Application Of Pulsed Eletromagnetic Fields In The Early Therapy Of Rats With Acute Skeletal Muscle Contusion

Objective:To set up the model of acute skeletal muscle contusion(ASMC)in rats by the improved device of weight-dropping, and to observe the influence of Paw Withdraw Mechanical Threshold (PWMT)and MyoD expression and the effect of pulsed eletromagnetic fields therapy on skeletal muscle contusion of rats.Method:42 rats were randomly divided into three groups(n=14 each):treatment group,control group and blank control group without any interference.To set up the model of skeletal muscle contusion in treatment group and control group by the improved device of weight-dropping.When the models were successful,PEMFs was only used in treatment group.According to different time points,each group was randomly divided into two subgroups:12h subgroup and 18h subgroup(n=7 each).Behavior and exterior appearance were observed in each group.PWMT of each group were tested at the time of two days before ASMC and before sacrificed.Each rat was sacrificed in the prescribed time,triceps surae was researched by haematoxylin-eosin staining and immunofluorescence techniques,and intensity was measured by fluorescence microscope.Results:1.PWMT of left hind paw after ASMC:T12 and T18 in treatment group and control group was lower than basic pain threshold (TO)(P＜0.0 1);T18 was higher than T12 in treatment group(P＜0.01); T12 in treatment group,both T12 and T18 in control group were lower than blank control group(P＜0.01);and on T18,treatment group was higher than control group(P＜0.01).2.The HE staining showed:the degree of pale cytoplasm and polymorphism of cell nuclei in treatment group were less than control group,but more than blank control group;the amount of inflammation related cells,such as neutrophil,were more than the other two groups, and control group was much serious than blank control group.3.Fluorescence intensity of MyoD:in treatment group and control group,T18 was higher than T12(P＜0.01),and each point in two groups was higher than blank control group(P＜0.01),and on T18 treatment group was higher than control group(P＜0.01).Conclusions:1.The model of skeletal muscle contusion is successful.2.pain threshold(PWMT)was increased on 18h after intervention of PEMFs.3.MyoD expression of rats was increased on 18h after intervention of PEMFs.4.The effect of pulsed eletromagnetic fields therapy was significant on skeletal muscle contusion of rats.