Analysis of cardiopulmonary resistance under different loads in aerobic exercises / Análise da resistência cardiopulmonar sob diferentes cargas em exercícios aeróbicos / Análisis de la resistencia cardiopulmonar bajo diferentes cargas en ejercicios aeróbicos

ABSTRACT Introduction The key objective of aerobic exercise is enhancing cardiorespiratory endurance. On the national gymnastics plan implementation, the idea of lifelong sports was gradually accepted by the masses, and the aerobic gymnastics concept was sweeping the world. Objective Analyze the cardiorespiratory endurance responses in female college students under different frequencies in aerobic exercise. Methods 20 female professors and civilian women were randomly selected and divided into two groups. The experimental group performed 45 and 90 minutes of aerobic exercise to analyze changes in cardiopulmonary function before and after each exercise. Results After 16 weeks of aerobic exercise with different loads, all young women who had participated in the program training showed a significant increase in vital capacity and maximal oxygen uptake capacity. The vital capacity of the 90-min aerobic exercise group was significantly higher than that of the 45-min aerobic exercise group (P<0.05). Conclusion The establishment of a cardiorespiratory endurance response model can accurately analyze the effects of different aerobic exercise frequencies on cardiorespiratory endurance. Evidence Level II; Therapeutic Studies - Investigating the results.

RESUMO Introdução O principal objetivo do exercício aeróbico é melhorar a resistência cardiorrespiratória. Com a implementação do plano nacional de ginástica, a ideia de esportes para toda a vida é gradualmente aceita pelas massas e o conceito de ginástica aeróbica está popularizando-se. Objetivo Analisar as respostas de resistência cardiorrespiratória em estudantes universitárias sob distintas frequências no exercício aeróbico. Métodos 20 jovens professoras e mulheres civis foram aleatoriamente selecionadas e divididas em dois grupos. O grupo experimental executou exercícios aeróbicos de 45 e 90 minutos, sob análise das alterações na função cardiopulmonar antes e depois de cada exercício. Resultados Após 16 semanas de exercício aeróbico com diferentes cargas, todas as mulheres jovens que participaram do treinamento mostraram um aumento significativo na capacidade vital e na capacidade máxima de absorção de oxigênio. A capacidade vital do grupo de exercícios aeróbicos de 90 minutos foi significativamente maior do que a do grupo de exercícios aeróbicos de 45 minutos (P<0,05). Conclusão O estabelecimento de um modelo de resposta de resistência cardiorrespiratória pode analisar com precisão os efeitos de diferentes frequências de exercício aeróbico sobre a resistência cardiorrespiratória. Nível de evidência II; Estudos Terapêuticos - Investigação de Resultados.

RESUMEN Introducción El objetivo principal del ejercicio aeróbico es mejorar la resistencia cardiorrespiratoria. Con la puesta en marcha del plan nacional de gimnasia, la idea de los deportes de por vida es gradualmente aceptada por las masas y el concepto de la gimnasia aeróbica está popularizándose en todo el mundo. Objetivo Analizar las respuestas de resistencia cardiorrespiratoria en estudiantes universitarias bajo diferentes frecuencias en el ejercicio aeróbico. Métodos Se seleccionaron al azar 20 profesoras jóvenes y mujeres civiles y se dividieron en dos grupos. El grupo experimental realizó ejercicios aeróbicos de 45 y 90 minutos, bajo el análisis de los cambios en la función cardiopulmonar antes y después de cada ejercicio. Resultados Tras 16 semanas de ejercicio aeróbico con diferentes cargas, todas las mujeres jóvenes que participaron en el entrenamiento mostraron un aumento significativo de la capacidad vital y de la capacidad máxima de captación de oxígeno. La capacidad vital del grupo de ejercicio aeróbico de 90 minutos fue significativamente mayor que la del grupo de ejercicio aeróbico de 45 minutos (P<0,05). Conclusión El establecimiento de un modelo de respuesta a la resistencia cardiorrespiratoria puede analizar con precisión los efectos de diferentes frecuencias de ejercicio aeróbico sobre la resistencia cardiorrespiratoria. Nivel de evidencia II; Estudios terapéuticos - Investigación de resultados.

Importance of AT1 and AT2 receptors in the nucleus of the solitary tract in cardiovascular responses induced by a high-fat diet.

