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Updated: Aug 13, 2026
Analysis of Tubular Membrane Networks in Cardiac Myocytes from Atria and Ventricles
Published on: October 15, 2014
Isolation and characterization of transverse tubule from normal and dystrophic mice
Abstract:
I have recently reported the isolation and characterization of sarcoplasmic reticulum from normal and dystrophic mice. These sarcoplasmic reticulum fractions were similar in calcium pump function, calcium release properties, and lipid composition. In this report, I describe the isolation of mouse muscle transverse tubule membranes using a calcium phosphate-loading technique. When the relative purity of normal and dystrophic preparations was considered, transverse tubule from normal and dystrophic mice were similar in calcium-insensitive ATPase activity, cholesterol content, and membrane microviscosity (as estimated by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene); transverse tubule yield from dystrophic muscle, however, was twice that from normal muscle, while sarcoplasmic reticulum yield from these same dystrophic muscles was only 60% that from normal muscle. This result may reflect a difference in the relative quantities of these membranes in situ.
Insights
Dystrophic mouse muscle shows significantly higher transverse tubule yield but lower sarcoplasmic reticulum yield compared to normal muscle. Membrane properties remain similar, suggesting altered membrane quantities in muscular dystrophy.
Area of Science:
- Biochemistry
- Cell Biology
- Muscle Physiology
Background:
- Sarcoplasmic reticulum and transverse tubules are crucial for muscle function.
- Previous studies showed similar sarcoplasmic reticulum function in normal and dystrophic mice.
- Investigating transverse tubule alterations in muscular dystrophy is important.
Purpose of the Study:
- To isolate and characterize mouse muscle transverse tubule membranes.
- To compare transverse tubule properties and yield between normal and dystrophic mice.
- To investigate potential differences in membrane quantity in situ.
Main Methods:
- Isolation of transverse tubule membranes using a calcium phosphate-loading technique.
- Assessment of calcium-insensitive ATPase activity.
- Measurement of cholesterol content and membrane microviscosity using fluorescence polarization (1,6-diphenyl-1,3,5-hexatriene).
Main Results:
- Transverse tubule yield from dystrophic muscle was double that from normal muscle.
- Sarcoplasmic reticulum yield from dystrophic muscle was 60% of that from normal muscle.
- Transverse tubules showed similar calcium-insensitive ATPase activity, cholesterol content, and microviscosity between normal and dystrophic mice.
Conclusions:
- Dystrophic muscle exhibits a higher relative abundance of transverse tubules compared to sarcoplasmic reticulum.
- These findings suggest a potential alteration in the relative quantities of these membrane systems in situ in muscular dystrophy.
- The similar functional and compositional properties of transverse tubules indicate the observed yield difference is likely due to quantity rather than intrinsic changes.
