A gated 31P-n.m.r. study of bioenergetic recovery in rat skeletal muscle after tetanic contraction.
1. Gated 31P-n.m.r. spectra were obtained from the ankle flexor muscles of the rat at various times after 3 s isometric tetanic contraction. This allowed the time course of changes in phosphocreatine (PCr), Pi and free ADP concentrations and intracellular pH to be monitored in skeletal muscle in vivo with 1 s time resolution. 2. ATP concentration did not change significantly, either during the recovery from a 3 s tetanus or during the overall protocol. 3. The calculated rate of recovery of ADP towards pre-stimulation levels was very rapid (t1/2 less than 5 s). The rate of Pi disappearance (t1/2 = 14 s) was more rapid than the rate of PCr synthesis (t1/2 = 24 s), resulting in a significant transient decrease in n.m.r.-visible PCr + Pi between 25 and 45 s after tetanic contraction. 4. The rates of PCr, Pi and ADP recovery are higher than those previously reported for recovery from steady-state exercise in humans or twitch isometric contraction in animals.
Challiss
R A
RA
Department of Biochemistry, University of Oxford, U.K.
Blackledge
M J
MJ
Shoubridge
E A
EA
Radda
G K
GK
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004734:Energy Metabolism; D006863:Hydrogen-Ion Concentration; D007537:Isometric Contraction; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate