Angiotensin II may play a role in overload induced skeletal muscle hypertrophy in the rat model

ABSTRACT

The aim of the present work was to investigate whether the renin angiotensin system plays a role in overload induced hypertrophy in skeletal muscles. Six groups of male rats were studied, each comprising six animals Group 1 comprised sham operated non- overloaded animals; group 2 comprised animals in which plantaris muscles of both hind limbs were mechanically overloaded by surgical sectioning of soleus and gastronemius muscles; group 3 comprised sham operated animals treated with angiotensin converting enzyme [ACE] inhibitor for two weeks; group 4 comprised mechanically overloaded animals treated with ACE inhibitor for two weeks; group 5 comprised sham operated animals treated with angiotensin receptor [AT1] blocker for two weeks and group 6 comprised mechanically overloaded animals treated with AT1 blocker for two weeks. At the end of two weeks twitch characteristics [twitch tension, time of peak tension and half relaxation time] and peak titanic force were assessed in situ. Plantaris muscle and heart wet weight normalized to tibia length and plantaris cross sectional area were measured. Serum ACE activity was also measured. It was concluded that angiotensin II possibly through an effect mediated on AT1 receptors is involved in skeletal muscle hypertrophy and fiber type transition in the fast twitch plantaris muscle subjected to mechanical overload