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Time course of changes in plasma membrane permeability in the dystrophin-deficient mdx mouse
A McArdle1, R H Edwards, M J Jackson
1Department of Medicine, University of Liverpool, United Kingdom.
Abstract:
Control C57Bl/10 and mutant, dystrophin-deficient mdx mice of different ages were used to study the permeability of the plasma membrane to cytosolic components, to a vital stain (procion orange) and to extracellular 45calcium. Prenecrotic, 14 +/- 2-day-old mdx mice had normal serum activities of creatine kinase (CK) and pyruvate kinase (PK). Muscles from these animals also had no increased permeability to procion orange or extracellular 45calcium. Serum activities of CK and PK had risen acutely in the 21-day-old mdx mouse compared with control and remained elevated up to 6 months of age. The influx of procion orange and 45calcium content were abnormally elevated in the 40 +/- 4-day-old mdx mouse. These data provide no evidence for an increase in muscle plasma membrane permeability as a primary pathogenic effect of a lack of dystrophin, but results suggest that some factor expressed or de-expressed during mouse development may be necessary for the full expression of the dystrophic process.
Insights
Duchenne muscular dystrophy research shows that the lack of dystrophin in mdx mice does not immediately increase muscle membrane permeability. Other developmental factors are likely needed for full disease progression.
Area of Science:
- Biochemistry
- Cell Biology
- Genetics
Background:
- Duchenne muscular dystrophy is a genetic disorder characterized by progressive muscle degeneration.
- Dystrophin deficiency in mdx mice is a common model for studying this disease.
- Understanding the early pathogenic mechanisms is crucial for developing effective therapies.
Purpose of the Study:
- To investigate the role of dystrophin deficiency in muscle plasma membrane permeability in mdx mice.
- To determine the temporal relationship between dystrophin absence and membrane defects.
- To explore potential developmental factors influencing muscular dystrophy.
Main Methods:
- Comparison of control C57Bl/10 and dystrophin-deficient mdx mice across various age groups.
- Assessment of plasma membrane permeability using cytosolic components, procion orange vital stain, and extracellular 45calcium.
- Measurement of serum creatine kinase (CK) and pyruvate kinase (PK) activities.
Main Results:
- Pre-necrotic mdx mice (14 days) exhibited normal serum CK/PK levels and no increased membrane permeability.
- Serum CK/PK levels acutely increased in 21-day-old mdx mice and remained elevated up to 6 months.
- Abnormal influx of procion orange and 45calcium was observed in 40-day-old mdx mice.
Conclusions:
- The absence of dystrophin alone does not appear to be the primary cause of increased muscle plasma membrane permeability.
- Results suggest that developmental factors influence the full manifestation of the dystrophic process in mdx mice.
- Further research is needed to identify these developmental factors and their role in muscular dystrophy.