O bloqueio da atividade nitrérgica no tendão de ratos submetidos à tenotomia com sutura acelera a regeneração muscular

Abstract

Muscle atrophy is an immediate response of muscle under both situations of reduced tension and unloading. It is characterized by morphological changes, increase in muscular proteolysis, loss of mass and decrease in fiber area which are implicated in functional deficits, affecting the life quality of individuals. Tendon ruptures induce muscle atrophy due to intrinsic functional connection between both structures. Our previous work has shown that local inhibition of nitric oxide synthesis accelerated histological recovery in tendon and functional improvement in tenotomized animals. The present study was undertaken in order to evaluate the effects of local nitrergic inhibition on pattern of skeletal muscle regeneration after tenotomy. Skeletal muscle atrophy was induced by experimental rupture of the calcaneal tendon followed by suture. Animals were divided in the following groups, control, rupture, rupture + vehicle (0.9 % Saline) and rupture + L-nitroarginine methyl ester (5 mM L-NAME). Muscle samples were obtained 14 and 21 days after experimental surgical procedure. Total protein was measured by Bradford method. Samples were also used to qualitative and quantitative histological processing to determination of muscle fiber area and central core lesion. Animals were weighed at 0, 7, 14 and 21 days after surgery. Animals showed no significant differences in body weights, suggesting that drug had a local action. Group treated with L-NAME showed significant decrease in number of central core lesions at 14th postoperative day and increase in protein levels and fiber area at 21th day. Taken together our results suggest that local NOS inhibition had a beneficial effect after tendon rupture with regard to attenuation of atrophy, contributing for acceleration of muscle regeneration.