Death of dystrophin-deficient muscle purportedly results from increases in [Ca] in that cause
the activation of calpains. We have tested whether calpains play a role in this process by
assaying for changes in calpain concentration and activation in peak necrotic mdx mice (4
weeks of age) and in completely regenerated mdx mice (14 weeks of age). Biochemical
fractionation and immunoblotting with epitope-specific antisera allowed measurement of the
concentrations of m-and μ-calpains and the extent of autoproteolytic modification. Our …