Erythrocyte flexibility, ATPase activities and Ca efflux in patients with Duchenne muscular dystrophy, myotonic muscular dystrophy and congenital myotonia

Abstract

Erythrocyte flexibility measured by a polycarbonate membrane filtration method showed increased fragility (265 ± 163 Hb mg/l vs. controls 86 ± 72 Hb mg/l; mean ± SD; P < 0.0025) and increased rigidity (123 ± 96 mm Hg vs. 79 ± 19 mm Hg; P < 0.05) in patients with congenital myotonia, while both parameters were normal in patients with Duchenne muscular dystrophy or with myotonic dystrophy. Erythrocyte ghosts obtained from patients with MyD displayed highly significant increases in both (Na + + K +)-ATPase and (Ca 2+ + Mg 2+)-ATPase activities ( P < 0.005) and to a lesser extent in Mg 2+-ATPase activity ( P < 0.05), while no difference was seen between patients with DMD and age-matched controls. The efflux of Ca 2+ was increased from erythrocytes of patients with DMD as compared to age-matched controls (82 ± 2% vs. 70 ± 4%; P < 0.005), while no difference was detected between patients with MyD and age-matched controls.