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.