Abstract
The properties of the sarcoplasmic reticulum membranes isolated from slow-twitch type Isoleus and fast-twitch type II psoas muscles of control and thyroxine treated rabbits were comparatively studied. Membrane yield, maximal calcium storing capacity, ATP-supported calcium uptake, calcium-dependent ATPase activity and calcium-dependent phosphoproteinformation were found to be 3—10 fold higher in psoas than in soleus preparations. Membrane yield, calciumdependent ATPase activity, ATP-supported calcium transport and calcium-dependent phosphoprotein are at least twice enhanced in the membranes from soleus muscles of animals treated for 14—21 days with thyroxine. The corresponding capacities of the membranes from psoas muscles are not further augmented by the same thyroxine treatment. The maximal calcium storing capacity of the psoas membranes is their sole specific property which is significantly increased. The changes in the properties ofthe soleus muscles' sarcoplasmic reticulum membranes are engendered by an increase from 5 to 30—50% in the number of type II fibres. Since the calcium transporting properties of the sarcoplasmic reticulum membranes from type II fibres qualitatively differ from those of type I fibres, thyroxine does not only affect quantitative but also qualitative parametersofthe muscles' sarcoplasmic reticulum membrane system.
Original language | English (US) |
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Pages (from-to) | 726-734 |
Number of pages | 9 |
Journal | Zeitschrift fur Naturforschung - Section C Journal of Biosciences |
Volume | 40 |
Issue number | 9-10 |
DOIs | |
State | Published - Aug 1 1985 |
Externally published | Yes |
Keywords
- Fast and Slow Twitch Muscles
- Sarcoplasmic Reticulum
- Thyroxine
ASJC Scopus subject areas
- General Biochemistry, Genetics and Molecular Biology