Conversion of the rabbit gracilis muscle for transposition as a neoanal sphincter by electrical stimulation.
To re-establish anal function in fecally incontinent patients it may be feasible to transpose the gracilis muscle around the anal canal, using electrical stimulation to trigger contraction. However, because the fast-twitching gracilis muscle is incapable of prolonged contraction without fatigue, it is necessary to convert it to a slow-twitching, fatigue-resistant muscle. We demonstrated this conversion by longterm electrical stimulation at low frequencies using a rabbit model. The nerve to the gracilis muscle was continuously stimulated at 2 Hz, 5 Hz, and 10 Hz for 2, 4, or 6 weeks. In the 6-week conditioning group, the percentage of type I fibers, identified by ATPase staining, increased as the conditioning frequency became higher, but the twitch contraction speed reduced with conditioning at a frequency of more than 5 Hz. The fatigue resistance improved by conditioning at 10 Hz, and conversion occurred in 6 weeks. Thus, we concluded that conditioning at 10 Hz for 6 weeks can convert rabbit gracilis muscle to a slow-twitching, fatigue-resistant muscle suitable for use as a neoanal sphincter.
Shatari
T
T
Department of Surgery, School of Medicine, Keio University, Tokyo, Japan.
Teramoto
T
T
Kitajima
M
M
Minamitani
H
H
D001003:Anal Canal / Q000601:surgery*; D000818:Animals; D004558:Electric Stimulation / Q000379:methods*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009132:Muscles / Q000502:physiology* / Q000637:transplantation*; D011817:Rabbits