A high-fat diet (HFD) induces an increase in arterial pressure and a decrease in baroreflex function, which may be associated with increased expression of angiotensin type 1 receptor (AT1R) and pro-inflammatory cytokine genes and reduced expression of the angiotensin type 2 receptor (AT2R) gene within the nucleus of the solitary tract (NTS), a key area of the brainstem involved in cardiovascular control. Thus, in the present study, we evaluated the changes in arterial pressure and gene expression of components of the renin-angiotensin system (RAS) and neuroinflammatory markers in the NTS of rats fed a HFD and treated with either an AT1R blocker or with virus-mediated AT2R overexpression in the NTS. Male Holtzman rats (300-320 g) were fed either a standard rat chow diet (SD) or HFD for 6 weeks before commencing the tests. AT1R blockade in the NTS of HFD-fed rats attenuated the increase in arterial pressure and the impairment of reflex bradycardia, whereas AT2R overexpression in the NTS only improved the baroreflex function. The HFD also increased the hypertensive and decreased the protective axis of the RAS and was associated with neuroinflammation within the NTS. The expression of angiotensin-converting enzyme and neuroinflammatory components, but not AT1R, in the NTS was reduced by AT2R overexpression in this site. Based on these data, AT1R and AT2R in the NTS are differentially involved in the cardiovascular changes induced by a HFD. Chronic inflammation and changes in the RAS in the NTS may also account for the cardiovascular responses observed in HFD-fed rats.

Increased Expression of Macrophage Migration Inhibitory Factor in the Nucleus of the Solitary Tract Attenuates Renovascular Hypertension in Rats.

BACKGROUND: Macrophage migration inhibitory factor (MIF) is an intracellular inhibitory regulator of the actions of angiotensin II in the central nervous system. Renovascular hypertensive 2-kidney, 1-clip (2K1C) rats have an increased activity of the renin-angiotensin system and a decrease in baroreflex function compared to normotensive (NT) rats. In the present study, we tested the effects of MIF overexpression within the nucleus of the solitary tract (NTS), a key brainstem region for cardiovascular regulation, on the development of hypertension, on baroreflex function, and on water and food intake in 2K1C rats. METHODS: Holtzman NT rats received a silver clip around the left renal artery to induce 2K1C hypertension. Three weeks later, rats were microinjected in the NTS with AAV2-CBA-MIF, to increase the expression of MIF, or with the control vector AAV2-CBA-enhanced green fluorescent protein. Mean arterial pressure (MAP) and heart rate were recorded by telemetry. Baroreflex function was tested, and water and food intake were also measured. RESULTS: Increasing MIF expression in the NTS of 2K1C rats attenuated the development of hypertension, reversed the impairment of baroreflex function, and reduced the increase in water intake. In contrast to 2K1C rats, similar increases in MIF expression in the NTS of NT rats produced no changes in baseline MAP, baroreflex function, or water intake. CONCLUSIONS: These results indicate that an increased expression of MIF within the NTS attenuates the development of hypertension and restores the baroreflex function in 2K1C rats.

Overexpression of AT2R in the solitary-vagal complex improves baroreflex in the spontaneously hypertensive rat.

The aim of this study was to investigate the physiological effects of increased angiotensin II type 2 receptor (AT2R) expression in the solitary-vagal complex (nucleus of the solitary tract/dorsal motor nucleus of the vagus; NTS/DVM) on baroreflex function in non-anaesthetised normotensive (NT) and spontaneously hypertensive rats (SHR). Ten week old NT Holtzman and SHR were microinjected with either an adeno-associated virus expressing AT2R (AAV2-CBA-AT2R) or enhanced green fluorescent protein (control; AAV2-CBA-eGFP) into the NTS/DVM. Baroreflex and telemetry recordings were performed on four experimental groups: 1) NTeGFP, 2) NTAT2R, 3) SHReGFP and 4) SHRAT2R (n=4-7/group). Following in-vivo experimental procedures, brains were harvested for gene expression analysis. Impaired bradycardia in SHReGFP was restored in SHR rats overexpressing AT2R in the NTS/DMV. mRNA levels of angiotensin converting enzyme decreased and angiotensin converting enzyme 2 increased in the NTS/DMV of SHRAT2R compared to SHReGFP. Increased levels of pro-inflammatory cytokine mRNA levels in the SHReGFP group also decreased in the SHRAT2R group. AT2R overexpression did not elicit any significant change in mean arterial pressure (MAP) in all groups from baseline to 4weeks post viral transfection. Both SHReGFP and SHRAT2R showed a significant elevation in MAP compared to the NTeGFP and NTAT2R groups. Increased AT2R expression within the NTS/DMV of SHR was effective at improving baroreflex function but not MAP. We propose possible mediators involved in improving baroreflex are in the ANG II/ACE2 axis, suggesting a potential beneficial modulatory effect of AT2R overexpression in the NTS/DMV of neurogenic hypertensive rats.