Respiratory muscle training improves diaphragm citrate synthase activity and hemodynamic function in rats with heart failure

Abstract INTRODUCTION: Enhanced respiratory muscle strength in patients with heart failure positively alters the clinical trajectory of heart failure. In an experimental model, respiratory muscle training in rats with heart failure has been shown to improve cardiopulmonary function through mechanisms yet to be entirely elucidated. OBJECTIVE: The present report aimed to evaluate the respiratory muscle training effects in diaphragm citrate synthase activity and hemodynamic function in rats with heart failure. METHODS: Wistar rats were divided into four experimental groups: sedentary sham (Sed-Sham, n=8), trained sham (RMT-Sham, n=8), sedentary heart failure (Sed-HF, n=7) and trained heart failure (RMT-HF, n=7). The animals were submitted to a RMT protocol performed 30 minutes a day, 5 days/week, for 6 weeks. RESULTS: In rats with heart failure, respiratory muscle training decreased pulmonary congestion and right ventricular hypertrophy. Deleterious alterations in left ventricular pressures, as well as left ventricular contractility and relaxation, were assuaged by respiratory muscle training in heart failure rats. Citrate synthase activity, which was significantly reduced in heart failure rats, was preserved by respiratory muscle training. Additionally, a negative correlation was found between citrate synthase and left ventricular end diastolic pressure and positive correlation was found between citrate synthase and left ventricular systolic pressure. CONCLUSION: Respiratory muscle training produces beneficial adaptations in the diaphragmatic musculature, which is linked to improvements in left ventricular hemodynamics and blood pressure in heart failure rats. The RMT-induced improvements in cardiac architecture and the oxidative capacity of the diaphragm may improve the clinical trajectory of patients with heart failure.

Age related changes in gastrocnemius, diaphragm and heart muscles with special reference to SDH and m-ATPase.

Age related histochemical and biochemical decrease in succinic dehydrogenase (SDH) and myofibrillar ATPase (m-ATPase) activity was observed in diaphragm, leg and heart muscles of rat. The effects of ageing varied in intensity in different muscle types and were more pronounced in fast muscles. Decrease in m-ATPase may be the result of age related decrease in number of contractile elements revealed by low content of electrophoretically analysed myofibrillar proteins. Restructuring in nerve muscle junction reported, was in relation to normal variation in functional demands of rat from different age groups because of transient changes in work load.

Globular and asymmetric forms of acetylcholinesterase in the rat levator ani muscle

The endplate (+EP) and non-endplate (-EP) distribution of molecular formas of acetylcholinesterase (AChE) was compared in the dimorphic levator ani and disphragm muscles from adult male rats. Enzyme activity was measured by the thicholine method and AchE forms were separated on the basis of solubility in sodium phosphate buffer of different ionic strenght. For the dimorphic levator ani muscle, total AchE activity was 342.6 ñ 18.9 nmol ASCh hydrolyzed min-1 muscle-1, 90% of which was globular and predominated in the-EP region (78%). The asymmetric forms were almost exclusively detected in the +EP region (9%). In diaphragm muscler, total AChE activity was 176.7 ñ 11.0 units; 66% was mainly globular and located in the-EP region (56%); the asymmetric forms (34%) were either in -EP (11%) or + EP (23%) regions. Thus, a greater proportion of globular form was presented in the dimorphic levator ani muscle than in diaphragm muscle. In view of the control exerted by testosterone on dimorphic muscles, its is suggested that the grater synthesis of the globular form in the levator ani occurs under the trophic influence of testosterone