Effects of laser therapy and therapeutic ultrasound on the protein expression of myosin heavy chain isoforms during the skeletal muscle repair of rats

Abstract

Muscle injuries are a major clinical conditions found in the rehabilitation center. The main therapeutic resources used in the rehabilitation center for the treatment of muscle injuries are Low-Level Laser Therapy (LLLT) and Therapeutic Ultrasound (US). Both of them have demonstrated positive effects on muscle repair process. However, there is no description in the literature as could influence the determination of the phenotype of newly formed fibers and the type of myosin heavy chain (MHC) expressed. Furthermore, there is a need to determine the molecular mechanisms involved as well as the methodology and dosimetric parameters. The objective of this study will be evaluate the effect of LLLT and US on the protein expression of MHC isoforms during the repair process of skeletal muscle in rats. Wistar rats will be divided into four groups: 1) control group; 2) non-treated injury group; 3) Injury treated with LLLT; and 4) Injury treated with US. The study periods will be 3, 7 and 14 days. Cryoinjury will be induced by two applications of a metal probe cooled in liquid nitrogen directly onto the belly of the tibialis anterior (TA) muscle. The treatment will be performed using the LLLT [MMoptics AsGaAl equipment (» 780nm)] with energy density of 10 J/cm², output power of 40 mW and time of 10 seconds, and the treatment with US will be performed using the Sonomaster® equipment with the frequency of 1 MHz, intensity of 0.4 W/cm2, pulsed mode at 1:4 cycles, stationary application for 3 minutes. For the protein expression analysis the Western Blotting technique will be performed using specific antibodies to the MHC type I and II. (AU)