cAMP levels in fast- and slow-twitch skeletal muscle after an acute bout of aerobic exercise.
The present study examined whether exercise duration was associated with elevated and/or sustained elevations of postexercise adenosine 3',5'-cyclic monophosphate (cAMP) by measuring cAMP levels in skeletal muscle for up to 4 h after acute exercise bouts of durations that are known to either produce (60 min) or not produce (10 min) mitochondrial proliferation after chronic training. Treadmill-acclimatized, but untrained, rats were run at 22 m/min for 0 (control), 10, or 60 min and were killed at various postexercise (0, 0.5, 1, 2, and 4 h) time points. Fast-twitch white and red (quadriceps) and slow-twitch (soleus) muscles were quickly excised, frozen in liquid nitrogen, and assayed for cAMP with a commercial kit. Unexpectedly, cAMP contents in all three muscles were similar to control (nonexercise) at most (21 of 30) time points after a single 10- or 60-min run. Values at 9 of 30 time points were significantly different from control (P < 0.05); i.e., 3 time points were significantly higher than control and 6 were significantly less than control. These data suggest that the cAMP concentration of untrained skeletal muscle after a single bout of endurance-type exercise is not, by itself, associated with exercise duration.
Department of Physiology and Cell Biology, University of Texas Medical School, Houston 77225.
A
A
Sheldon
F W
FW
Booth
C R
CR
Kirby
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D000431:Ethanol; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008722:Methods; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism*; D009994:Osmolar Concentration; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010805:Physical Conditioning, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014238:Trichloroacetic Acid
D010726:Phosphodiesterase Inhibitors; D000431:Ethanol; D014238:Trichloroacetic Acid; D000242:Cyclic AMP; D007545:Isoproterenol