Myotonic muscular dystrophy. Time-dependent alterations in erythrocyte membrane fluidity

The muscle cell membrane may be the site of the basic molecular defect in myotonic muscular dystrophy. Many laboratories, including our own, have suggested that this defect may also be manifested in membrane of extraneural tissue. In previous studies, we found that electron spin resonance results suggested an increased membrane fluidity in erythrocyte membranes that had aged two days in buffer, but we and others could find no such changes in fresh erythrocyte membranes. To investigate these findings further, the results of an initial study of the time course of the membrane fluidity changes in erythrocytes in myotonic muscular dystrophy are given in the present report. They suggest that increased membrane fluidity in myotonic dystrophy is manifested after two days of in vivo ageing and confirm our original findings. These results are discussed in relation to possible effects of metabolic deprivation or of protein-lipid alterations in erythrocytes.