Altered fiber distribution and fiber-specific glycolytic and oxidative enzyme activity in skeletal muscle of patients with type 2 diabetes.
OBJECTIVE
We investigated whether alterations of glycolytic and oxidative enzyme capacity in skeletal muscle of patients with type 2 diabetes pertain to specific muscle fibers and are associated with changes in muscle fiber composition.


METHODS
Vastus lateralis muscle was obtained by percutaneous biopsy from 10 patients with type 2 diabetes and 15 age- and BMI-matched healthy volunteers. Using cytophotometry, muscle fiber composition and fiber type-specific glycolytic and oxidative enzyme activities were measured in slow oxidative, fast oxidative glycolytic, and fast glycolytic fibers.


RESULTS
In the whole muscle, oxidative activity was decreased in patients with type 2 diabetes. The slow oxidative fiber fraction was reduced by 16%, whereas the fast glycolytic fiber fraction was increased by 49% in skeletal muscle from the diabetic patients. Both oxidative and glycolytic enzyme activities were significantly increased in fast glycolytic and fast oxidative glycolytic fibers of type 2 diabetic patients. However, the fiber-specific ratio of glycolytic enzyme activity relative to oxidative activity was not different between type 2 diabetic patients and the control subjects. The myofibrillic ATP activity was significantly lower in all fiber types of patients with type 2 diabetes and correlates with glucose infusion rate during the steady state of a euglycemic-hyperinsulinemic clamp and maximal aerobic capacity and negatively with HbA(1c) values.


CONCLUSIONS
Reduced oxidative enzyme activity in muscle of type 2 diabetic patients is most likely due to a reduction in slow oxidative fibers. Increased glycolytic and oxidative enzyme activities in individual muscle fibers are closely related to measures of long-term glycemic control and whole-body insulin sensitivity and could therefore represent a compensatory mechanism of the muscle in function of the altered glucose metabolism.
Institute of Anatomy, University of Leipzig, Germany.
Andreas
A
Oberbach
Yvonne
Y
Bossenz
Stefanie
S
Lehmann
Josef
J
Niebauer
Volker
V
Adams
Ralf
R
Paschke
Michael R
MR
Schön
Matthias
M
Blüher
Karla
K
Punkt
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology*; D005260:Female; D005947:Glucose / Q000378:metabolism; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D006019:Glycolysis; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018656:Muscle Fibers, Fast-Twitch / Q000201:enzymology* / Q000473:pathology; D018657:Muscle Fibers, Slow-Twitch / Q000201:enzymology* / Q000473:pathology; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology; D052097:Quadriceps Muscle / Q000201:enzymology*; D013385:Succinate Dehydrogenase / Q000378:metabolism
D005993:Glycerolphosphate Dehydrogenase; D007770:L-Lactate Dehydrogenase; D013385:Succinate Dehydrogenase; D000251:Adenosine Triphosphatases; D005947:Glucose