Section 14
Chapter 13,079

Altered fiber distribution and fiber-specific glycolytic and oxidative enzyme activity in skeletal muscle of patients with type 2 diabetes

Oberbach, A.; Bossenz, Y.; Lehmann, S.; Niebauer, J.; Adams, V.; Paschke, R.; Schön, M.R.; Blüher, M.; Punkt, K.

Diabetes Care 29(4): 895-900


ISSN/ISBN: 0149-5992
PMID: 16567834
DOI: 10.2337/diacare.29.04.06.dc05-1854
Accession: 013078140

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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. RESEARCH DESIGN AND 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[subscript 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.

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