Laceration in rat gastrocnemius. Following-up muscle repairing by ultrasound biomicroscopy (in vivo), contractility test (ex vivo) and histopathology.

PURPOSE Implement a laceration protocol of the rat lateral gastrocnemius (LG) and following-up its repair with ultrasound biomicroscopy (UBM), contractility tests and histology. METHODS Sixty-three male Wistar rats were distributed into two groups. One, with sub-groups GI, GII and GIII (n=12), each containing right LG lacerated (n=6), control and sham (n=3) animals. LG muscles in GI, GII and GIII were inspected by UBM (40 MHz) immediately after, 14 and 28 days post-surgery and thereafter excised with four (GI), 14 (GII) and 28 (GIII) days post-surgery for histology. Animals in second group were distributed into right LG lacerated and control sub-groups. LG muscles in lacerated sub-group were submitted to contractility tests at four (n=8), 14 (n=8) and 28 (n=8) days post-surgery, while in the control sub-group (n=5) were submitted to contractility tests along the course of the experiments. RESULTS Descriptive findings agreed between the lesion model, muscle repair, UBM images and histology. Contractility results for right LG were different (p<0.05) between control and injured muscle with four and 14 days post-surgery, at tetanic stimulating frequencies (50 and 70 Hz). CONCLUSION A laceration protocol of the lateral gastrocnemius was implemented and ultrasound biomicroscopy, contractility and histology findings agreed regarding the following-up of injured muscle repair.