Calcium binding protein changes of sarcoplasmic reticulum from rat denervated skeletal muscle.
Two Ca2+ sequestering proteins were studied in fast-twitch (EDL) and slow-twitch (soleus) muscle sarcoplasmic reticulum (SR) as a function of denervation time. Ca2+-ATPase activity measured in SR fractions of normal soleus represented 5% of that measure in SR fractions of normal EDL. Denervation caused a severe decrease in activity only in fast-twitch muscle. Ca2+-ATPase and calsequestrin contents were affected differently by denervation. In EDL SR, Ca2+-ATPase content decreased progressively, whereas in soleus SR, no variation was observed. Calsequestrin showed a slight increase in both muscles as a function of denervation time correlated with increased 45Ca-binding. These results indicate first that Ca2+-ATPase activity in EDL was under neural control, and that because of low Ca2+-ATPase activity and content in slow-twitch muscle no variation could be detected, and secondly that greater calsequestrin content might represent a relative increasing of heavy vesicles or decreasing of light vesicles as a function of denervation time in the whole SR fraction isolated in both types of muscles.
Loirat
M J
MJ
Laboratoire de Physiologie, U.E.R. de Médecine, Nantes, France.
Lucas-Heron
B
B
Ollivier
B
B
Leoty
C
C
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000032:analysis / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008297:Male; D008565:Membrane Proteins / Q000032:analysis; D009121:Muscle Denervation / Q000009:adverse effects*; D009132:Muscles / Q000032:analysis / Q000201:enzymology / Q000294:innervation / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D012519:Sarcoplasmic Reticulum / Q000032:analysis / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure
D002135:Calcium-Binding Proteins; D008565:Membrane Proteins; D000252:Calcium-Transporting ATPases; D002118:Calcium