FASTING INCREASES THE EXTENT OF MUSCLE NECROSIS IN THE MDX MOUSE

1. The effects of fasting for 48h were investigated in C57BL/10 (wild type) and age-matched C57BL/10 dystrophin-deficient (mdx) mice, 2. Fas ting resulted in an increased percentage of in muscles from the hindli mb and of mdx mice, The percentage of necrotic fibres of forelimb and chest muscles of mdx mice was unaltered by fasting. In wild-type mice, very few necrotic fibres were observed after fasting, 3. The necrotic changes in fasted mdx muscle were not accompanied by altered energy s tatus as evaluated by muscle ATP and phosphocreatine concentrations, 4 . A significantly decreased rectal temperature was but not in wild-typ e mice after observed in mdx fasting, 5. Fasting would normally be exp ected to cause a reduction in muscle fibre size, The high prevalence o f necrosis in fasted mdx mice is therefore an unusual response that ma y be related to disturbance of the mechanisms which, in the fed state, compensate for the dystrophin deficiency in these animals.