Sodium overload during postnatal phases impairs diastolic function and exacerbates reperfusion arrhythmias in adult rats.

Sodium overload during childhood impairs baroreflex sensitivity and increases arterial blood pressure and heart rate in adulthood; these effects persist even after high-salt diet (HSD) withdrawal. However, the literature lacks details on the effects of HSD during postnatal phases on cardiac ischemia/reperfusion responses in adulthood. The current study aimed to elucidate the impact of HSD during infancy adolescence on isolated heart function and cardiac ischemia/reperfusion responses in adulthood. Male 21-day-old Wistar rats were treated for 60 days with hypertonic saline solution (NaCl; 0.3M; experimental group) or tap water (control group). Subsequently, both groups were maintained on a normal sodium diet for 30 days. Subsequently, the rats were euthanized, and their hearts were isolated and perfused according to the Langendorff technique. After 30 min of the basal period, the hearts were subjected to 20 min of anoxia, followed by 20 min of reperfusion. The basal contractile function was unaffected by HSD. However, HSD elevated the left ventricular end-diastolic pressure during reperfusion (23.1 ± 5.2 mmHg vs. 11.6 ± 1.4 mmHg; p < 0.05) and increased ectopic incidence period during reperfusion (208.8 ± 32.9s vs. 75.0 ± 7.8s; p < 0.05). In conclusion, sodium overload compromises cardiac function after reperfusion events, diminishes ventricular relaxation, and increases the severity of arrhythmias, suggesting a possible arrhythmogenic effect of HSD in the postnatal phases.

Cardioprotective Effects of the 4-Week Aerobic Running Exercises Before Treatment with Doxorubicin in Rats.

Doxorubicin is associated with cardiotoxicity, and physical exercise seeks to minimize the toxic effects of doxorubicin through physiological cardiac remodeling, as well as the reduction of oxidative stress, evidenced by previous studies. This study aimed to analyze whether running training before treatment with doxorubicin influences tolerance to physical exertion and cardiotoxicity. Thirty-nine male Wistar rats, aged 90 days and weighing between 250 and 300 g, were divided into 4 groups: Control (C), Doxorubicin (D), Trained (T), and Trained + Doxorubicin (TD). Animals in groups T and DT were submitted to treadmill running for 3 weeks, 5 times a week at 18 m/min for 20-30 min before treatment with doxorubicin. Animals in groups D and DT received intraperitoneal injections of doxorubicin hydrochloride three times a week for two weeks, reaching a total cumulative dose of 7.50 mg/kg. Our results show an increase in total collagen fibers in the D group (p = 0.01), but no increase in the TD group, in addition to the attenuation of the number of cardiac mast cells in the animals in the TD group (p = 0.05). The animals in the TD group showed maintenance of tolerance to exertion compared to group D. Therefore, running training attenuated the cardiac damage caused by the treatment with doxorubicin, in addition to maintaining the tolerance to exertion in the rats.

Forced internal desynchrony induces cardiometabolic alterations in adult rats.

Disruptions in circadian rhythms have been associated with several diseases, including cardiovascular and metabolic disorders. Forced internal desynchronization induced by a period of T-cycles of 22 h (T22 protocol) reaches the lower limit of entrainment and dissociates the circadian rhythmicity of the locomotor activity into two components, driven by different outputs from the suprachiasmatic nucleus (SCN). The main goal of this study was to evaluate the cardiovascular and metabolic response in rats submitted to internal desynchronization by T22 protocol. Male Wistar rats were assigned to either a control group subjected to a usual T-cycles of 24 h (12 h-12 h) or an experimental group subjected to the T22 protocol involving a 22-h symmetric light-dark cycle (11 h-11 h). After 8 weeks, rats subjected to the T22 exhibited desynchrony in their locomotor activity. Although plasma glucose and insulin levels were similar in both groups, desynchronized rats demonstrated dyslipidemia, significant hypertrophy of the fasciculate zone of the adrenal gland, low IRB, IRS2, PI3K, AKT, SOD and CAT protein expression and an increased expression of phosphoenolpyruvate carboxykinase in the liver. Furthermore, though they maintained normal baseline heart rates and mean arterial pressure levels, they also presented reduced baroreflex sensitivity. The findings indicate that circadian timing desynchrony following the T22 protocol can induce cardiometabolic disruptions. Early hepatic metabolism dysfunction can trigger other disorders, though additional studies are needed to clarify the causes.

