Therapeutic ultrasound decreases mechano-growth factor messenger ribonucleic acid expression after muscle contusion injury

Objective: To examine the influence of nonthermal ultrasound on mechano-growth factor (MGF) messenger ribonucleic acid (mRNA) expression after blunt trauma. Design: A 2x4 factorial multivariate analysis of variance design. Setting: University research laboratory. Animals: Thirty-six 3- to 4-month-old male Wistar rats (mean weight, 280.8 +/- 21.5g). Thirty-two received a bilateral contusion injury to the gastrocnemius via a drop mass technique. Four were control animals. Intervention: Ultrasound treatment (frequency, 3MHz; intensity, 0.3W/cm(2); continuous duty cycle) was started 24 hours postinjury and delivered for 5 minutes daily on 4 consecutive days. Treatment was on the left hindlimb and the contralateral right hindlimb was the nonultrasound control. Main Outcome Measures: Muscle mass (in grams) and MGF mRNA expression as measured via real-time reverse transcriptase polymerase chain reaction. Results: Ultrasound had no effect on muscle mass (F-1,F-28=2.723, P=.110, 1-beta=.357, eta(2)=.089). Ultrasound treatments decreased MGF mRNA expression in the treated limb compared with the nontreated hindlimb (F-1,F-28=6.605, P=.016, 1-beta=.699, eta(2)=. 191). Conclusions: The nonthermal ultrasound treatments resulted in decreased MGF mRNA expression after blunt trauma to the gastrocnemius muscles.