Aerobic Swim Training Restores Aortic Endothelial Function by Decreasing Superoxide Levels in Spontaneously Hypertensive Rats

OBJECTIVE: We aimed to determine whether aerobic training decreases superoxide levels, increases nitric oxide levels, and improves endothelium-dependent vasodilation in the aortas of spontaneously hypertensive rats. METHODS: Spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) were distributed into 2 groups: sedentary (SHRsd and WKYsd, n=10 each) and swimming-trained (SHRtr, n=10 and WKYtr, n=10, respectively). The trained group participated in training sessions 5 days/week for 1 h/day with an additional work load of 4% of the animal’s body weight. After a 10-week sedentary or aerobic training period, the rats were euthanized. The thoracic aortas were removed to evaluate the vasodilator response to acetylcholine (10-10 to 10-4 M) with or without preincubation with L-NG-nitro-L-arginine methyl ester hydrochloride (L-NAME; 10-4 M) in vitro. The aortic tissue was also used to assess the levels of the endothelial nitric oxide synthase and nicotinamide adenine dinucleotide oxidase subunit isoforms 1 and 4 proteins, as well as the superoxide and nitrite contents. Blood pressure was measured using a computerized tail-cuff system. RESULTS: Aerobic training significantly increased the acetylcholine-induced maximum vasodilation observed in the SHRtr group compared with the SHRsd group (85.9±4.3 vs. 71.6±5.2%). Additionally, in the SHRtr group, superoxide levels were significantly decreased, nitric oxide bioavailability was improved, and the levels of the nicotinamide adenine dinucleotide oxidase subunit isoform 4 protein were decreased compared to the SHRsd group. Moreover, after training, the blood pressure of the SHRtr group decreased compared to the SHRsd group. Exercise training had no effect on the blood pressure of the WKYtr group. CONCLUSIONS: In SHR, aerobic swim training decreased vascular superoxide generation by nicotinamide adenine dinucleotide oxidase subunit isoform 4 and increased nitric oxide bioavailability, thereby improving endothelial function

Efeitos do treinamento físico aeróbio sobre a bioatividade do óxido nítrico e a vasodilatação aórtica

Aerobic training (AT) is an important way to improve endothelial function. However, it is not completely understood how the blood vessels adapt themselves to the AT. Therefore, the aim of this study was to investigate exercise training-induced adaptations on the nitric oxide (NO) production, antioxidant defense and aorta vasodilatation in normotensive rats. The rats were subjected to an AT protocol (treadmill, ~55% Max Veloc., 5 bouts/week, 60 min/bout, 11 wks). After the AT, it was examined in vitro vasomotor function to acetylcholine (ACh) and sodium nitroprusside (SNP), and biochemical analysis in the aorta. Aerobic training significantly increased (P < 0.05) by 62% the expression of the endothelial nitric oxide synthase (eNOS). However, ET did not modify the relaxation response and sensitivity to ACh. In contrast, AT significantly reduced aortic sensitivity to SNP (-8.26 ± 0.081 vs. -7.79 ± 0.099 Log [M], Sed vs. AT, respectively, P < 0.001). These results demonstrate that aerobic AT was able to modify one important mechanism related to the NO bioactivity, which is the increase of eNOS expression. However, this response did not contribute to improve of the aortic vasodilatation response to acetylcholine and decreased the sensitivity to SNP.O treinamento físico aeróbio (TF) é um importante meio para melhorar a função endotelial. Entretanto, como os vasos se adaptam ao TF ainda não está completamente esclarecido. Desta forma, o presente estudo teve por objetivo investigar, em ratos normotensos, os efeitos do TF sobre a via de produção de óxido nítrico (NO) e a defesa antioxidante vascular, e suas conseqüências sobre a resposta vasodilatadora em aorta isolada. Os ratos foram submetidos a um protocolo de TF aeróbio (esteira rolante, ~55% Veloc.Máx; cinco sessões/sem., 60 min/sessão, período de 11 semanas). Após o TF, foi avaliada a função vasomotora "in vitro" pela curva de concentração-efeito à acetilcolina (ACh) e ao nitroprussiato de sódio (NPS), e realizadas medidas bioquímicas na aorta. O programa de TF aumentou significativamente (P < 0,05) em 62% a expressão da enzima óxido nítrico sintase endotelial (eNOS). Entretanto, o TF não modificou significativamente a expressão e atividade da enzima antioxidante superóxido dismutase. Além disso, o TF não modificou o relaxamento individual e a sensibilidade à ACh. Por outro lado, o TF diminuiu significativamente a sensibilidade ao NPS (-8,26 ± 0,081 vs. -7,79 ± 0,099 Log [M], S vs T, respectivamente, P < 0,001). Os resultados apresentados demonstram que o TF aeróbio foi capaz de alterar um dos mecanismos envolvidos na bioatividade do NO, marcadamente o aumento da expressão da eNOS. Entretanto, esta modificação não levou à melhora da responsividade vasodilatadora aórtica estimulada pela acetilcolina e provocou menor sensibilidade ao NPS