Postnatal early overfeeding induces cardiovascular dysfunction by oxidative stress in adult male Wistar rats.

AIMS: Obesity is associated with innumerous comorbidities, including cardiovascular diseases, that occur by various mechanisms, including hyperactivation of the renin angiotensin system, oxidative stress and cardiovascular overload. Postnatal early overfeeding (PO) leads to metabolic imprinting that induces weight gain throughout life, and in this paper, we aimed to evaluate cardiovascular parameters and cardiac molecular changes due to obesity induced early in life by PO. MAIN METHODS: Male Wistar rats (120-days-old), raised in normal (NL) or small litters (SL), were submitted to cardiac assessment by transthoracic echocardiography and blood pressure evaluation. Thereafter, the hearts and aorta rings from these animals were submitted to ex-vivo isolated assays. Still, cardiac morphological and molecular analyses were performed. KEY FINDINGS: PO induced ventricular hypertrophy, raised blood pressure, increased fibrosis, and ex-vivo cardiac dysfunction in the SL group. Furthermore, SL animals presented impaired vascular relaxation and increased vascular constriction responses. Besides functional alterations, SL animals presented augmented RAB-1b and SOD-1, despite no changes in RAS receptors expression or Akt/eNOS pathway. SIGNIFICANCE: Taken together, our results consolidate the knowledge that the PO during lactation is critical for cardiometabolic programming, leading to oxidative stress and cardiac remodeling in later stages of life.

Proprioceptive exercise with bosu maximizes electromyographic activity of the ankle muscles / Exercício proprioceptivo com bosu maximiza atividade eletromiográfica dos músculos do tornozelo

Ankle sprains are commonly related to sporty activities and often associated with decreases in sensorimotor control, including proprioception, muscle strength and balance. The use of unstable surfaces in the fields of rehabilitation and general fitness has been shown to be effective in increasing the sensory efficiency of soft tissues that stabilize the knee and ankle as well as improving the agonist-antagonist co-contraction. The aim of this study was to analyze the EMG activity of the ankle muscles ­ the tibialis anterior (TA), peroneus longus (PL) and medial head of the gastrocnemius (GM) during proprioceptive exercises using the BOSU compared to other devices traditionally used (balance platform, trampoline and proprioceptive disk). Eleven male volunteers were recruited and data collection was performed using single differential surface electrodes. The EMG signal was recorded and expressed as root mean square, which was normalized by the maximum voluntary isometric contraction. The data were subjected to parametric statistical analysis, using the analysis of variance (ANOVA) for repeated measures. The results showed that the BOSU provided greater activity in the ankle muscles than the most proprioceptive devices, accordingly, the BOSU is a device that should be employed to diversify programs of prevention/rehabilitation for lower limb injuries, preferentially in advanced stages of these approaches.

As entorses de tornozelo são comumente relacionadas com atividades desportivas e muitas vezes estão associados com diminuição no controle sensório-motor, incluindo a propriocepção, força muscular e equilíbrio. A utilização de superfícies instáveis nas áreas de reabilitação e condicionamento físico geral têm sido eficaz no aumento da eficiência sensorial dos tecidos moles que estabilizam o joelho e tornozelo e na melhora da cocontração agonistaantagonista. Desta forma, o objetivo deste estudo foi analisar a atividade eletromiográfica dos músculos tibial anterior (TA), fibular longo (FL) e cabeça medial do gastrocnêmio (GM) durante o exercício proprioceptivo com bosu e comparar com diferentes aparelhos tradicionalmente utilizados (balancinho, cama elástica e disco proprioceptivo). Onze voluntários do gênero masculino foram recrutados e a coleta de dados foi realizada utilizando-se eletrodos de superfície diferencial simples. O sinal eletromiográfico foi quantificado pela Raiz Quadrada da Média (root mean square -RMS) e normalizado pela Contração Isométrica Voluntária Máxima. Os dados obtidos foram submetidos à análise estatística paramétrica, empregando-se teste de análise de variância de medidas repetidas (ANOVA). Os resultados demonstraram que o bosu proporcionou maior atividade nos músculos do tornozelo em relação a maioria dos aparelhos proprioceptivos , desta forma, o bosu é um dispositivo que deve ser utilizado para diversificar um programa de prevenção ou reabilitação de lesões de membro inferior, preferencialmente em estágios avançados destes programas.

