Respiratory muscle training decreases diaphragm DNA damage in rats with heart failure.

Respiratory muscle training (RMT) promotes beneficial effects on respiratory mechanics, heart and lung morphological changes, and hemodynamic variables in rats with heart failure (HF). However, the relation between RMT effects and diaphragm oxidative stress remains unclear. Therefore, the aim of this study was to evaluate the RMT effects on diaphragm DNA damage in HF rats. Wistar rats were allocated into 4 groups: sedentary sham (Sed-Sham, n = 8), trained sham (RMT-Sham, n = 8), sedentary HF (Sed-HF, n = 8), and trained HF (RMT-HF, n = 8). The animals underwent a RMT protocol (30 min/day, 5 days/week for 6 weeks), whereas sedentary animals did not exercise. Groups were compared by a two-way ANOVA and Tukey's post hoc tests. In rats with HF, RMT promoted reduction in pulmonary congestion (p < 0.0001) and left ventricular end diastolic pressure (p < 0.0001). Moreover, RMT produced a decrease in the diaphragm DNA damage in HF rats. This was demonstrated through the reduction in the percentage of tail DNA (p < 0.0001), tail moment (p < 0.01), and Olive tail moment (p < 0.001). These findings showed that a 6-week RMT protocol in rats with HF promoted an improvement in hemodynamic function and reduces diaphragm DNA damage.

Respiratory Muscle Training Improves Chemoreflex Response, Heart Rate Variability, and Respiratory Mechanics in Rats With Heart Failure.

BACKGROUND: The aim of the present report was to evaluate respiratory muscle training (RMT) effects on hemodynamic function, chemoreflex response, heart rate variability, and respiratory mechanics in rats with heart failure (HF rats). METHODS: Wistar rats were divided into 4 groups: sedentary-sham (Sed-Sham, n = 8), respiratory muscle trained-sham (RMT-Sham, n = 8), sedentary-HF (Sed-HF, n = 8) and respiratory muscle trained-HF (RMT-HF, n = 8). Animals were submitted to an RMT protocol performed 30 minutes per day, 5 days per week for 6 weeks, whereas the sedentary animals did not exercise. RESULTS: In HF rats, RMT promoted the reduction of left ventricular end-diastolic pressure, right ventricular hypertrophy, and pulmonary edema. Moreover, RMT produced a reduction in pressure response during chemoreflex activation, sympathetic modulation, and sympathetic vagal balance in addition to an increase in parasympathetic modulation. Also after RMT, HF rats demonstrated a reduction in respiratory system resistance, tissue resistance, Newtonian resistance, respiratory system compliance, and quasistatic compliance. CONCLUSIONS: These findings suggested that 6 weeks of RMT in HF rats promoted beneficial adaptations in hemodynamics, autonomic function, and respiratory mechanics and attenuated pressure response evoked by chemoreflex activation in HF rats.