Muscle fiber characteristics in patients with peripheral arterial disease.
OBJECTIVE
There have been conflicting reports of muscle fiber type changes in patients with peripheral arterial disease (PAD). The purpose of this study was to examine the myosin heavy chain (MHC) expression as well as histochemical changes in the gastrocnemius muscle in patients with symptomatic PAD.


METHODS
Needle biopsy specimens were obtained from the medial gastrocnemius of 14 subjects with PAD (mean age (+/- SD), 69.7 +/- 4.8 yr) and eight activity-matched control subjects (mean age, 65.1 +/- 6.6 yr). Ankle-brachial index was assessed using Doppler ultrasound to determine the hemodynamic status of the patients, and maximal walking performance was determined during a graded treadmill test. Expression of MHC isoforms was determined by SDS-PAGE.


RESULTS
The proportion of MHC I was significantly smaller in PAD than in the controls (45.6 +/- 9.1% vs 58.8 +/- 15.0%). The proportion of MHC IIx was also larger in the subjects with PAD compared with the controls (22.9 +/- 9.1% vs 16.0 +/- 11.3%). In addition, there was a significant decrease in the cross-sectional area of the type I and type IIA fibers in the subjects with PAD as well as enhanced capillary density.


CONCLUSIONS
This study showed a significant modification in the expression of MHC isoforms and muscle fiber type in the gastrocnemius in patients with symptomatic PAD. These results suggest that muscle ischemia resulting from PAD is an important factor in causing the adaptations in the contractile apparatus of the muscle.
McGuigan
M R
MR
Department of Exercise and Sport Science, University of Wisconsin-La Crosse, La Crosse, WI 54601, USA. mcguigan.mich@uwlax.edu
Bronks
R
R
Newton
R U
RU
Sharman
M J
MJ
Graham
J C
JC
Cody
D V
DV
Kraemer
W J
WJ
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000368:Aged; D001707:Biopsy, Needle; D001794:Blood Pressure; D002196:Capillaries; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000378:metabolism* / Q000473:pathology*; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D016491:Peripheral Vascular Diseases / Q000378:metabolism* / Q000473:pathology*; D012016:Reference Values
D000251:Adenosine Triphosphatases; D018995:Myosin Heavy Chains