Inactivation of sarcoplasmic reticulum Ca(2+)-atpase in low-frequency stimulated rat muscle.
Continuous low-frequency stimulation (CLFS) by implanted electrodes for 12-24 h led to a significant (approximately 30%) decrease in the activity of sarcoplasmic reticulum Ca(2+)-ATPase in fast-twitch extensor digitorum longus (EDL) and tibialis anterior (TA) muscles of intact rats. The decline in catalytic activity after 24 h of CLFS was accompanied by an approximately twofold increase in dinitrophenylhydrazine-reactive carbonyl groups of the enzyme. It also correlated with an immunochemically determined 30% decrease in Ca2(+)-ATPase protein. Recovery studies after 12 h of CLFS revealed a relatively slow (48-72 h) re-establishment of normal catalytic activity. These findings suggest that the 30% decline of Ca(2+)-ATPase activity in low-frequency stimulated rat muscle led to an irreversible modification by protein oxidation. The decrease in Ca(2+)-ATPase protein most likely resulted from the degradation of inactive Ca(2+)-ATPase molecules. The relatively slow recovery of Ca(2+)-ATPase activity suggests that de novo synthesis of the enzyme may be necessary to re-attain normal activity.
Matsunaga
S
S
Department of Biology, University of Konstanz, Germany.
Harmon
S
S
Gohlsch
B
B
Ohlendieck
K
K
Pette
D
D
D000818:Animals; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000378:metabolism / Q000494:pharmacology; D004558:Electric Stimulation; D004789:Enzyme Activation / Q000502:physiology; D006834:Hydrazines / Q000378:metabolism; D008297:Male; D008861:Microsomes / Q000201:enzymology; D018656:Muscle Fibers, Fast-Twitch / Q000201:enzymology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D014443:Tyrosine / Q000378:metabolism
D003432:Cross-Linking Reagents; D006834:Hydrazines; C446799:dinitrophenylhydrazine; D014443:Tyrosine; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; D009584:Nitrogen; D002118:Calcium