Electrically stimulated sartorius neosphincter: Canine model of activation and skeletal muscle transformation

Abstract

The sartorius muscle was transposed into the abdominal cavity of six dogs, passed around a Thiry–Vella loop and sutured to itself to form a neosphincter. The muscle was activated by electrical stimulation and on contraction the neosphincter stopped or reduced the flow of saline through the Thiry–Vella loop in all animals until the onset of muscle fatigue. Continuous low frequency stimulation was used to transform the skeletal muscle, and when studied after a mean of 8 weeks of stimulation (range 6–11 weeks) the neosphincter stopped the flow for a significantly longer period of time (P = 0·027). Associated with the improved neosphincter function was a significant decrease in the fusion frequency (P = 0·003) and prolongation of the stimulus–peak tension time as assessed by a strain gauge sutured to the neosphincter muscle (P = 0·002). The changes in the contraction properties of the skeletal muscle suggest that continuous low frequency stimulation transformed the muscle fibres from type 2 to type 1, resulting in improved fatigue resistance and potential for continuous sphincter activity.