Effect of physical training and impact of glucose ingestion 30 minutes before prolonged exercise in insulin-dependent diabetic subjects

O presente estudo teve por objetivo verificar o efeito do treinamento físico (TF) sobre o impacto metabólico da ingestão de glicose (GL) pré-exercício na inter-relação hormônio substrato durante o exercício prolongado. Foram estudados sete indivíduos controle (C) e seis diabéticos (D) nas fases de pré e de p6s-TF. O teste de tolerância ao exercício (TTE) até a exaustão (64 ± 5% do VO2 máx) foi realizado 30 minutos apos a ingestão de placebo e GL. A ingestão de GL pré-exercício aumentou a tolerância ao exercício nas fases de pré e de p6sTF. Nos grupos C e D, o TF não modificou o impacto da ingestão de GL pré-exercício nas concentrações de GL, acido lático, epinefrina (EP), cortisol (CORT), insulina, peptídeo-C, glucagon (GLUC) e hormônio de crescimento (HC), mas antecipou a elevação da concentração de AGL no grupo C. O TF não modificou a maior concentração de GL no grupo D durante todo o período experimental. Em conclusão; 1- A ingestão de GL pré-exercício aumenta a tolerância ao exercício nos grupos C e D, tanto na fase de pré como na fase de pós-TF, 2- No grupo D, o TF não modifica o efeito agudo do exercício, qual seja, de apenas atenuar a hiperglicemia causada pela ingestão de GL pré-exercício, 3- No grupo C, o TF diminui a ação inibitória da ingestão de GL pré-exercício nas concentrações de AGL e 4- O TF não modifica a ação inibitória da ingestão de GL pré-exercício nas concentrações de EP, CORT, GLUC e HC nos grupos C e DThe aim of the present investigation was to verify the effect of exercise training (ET) on the impact of glucose (GL) ingestion before exercise to exhaustion on the substrate hormone interplay in insulin-dependent diabetic subjects. Seven healthy control subjects (C) and six diabetic patients (D) were studied before and after ET. The exercise tolerance test (ETT) until exhaustion (64 ± 5% of V02max) was performed after oral ingestion of GL or placebo solution given 30 minutes prior to exercise. GL ingestion prior to exercise increased exercise tolerance both before and after ET. In C and D, groups ET did not significantly modify the effect of GL ingestion prior to exercise on GL, lactic acid, epinephrine (EP), cortisol (CORT), insulin, C-peptide, glucagon (GLUC), and growth hormone (GH) concentrations, but the exercise-induced enhancement in FFA occured at 60 min. of exercise rather than at exhaustion. ET had no effect on the elevated blood glucose concentration in the D group during all experimental periods. Conclusion: 1- in the C and D groups, glucose ingestion pre-exercise increases exercise tolerance both before and after ET; 2- In the D group, ET did not change the acute effect of exercise, that is, only attenuating hyperglycemia provoked by GL ingestion; 3- In the C group, ET decreases the inhibitory effect of glucose ingestion on FFA concentration, and 4- ET, in the C and D groups, did not change the diminishment of EP, CORT, GLUC, and GH provoked by glucose ingestio

