27Gln = 2.1 +/- 0.1 units; P = 0.08), but it was significantly greater in Glu27Glu individuals during mental stress (1.9 +/- 0.4 vs. 1.0 +/- 0.3 units; P = 0.04). High-fat intake eliminated the difference in FVC responses between Glu27Glu and Gln27Gln individuals (FVC, 1.3 +/- 0.4 vs. 1.2 +/- 0.4; P = 0.66, respectively). CONCLUSION: These findings demonstrate that a high-fat meal impairs muscle vasodilatation responses to mental stress in humans. However, this reduction can be attributed to the presence of the homozygous Glu27 allele of the beta2-adrenoceptor gene.

Exercise training restores baroreflex sensitivity in never-treated hypertensive patients.

The effects of exercise training on baroreflex control of sympathetic nerve activity in human hypertension are unknown. We hypothesized that exercise training would improve baroreflex control of muscle sympathetic nerve activity (MSNA) and heart rate (HR) in patients with hypertension and that exercise training would reduce MSNA and blood pressure (BP) in hypertensive patients. Twenty never-treated hypertensive patients were randomly divided into 2 groups: exercise-trained (n=11; age: 46+/-2 years) and untrained (n=9; age: 42+/-2 years) patients. An age-matched normotensive exercise-trained group (n=12; age: 42+/-2 years) was also studied. Baroreflex control of MSNA (microneurography) and HR (ECG) was assessed by stepwise intravenous infusions of phenylephrine and sodium nitroprusside and analyzed by linear regression. BP was monitored on a beat-to-beat basis. Exercise training consisted of three 60-minute exercise sessions per week for 4 months. Under baseline conditions (before training), BP and MSNA were similar between hypertensive groups but significantly increased when compared with the normotensive group. Baroreflex control of MSNA and HR was similar between hypertensive groups but significantly decreased when compared with the normotensive group. In hypertensive patients, exercise training significantly reduced BP (P<0.01) and MSNA (P<0.01) levels and significantly increased baroreflex control of MSNA and HR during increases (P<0.01 and P<0.03, respectively) and decreases (P<0.01 and P<0.03, respectively) in BP. The baseline (preintervention) difference in baroreflex sensitivity between hypertensive patients and normotensive individuals was no longer observed after exercise training. No significant changes were found in untrained hypertensive patients. In conclusion, exercise training restores the baroreflex control of MSNA and HR in hypertensive patients. In addition, exercise training normalizes MSNA and decreases BP levels in these patients.

Blunted muscle vasodilatation during chemoreceptor stimulation in patients with heart failure.

Chemoreflex control of sympathetic nerve activity is exaggerated in heart failure (HF) patients. However, the vascular implications of the augmented sympathetic activity during chemoreceptor activation in patients with HF are unknown. We tested the hypothesis that the muscle blood flow responses during peripheral and central chemoreflex stimulation would be blunted in patients with HF. Sixteen patients with HF (49 +/- 3 years old, Functional Class II-III, New York Heart Association) and 11 age-paired normal controls were studied. The peripheral chemoreflex control was evaluated by inhalation of 10% O(2) and 90% N(2) for 3 min. The central chemoreflex control was evaluated by inhalation of 7% CO(2) and 93% O(2) for 3 min. Muscle sympathetic nerve activity (MSNA) was directly evaluated by microneurography. Forearm blood flow was evaluated by venous occlusion plethysmography. Baseline MSNA were significantly greater in HF patients (33 +/- 3 vs. 20 +/- 2 bursts/min, P = 0.001). Forearm vascular conductance (FVC) was not different between the groups. During hypoxia, the increase in MSNA was significantly greater in HF patients than in normal controls (9.0 +/- 1.6 vs. 0.8 +/- 2.0 bursts/min, P = 0.001). The increase in FVC was significantly lower in HF patients (0.00 +/- 0.10 vs. 0.76 +/- 0.25 units, P = 0.001). During hypercapnia, MSNA responses were significantly greater in HF patients than in normal controls (13.9 +/- 3.2 vs. 2.1 +/- 1.9 bursts/min, P = 0.001). FVC responses were significantly lower in HF patients (-0.29 +/- 0.10 vs. 0.37 +/- 0.18 units, P = 0.001). In conclusion, muscle vasodilatation during peripheral and central chemoreceptor stimulation is blunted in HF patients. This vascular response seems to be explained, at least in part, by the exaggerated MSNA responses during hypoxia and hypercapnia.

