Effects of l-arginine supplementation associated with continuous or interval aerobic training on chronic heart failure rats.

OBJECTIVE: Chronic heart failure (CHF) is related with exercise intolerance and impaired nitric oxide (NO) production, which can lead to several functional capacity alterations. Considering the possible superiority of aerobic interval training compared to continuous training and the capacity of l-arginine to restore the NO pathway, the aim of the present study was to investigate whether these treatments are beneficial to exercise capacity, muscle mass preservation and hemodynamic, inflammatory and oxidative stress parameters in CHF rats. METHODS: Thirty-eight male Wistar rats post 6weeks of myocardial infarction (MI) surgery were randomly assigned into 6 CHF groups: sedentary (SED, n=6); SED+Arg (n=7); ACT (n=8); ACT+Arg (n=5); AIT (n=7); AIT+Arg (n=5). Exercise test capacity (ETC) was performed pre and post 8weeks of intervention. Supplemented rats received Arg (1g/kg) by oral gavage (7×/week). Exercise training was performed on a rat treadmill (5×/week). Hemodynamic variables, tissue collection, congestion, inflammatory cytokines, and oxidative parameters were evaluated at the end of protocols. RESULTS: All trained groups showed a superior exercise capacity compared to SED groups on the post-intervention test (p<0.0001). Pulmonary congestion was attenuated in AIT and AIT+Arg compared with the SED group (p<0.05). Left ventricular end-diastolic pressure (LVEDP) was lower in ACT+Arg, AIT, and AIT+Arg groups than SED group (p<0.05). Association of AIT with Arg supplementation was able to improve hemodynamic responses (left ventricular systolic pressure (LVSP), systolic blood pressure (SBP), +dP/dtmax, and -dP/dtmax (p<0.05), likewise, decrease muscular and renal lipid peroxidation and tumor necrosis factor (TNF)-α, and increase interleukin (IL)-10/TNF-α plasmatic levels (p<0.01). Groups that associated aerobic exercise with Arg supplementation (ACT+Arg and AIT+Arg) revealed higher gastrocnemius mass compared to the SED group (p<0.01). CONCLUSIONS: Both aerobic training protocols were capable to improve aerobic capacity, and the association with Arg supplementation was important to attenuate muscle loss. Moreover, interval training associated with Arg supplementation elicits greater improvements in hemodynamic parameters, contributing to reduction in pulmonary congestion, and demonstrated particular responses in the inflammatory profile and in the antioxidant status.

Maximal oxygen uptake and exercise tolerance are improved in rats with heart failure subjected to low-level laser therapy associated with resistance training.

Exercise tolerance and maximal oxygen uptake (VO2max) are reduced in heart failure (HF). The influence of combined resistance training (RT) and low-level laser therapy (LLLT) on exercise tolerance and VO2max in HF has not yet been explored. The aim of this study was to evaluate the influence of combined RT and LLLT on VO2max and exercise tolerance in rats with HF induced by myocardial infarction (MI). Rats were allocated to sedentary sham (Sed-Sham, n = 12), sedentary heart failure (Sed-HF, n = 9), RT heart failure (RT-HF, n = 7) and RT associated with LLLT heart failure (RT + LLLT-HF, n = 7) groups. After MI or sham surgery, rats underwent a RT and LLLT protocol (applied immediately after RT) for 8 weeks. VO2max and exercise tolerance were evaluated at the end of protocol. HF rats subjected to LLLT combined with RT showed higher VO2basal (41 %), VO2max (40 %), VO2reserve (39 %), run distance (46 %), time to exhaustion (30 %) and maximal velocity (22 %) compared with HF rats that underwent RT alone. LLLT associated with RT improved oxygen uptake and exercise tolerance compared with RT alone in HF rats.

Light-emitting diode therapy (LEDT) improves functional capacity in rats with heart failure.

The syndrome of heart failure (HF) promotes central and peripheral dysfunctions that result in functional capacity decrease, leading to fatigue, dyspnea, and exercise intolerance. The use of light-emitting diode therapy (LEDT) has shown good results reducing fatigue and exercise intolerance, when applied on skeletal muscles before or after exercises. Thereby, the aim of this study was to compare the effects of LEDT on functional capacity, aerobic power, and hemodynamic function in HF rats. Male Wistar rats (230-260 g) were randomly allocated into three experimental groups: Sham (n = 6), Control-HF (n = 4), and LEDT-HF (n = 6). The animals were subjected to an exercise performance test (ET) with gas analysis coupled in a metabolic chamber for rats performed two times (6 and 14 weeks after myocardial infarction). On the day after the baseline aerobic capacity test, the animals were submitted during 8 weeks to the phototherapy protocol, five times/week, 60 s of irradiation, 6 J delivered per muscle group. Statistical analysis was performed by one- and two-way ANOVAs with repeated measures and Student-Newman-Keuls post hoc tests (p ≤ 0.05). Comparing the percentage difference (Δ) between baseline and the final ET, there was no significant difference for the VO2max variable considering all groups. However, Sham and LEDT-HF groups showed higher relative values than the Control-HF group, respectively, for distance covered (27.7 and 32.5 %), time of exercise test (17.7 and 20.5 %), and speed (13.6 and 12.2 %). In conclusion, LEDT was able to increase the functional capacity evaluated by distance covered, time, and speed of exercise in rats with HF.