Moderate exercise training decreases aortic superoxide production in myocardial infarcted rats

Myocardial infarction (MI) has been associated with increases in reactive oxygen species (ROS). Exercise training (ET) has been shown to exert positive modulations on vascular function and the purpose of the present study was to investigate the effect of moderate ET on the aortic superoxide production index, NAD(P)H oxidase activity, superoxide dismutase activity and vasomotor response in MI rats. Aerobic ET was performed during 11 weeks. Myocardial infarction significantly diminished maximal exercise capacity, and increased vasoconstrictory response to norepinephrine, which was related to the increased activity of NAD(P)H oxidase and basal superoxide production. On the other hand, ET normalized the superoxide production mostly due to decreased NAD(P)H oxidase activity, although a minor SOD effect may also be present. These adaptations were paralleled by normalization in the vasoconstrictory response to norepinephrine. Thus, diminished ROS production seems to be an important mechanism by which ET mediates its beneficial vascular effects in the MI condition

Aerobic Swim Training Restores Aortic Endothelial Function by Decreasing Superoxide Levels in Spontaneously Hypertensive Rats

OBJECTIVE: We aimed to determine whether aerobic training decreases superoxide levels, increases nitric oxide levels, and improves endothelium-dependent vasodilation in the aortas of spontaneously hypertensive rats. METHODS: Spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) were distributed into 2 groups: sedentary (SHRsd and WKYsd, n=10 each) and swimming-trained (SHRtr, n=10 and WKYtr, n=10, respectively). The trained group participated in training sessions 5 days/week for 1 h/day with an additional work load of 4% of the animal’s body weight. After a 10-week sedentary or aerobic training period, the rats were euthanized. The thoracic aortas were removed to evaluate the vasodilator response to acetylcholine (10-10 to 10-4 M) with or without preincubation with L-NG-nitro-L-arginine methyl ester hydrochloride (L-NAME; 10-4 M) in vitro. The aortic tissue was also used to assess the levels of the endothelial nitric oxide synthase and nicotinamide adenine dinucleotide oxidase subunit isoforms 1 and 4 proteins, as well as the superoxide and nitrite contents. Blood pressure was measured using a computerized tail-cuff system. RESULTS: Aerobic training significantly increased the acetylcholine-induced maximum vasodilation observed in the SHRtr group compared with the SHRsd group (85.9±4.3 vs. 71.6±5.2%). Additionally, in the SHRtr group, superoxide levels were significantly decreased, nitric oxide bioavailability was improved, and the levels of the nicotinamide adenine dinucleotide oxidase subunit isoform 4 protein were decreased compared to the SHRsd group. Moreover, after training, the blood pressure of the SHRtr group decreased compared to the SHRsd group. Exercise training had no effect on the blood pressure of the WKYtr group. CONCLUSIONS: In SHR, aerobic swim training decreased vascular superoxide generation by nicotinamide adenine dinucleotide oxidase subunit isoform 4 and increased nitric oxide bioavailability, thereby improving endothelial function

The importance of animal studies in Exercise Science

Abstract The validity and relevance of research with animals for the development of knowledge in Exercise Science have for long been discussed. Given the complexity of the biological systems, the use of animal models offers a significant contribution to uncover new findings about acute and chronic effects of exercise, particularly when these studies in humans have limitations and ethical implications. There have been notable findings using experimental animals either in basic sciences or in clinical studies involving physiology, pharmacology, genetic, biochemistry, urology, endocrinology and cancer. This article presents a brief review of scientific research using animal models with a focus on exercise training as an effective tool for the prophylaxis and treatment of different pathological processes, which are the basis of many concepts taught and used in undergraduate courses and graduate programs, as well as in new researches showed in scientific conference meetings in numerous areas of science