Erythrocyte-ghost Ca2+-stimulated Mg2+-dependent adenosine triphosphatase in Duchenne muscular dystrophy

Abstract

The Ca2+-stimulated Mg2+-dependent ATPase activities (Ca2+-ATPase) of erythrocyteghost membranes from patients with Duchenne muscular dystrophy (DMD) and carriers of DMD were compared with activities of normal controls. The Ca2+-ATPase activity of DMD-patient ghost preparations was found to follow the same pattern of activation by Ca2+ as the control membranes. However, the Ca2+-ATPase activity in DMD and some DMD-carrier preparations was substantially elevated compared with controls. To characterize further the elevated Ca2+-ATPase activity found in DMD-patient ghost membrane preparations, we estimated kinetic parameters using both fine adjustment and weighting methods to analyse our experimental data. It was established that in both DMD and DMD-carrier preparations the increase in Ca2+-ATPase activity was reflected by a significant increase in Vmax rather than by any change in Km. The response of the membrane Ca2+-ATPase activity to changes in temperature was also investigated. In all preparations a break in the Arrhenius plot occurred at 200C, and in DMD and DMD-carrier preparations an elevated Ca2+-ATPase activity was detected at all temperatures. Above 200C the activation energy for all types of preparation was the same, whereas below this temperature there appeared to be an elevated activation in DMD and DMD-carrier preparations compared with normal controls. The concept that a generalized alteration in the physicochemical nature of the membrane lipid domain may be responsible for the many abnormal membrane properties reported in DMD is discussed.Duchenne muscular dystrophy (DMD) is an

Abnormalities of erythrocytes in duchenne muscular dystrophy

“…The fraction of echinocytes in DMD patients was much larger than that in the control group: about 707: echinocytes in D M D patients versus about 4557 in control subjects at 120 hours. In contrast, in phosphate-buffered saline with dextrose but without C a + + , the difference in incidence of echinocytes in the eryrhrocytes from eight DMD patients and from ten controls was small, the ultimate percentage of echinocytes --P D M D ( 7 ) x 10" Figure 4. Although the ATP contents of the erythrocytes of ten DMD patients tended to be high, no differences in the ATP contents of either fresh erythrocytes or stored erythrocytes were observed between DMD patients and control subjects.…”