scholarly journals Characteristics of sarcoplasmic reticulum from normal and denervated rat skeletal muscle

1981 ◽  
Vol 200 (1) ◽  
pp. 11-15 ◽  
Author(s):  
G N Palexas ◽  
N Savage ◽  
H Isaacs
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Calcium Transport ◽  
Membrane Structure ◽  
Calcium Content ◽  
Heterogeneous Population ◽  
Rat Skeletal Muscle ◽  
Vesicle Size ◽  
Dependent Atpase

Denervation of rat skeletal muscle produces after 14 days a decrease in Ca2+ uptake of a heterogeneous population of sarcoplasmic-reticulum vesicles, when measured in the presence of oxalate. The Mg2+-dependent ATPase (Ca2+-independent) activity increased after the same period and the Ca2+ + Mg2+-dependent ATPase activity decreased. Concomitant with these changes, there was an increase in vesicle size and calcium content. The observations are discussed in terms of changes in altered membrane structure, manifested in the shift of the equilibrium of the ATPase from an enzyme involved in calcium transport to a phosphoenzyme giving rise to an increase in the Mg2+-dependent ATPase activity.

scholarly journals The effect of dantrolene on skeletal-muscle sarcoplasmic-reticulum function in malignant hyperpyrexia in pigs

1983 ◽  
Vol 212 (2) ◽  
pp. 399-405 ◽  
Author(s):  
M D White ◽  
J G Collins ◽  
M A Denborough
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Muscle Relaxant ◽  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Polyacrylamide Gel ◽  
Malignant Hyperpyrexia ◽  
Dependent Atpase ◽  
Sarcoplasmic Reticulum Membrane

The effect of the muscle relaxant dantrolene on isolated sarcoplasmic reticulum was studied in control and malignant-hyperpyrexia-susceptible Landrace pigs. The membranes prepared from both sources showed similar Ca2+-dependent ATPase activities, had comparable phospholipid/protein ratios, and their sodium dodecyl sulphate/polyacrylamide-gel patterns were indistinguishable. Membranes from both sources appeared to bind similar amounts of dantrolene. The drug did not stimulate Ca2+-dependent ATPase activity in preparations from either source. The rates of Ca2+ exchange and Ca2+ efflux appeared to be similar in sarcoplasmic reticulum of control and malignant-hyperpyrexia-susceptible pigs. Dantrolene did not affect either the rates or the amount of Ca2+ lost from the vesicles. These results suggest that dantrolene does not directly affect the movement of Ca2+ across the sarcoplasmic-reticulum membrane.

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