Skeletal muscle electrical stimulation improves baroreflex sensitivity and heart rate variability in heart failure rats.

The goal of the current study was to evaluate the effects of electrical stimulation (ES) on the arterial baroreflex sensitivity (BRS) and cardiovascular autonomic control in rats with chronic heart failure (CHF). Male Wistar rats were designated to one of four groups: placebo sham (P-Sham, n=9), ES sham (ES-Sham, n=9), placebo CHF (P-CHF, n=9) or ES CHF (ES-CHF, n=9). The ES was adjusted at a low frequency (30 Hz), duration of 250 µs, with hold and rest time of 8s (4 weeks, 30 min/day, 5 times/week). It was applied on the gastrocnemius muscle with intensity to produce a visible muscle contraction. The rats assigned to the placebo groups performed the same procedures with the equipment turned off. The two-way ANOVA and the post hoc Student-Newman-Keuls tests (P<0.05) were used to data comparison. The BRS was higher in ES-Sham group compared to the P-Sham group and the ES-CHF group compared to the P-CHF group. ES was able to decrease heart rate sympatho-vagal modulation and peripheral sympathetic modulation in ES-CHF compared to P-CHF group. Interestingly, heart rate sympatho-vagal modulation was similar between ES-CHF and P-Sham groups. Thus, ES enhances heart rate parasympathetic modulation on heart failure (ES-CHF) compared to placebo (P-CHF), with consequent decrease of sympatho-vagal balance in the ES-CHF group compared to the P-CHF. The results show that a 4 week ES protocol in CHF rats enhances arterial BRS and cardiovascular autonomic control.

Qualidade de vida e capacidade funcional de idosos adscritos em um PSF da cidade de Cruz Alta/RS / Quality of life and functional capacity of elderly people enrolled in a family health program in Cruz Alta/RS

O objetivo deste estudo foi comparar a qualidade de vida entre idosos autônomos e dependentes vinculados ao PSF de um bairro da cidade de Cruz Alta/RS e identificar a existência de associação entre a idade, o gênero e a avaliação subjetiva de saúde com a capacidade funcional. Foram avaliados 103 idosos com idade média de 70,8 anos (73 por cento mulheres e 27 por cento homens). Os instrumentos usados para avaliação da capacidade funcional foram o índice de Barthel e a escala de Lawton e para avaliação da qualidade de vida, o WHOQOL-bref. A associação entre as variáveis foi estimada através do coeficiente de correlação de Pearson e através do teste do qui-quadrado. As diferenças eventuais entre as médias dos sujeitos foram estimadas através do teste t de Student. Na determinação da capacidade funcional, foram classificados 65 idosos como autônomos e 38 como dependentes. Não foi identificada associação entre a capacidade funcional e o gênero (p = 0,16). Porém houve associação entre a capacidade funcional e a idade (p = 0,000) e a avaliação subjetiva de saúde (p = 0,007). Na comparação das médias dos domínios do WHOQOL-bref entre o grupo autônomo e dependente, foi encontrada diferença significativa em todos os domínios e na qualidade de vida global. Ao final, os resultados indicaram que nos idosos que referiram uma pior avaliação subjetiva da condição da saúde há também maior dependência.

The aim of this study was to compare the quality of life among autonomous and dependent elderly people enrolled in a Family Health Program (FHP) in a district of Cruz Alta, Rio Grande do Sul, Brazil and to identify the existence of an association among age, gender and health subjective evaluation with functional capacity. One hundred and three elderly people averaging 70.8 years old (73 percent female and 27 percent male) were evaluated. The instruments used to evaluate the physical capacity were the Barthel index and Lawton’s Scale, and WHOQOL-bref to evaluate quality of life. Association among the variables was estimated through the Pearson correlation coefficient and through the chi-square test. Eventual differences among the averages of the subjects were estimated through the t Student test. In order to determine the functional capacity, 65 elderly were classified as autonomous and 38 as dependent. It was not identified association between functional capacity and gender (p = 0.16), but there was an association between functional capacity and age (p = 0.000) and the subjective health evaluation (p = 0.007). When comparing the WHOQOL-bref dominion averages between autonomous and dependent groups, a significant difference was found in all dominions and in global quality of life. In conclusion, results indicated that in those elderly people who referred a worse health condition in the subjective evaluation, the dependence is greater.