Sarcoplasmic reticulum ATPase activity in type I and II skeletal muscle fibres of chronic heart failure patients

BackgroundReduced exercise tolerance and muscle weakness are present in patients with CHF. Altered metabolism, histology and function in skeletal muscle of patients with CHF have been reported. The sarcoplasmic reticulum (SR) has control of Ca++ release and uptake required for contraction and relaxation, respectively, and uses a considerable amount of energy. Little is known about SR alterations in CHF. We determined sarcoplasmic reticulum adenosine triphosphatase (SR ATPase) activity in different types of skeletal muscle fibres of CHF patients.MethodsSR ATPase activity, succinate dehydrogenase (SDH) activity and myofibrillar adenosine triphosphatase (M ATPase) activity in single fibres of the vastus lateralis muscle in 16 CHF patients and 5 controls was determined using quantitative enzyme histochemistry.ResultsSR ATPase activity of type II skeletal muscle fibers was significantly higher compared to type I fibres. SR ATPase activity in type II skeletal muscle fibres of CHF patients was higher than in control subjects.ConclusionIncreased skeletal muscle SR ATPase activity contributes to reduced exercise tolerance in CHF patients.