Abnormal muscle metaboreflex control of sympathetic activity in never-treated hypertensive subjects.

BACKGROUND: Muscle metaboreflex control in hypertensive subjects has not been described yet. We investigated the integrity of muscle metaboreflex control of muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in never-treated hypertensive subjects. METHODS: Eighteen hypertensive (42+/-1 years) and 22 normotensive subjects (38+/-1 years) were studied. The MSNA was measured by microneurography and forearm blood flow (FBF) by venous occlusion plethysmography. The BP was noninvasively monitored. RESULTS: Baseline MSNA was significantly increased in hypertensive subjects when compared with normal subjects (34+/-2 v 22+/-2 bursts/min, P<.001). Baseline FBF was significantly decreased in hypertensive subjects (2.66+/-0.2 v 2.05+/-0.1 mL/min/100 mL, P=.04). During moderate handgrip exercise (30% maximal voluntary contraction), MSNA levels were significantly higher in hypertensive subjects. However, MSNA responses were significantly lower in hypertensive subjects (1+/-3 v 10+/-2 bursts/100 heart beats, P = .001). Similarly, FBF responses were significantly lower in hypertensive subjects when compared with normotensive subjects (0.70+/-0.19 v 1.60+/-0.36 mL/min/100 mL, P=.04). During the postexercise circulatory arrest, when the metaboreflex control is isolated, MSNA levels returned toward baseline in hypertensive subjects (58+/-4 v 55+/-3 bursts/100 heart beats, P=.98). In contrast, in normotensive subjects, MSNA levels remained significantly elevated when compared with baseline (48+/-3 v 35+/-1 bursts/100 heart beats, P<.001). CONCLUSIONS: These findings suggest an association between hypertension and decreased muscle metaboreflex control of MSNA.

Gly16 + Glu27 beta2-adrenoceptor polymorphisms cause increased forearm blood flow responses to mental stress and handgrip in humans.

We hypothesized that the muscle vasodilatation during mental stress and exercise would vary among humans who are polymorphic at alleles 16 and 27 of the beta(2)-adrenoceptors. From 216 preselected volunteers, we studied 64 healthy, middle-aged normotensive women selected to represent three genotypes: homozygous for the alleles Arg(16) and Gln(27) (Arg(16)/Gln(27), n = 34), Gly(16) and Gln(27) (Gly(16)/Gln(27), n = 20), and Gly(16) and Glu(27) (Gly(16)/Glu(27), n = 10). Forearm blood flow (plethysmography) and muscle sympathetic nerve activity (microneurography) were recorded during 3-min Stroop color-word test and 3-min handgrip isometric exercise (30% maximal voluntary contraction). Baseline muscle sympathetic nerve activity, forearm vascular conductance, mean blood pressure, and heart rate were not different among groups. During mental stress, the peak forearm vascular conductance responses were greater in Gly(16)/Glu(27) group than in Gly(16)/Gln(27) and Arg(16)/Gln(27) groups (1.79 +/- 0.66 vs. 0.70 +/- 0.11 and 0.58 +/- 0.12 units, P = 0.03). Similar results were found during exercise (0.80 +/- 0.25 vs. 0.28 +/- 0.08 and 0.31 +/- 0.08 units, P = 0.02). Further analysis in a subset of subjects showed that brachial intra-arterial propranolol infusion abolished the difference in vasodilatory response between Gly(16)/Glu(27) (n = 6) and Arg(16)/Gln(27) (n = 7) groups during mental stress (0.33 +/- 0.20 vs. 0.46 +/- 0.21 units, P = 0.50) and exercise (0.08 +/- 0.06 vs. 0.03 +/- 0.03 units, P = 0.21). Plasma epinephrine concentration in Arg(16)/Gln(27) and Gly(16)/Glu(27) groups was similar. In conclusion, women who are homozygous for Gly(16)/Glu(27) of the beta(2)-adrenoceptors have augmented muscle vasodilatory responsiveness to mental stress and exercise.