Physical state abnormality of erythrocyte membrane in myotonic dystrophy: a spin label study

Biophysical abnormalities of the erythrocyte membrane in muscular dystrophies have been described by numerous authors. This work presents the results we have obtained on 23 subjects suffering from myotonic muscular dystrophy (MyD, Steinert disease) by the spin label method. Two types of fatty acid spin labels were used: 5-nitroxide stearic acid (5NS) and 16-nitroxide stearic acid (16NS) which probe the membranes respectively near their polar heads and in their hydrophobic core. We measured the classical order parameter, the saturation behaviour of the electron paramagnetic resonance signal, and the label apparent rotation correlation time as a function of the temperature, on fresh and in vitro stored red blood cells. With the 5NS label, no differences were found between controls and patients. With the 16NS label, a highly significant variation in the thermic behaviour of the membrane is observed in its hydrophobic and fluid core. This last result may suggest some similarities between the red blood cell membranes of adult MyD's and healthy children.