Contractile response of different segments of the latissimus dorsi muscle to chronic stimulation

Objective: This study was planned to investigate if there is any difference in terms of the muscle force between the distal and proximal segments of the latissimus dorsi muscle.Subjects and Methods: An implantable mock circulation system was placed around the latissimus dorsi muscle. The wrapping procedure around the implantable mock circulation was performed by using two different latissimus dorsi muscle segments. In group 1, the very proximal and in group 2, very distal part of the latissimus dorsi were wrapped. The main differences is the blood supply to the distal part of the latissimus dorsi that was interrupted during dissection. During the stimulation period which lasted 120 minutes, the pressure developed in this system and adenosine triphosphate (ATP) levels were measured.Results: The stimulation at 20 Hz did not result in any change in pressure and metabolic data. When it was switched to 43 and 85 Hz, ATP levels decreased with a resultant drop in pressure in group 2. However ATP levels were 15.9±2.2 μmol/gr and 14.8±2.5 μmol/gr in group 1, 12.0±1.4 μmol/gr and 6.1±1.2 μmol/gr in group 2 at 43 and 85 Hz respectively (p<0.05) at the end of the 90 minutes. The pressures at the same time interval were 89±11 and 102±7 mmHg in group 1, 61±7 and 65±8 mmHg in group 2 (p<0.05).Conclusion: In this study, we demonstrated that changes in the distal segment of the latissimus dorsi muscle affects its performance in terms of metabolic and pressure changes during high frequency electrical stimulation at 43 and 85 Hz.