Is myoelectric activity transmittable from one muscle to another: an experimental study

In contrast to other striated muscles in the body, pelvic floor muscles possess resting electric activity. We have demonstrated that this activity was due to smooth muscle fibers detected in the levator ani muscle (LAM) which presumably develop in adaptation to variations in the intraabdominal pressure and visceral weight action.

The current communication tries to answer the question whether this resting myoelectric activity is transmittable to other muscles which lack such activity.

The LAM and obturator internus muscle (OIM) were exposed in 14 mongrel dogs through a paraanal incision. The resting EMG activity of both muscles was recorded. The border of the LAM closest to its origin at the white line, was released and sutured to the obturator fascia. The EMG activity of both the LAM and OIM was recorded at rest and on LAM stimulation. The EMG recording was repeated after suturing of the LAM to the OIM whose fascia had been removed. The test was repeated after LAM anesthetization.

Resting and stimulated EMG activity was recorded in the LAM, but not in the OIM, before and after suturing the LAM to the obturator fascia. On removing the obturator fascia, both muscles recorded similar EMG activity at rest and on LAM stimulation (p > 0.05, p > 0.05, respectively). Thirty minutes from LAM anesthetization both muscles showed no EMG activity at rest or on LAM stimulation; after 3 hours, the 2 muscles recorded an activity similar to that before anesthetization (p > 0.05).

The myoelectric activity can be transmitted to defasciated muscles. This finding may be useful in electrostimulation therapy and in developing type 1 fibers in striated muscles.