Ajustes Cardiovasculares Induzidos pela Desidratação Crônica nas Fases Iniciais do Período Pós-Natal em Ratos Acordados / Cardiovascular Adjustments Induced by Chronic Dehydration in the Early Stages of PostNatal in Awake Rats

Alterações da osmolaridade do compartimento extracelular podem alterar o volume, o metabolismo e a função celular. Em virtude disso,varias complicações podem ser observadas, dentre elas a hipertensão arterial. Assim, a regulação precisa do volume e da osmolaridade docompartimento extracelular é fundamental para a manutenção das funções normais do organismo e da sobrevivência. O objetivo desse estudofoi avaliar os parâmetros hemodinâmicos através de desidratação induzida por furosemide em ratos jovens não anestesiados. Foram utilizados,ratos Wistar com cinco dias de idade, divididos em dois grupos experimentais, um controle (n=10) e um submetido ao tratamento comFurosemide (10mg/kg de massa corpórea, n=12), administrado três vezes por semana, durante dois meses. Após o tratamento, os animaisforam anestesiados para cateterização com cânulas inseridas na artéria e veia femorais, através de um corte inguinal de um dos lados. Ascânulas foram transpassadas subcutaneamente através do dorso do animal e foram exteriorizadas. Os experimentos foram realizados apósuma recuperação de 48h do procedimento cirúrgico, utilizando um amplificador e um software. Os resultados obtidos demonstraram que nãohouve diferenças nos testes induzidos de ingestão de água durante os 120 minutos analisados, quando comparados o grupo controle e o grupofurosemide, respectivamente. Na análise da pressão arterial méia e frequência cardíaca, não foi observada modificação dos níveis basais. Essepadrão de resposta também foi obtido quando analisado a PAS e PAD. Com esses resultados, concluímos que a depleção do compartimentoextracelular induzido pela administração de furosemide em ratos jovens não é fator determinante para alteração dos parâmetros hemodinâmicosna fase adulta.

Changes in osmolarity of the extracellular compartment may change the volume, metabolism and cellular function. As a result, manycomplications can be observed, among them hypertension. Thus, precise regulation of the volume and osmolality of the extracellularcompartment is critical to maintaining normal body functions and survival. Previous results demonstrated that despite anesthetized ratssubmitted to chronic diuretic treatment showed no change in sensitivity to sodium and water, an increased arterial pressure was observed. Thepresent study aims to assess hemodynamic parameters through furosemide-induced dehydration in anaesthetized young rats. Five days oldWistar rats divided into two groups, a control (n = 10) and a group subjected to subcutaneous treatment with the diuretic Furosemide (10mg/kg of body weight, n = 12) were used. After treatment, the animals were anesthetized for the implantation of the polyethylene tubes, which wereinserted into the artery (for records cardiovascular variables) and femoral vein through a cut inguinal one side (left / right). The cannulaswere transfixed subcutaneously through the back of the animal and were exteriorized. Data were recorded after a 48h recovery of the surgicalprocedure, using an amplifier and software. No differences in induced intake test of water within 120 minutes were observed. With respect tomean arterial pressure and heart rate, no modification on baseline levels were observed (PAM: 99.4 ± 1.9 mmHg, control vs 102.7 ± 1 mmHg,furosemide; FC: 362.5 ± 5.2 bpm, control vs 364.9 ± 7 bpm, furosemide). This response pattern was also obtained for SBP (124.3 ± 6 mmHg,control vs 130 ± 1.6 mmHg, furosemide) and DBP (82.2 ± 1.9 mmHg, control vs 82.1 ± 1 mmHg, furosemide). We concluded that depletionof the extracellular compartment induced by furosemide administration in young rats is not a determining factor to change the hemodynamicparameters in adulthood.