Biochemical Abnormalities of the Sarcoplasmic Reticulum in Muscular Dystrophy

Abstract

Calcium-uptake and ATPase studies carried out on fragmented sarcoplasmic reticulum from muscle of patients with Duchenne dystrophy showed low initial and total calcium uptake, low ATPase activity and normal efficiency, without any relation to the stage of the disease. In myotonic dystrophy, on the other hand, high initial and normal total calcium uptake and normal or higher than normal efficiencies were found. The data suggest early involvement of both fiber types in Duchenne dystrophy and primary involvement of red fibers in myotonic dystrophy. Actomyosin abnormalities found in three cases of Duchenne dystrophy indicate involvement of the contractile apparatus in the later stages of the disease. The only clinical-biochemical correlation observed in this study was the relation of the ATPase activity of the fragmented sarcoplasmic reticulum to the onset of Duchenne dystrophy.