Effect of aerobic training on 99mTc-methoxy isobutyl isonitrile (99mTc-sestamibi) uptake by myocardium and skeletal muscle: implication for noninvasive assessment of muscle metabolic profile.
OBJECTIVE
The effect of long-term endurance training on skeletal muscle and myocardial uptake of (99m)Tc-sestamibi, a radiopharmaceutical accumulating in the mitochondria, was investigated.


METHODS
Twenty-six Wistar rats were divided into a trained (5 days week(-1) endurance running for 14 weeks) and an untrained group. On completion of training, (99m)Tc-sestamibi was administered and, 2 h post-injection, the myocardium and the soleus, extensor digitorum longus (EDL) and medial gastrocnemius (MG) muscles were removed for the measurement of cytochrome c oxidase (CCO) activity and (99m)Tc-sestamibi uptake. Tissue (99m)Tc-sestamibi kinetics was preliminarily studied in 16 other rats for up to 2 h post-injection.


RESULTS
Two hours post-injection (99m)Tc-sestamibi uptake was either stable (myocardium) or still rising (skeletal muscles). Both CCO activity and (99m)Tc-sestamibi uptake decreased in the same order (myocardium, soleus, EDL, MG) in the tissues examined. The CCO activity of the EDL and MG muscles was higher (P < 0.05) in the trained compared to the untrained group. (99m)Tc-sestamibi uptake in the soleus and EDL muscles was higher (P < 0.05) in the trained compared to the untrained rats, whereas the difference in MG was marginally significant (P = 0.06) in favour of the trained group.


CONCLUSIONS
Long-term endurance training, resulting in elevated skeletal muscle CCO activity, is also associated with a similar increase in (99m)Tc-sestamibi uptake. This finding suggests that (99m)Tc-sestamibi could be used in imaging assessment of skeletal muscle metabolism with possible applications in both clinical and sports medicine settings.
Kyparos
D
D
Laboratory of Physiology, Department of Physical Education and Sports Science, Aristotle University of Thessaloniki, Thessaloniki, Greece.
Arsos
G
G
Kyparos
A
A
Georga
S
S
Petridou
A
A
Sotiriadou
S
S
Mougios
V
V
Matziari
C
C
D000818:Animals; D003576:Electron Transport Complex IV / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D019275:Radiopharmaceuticals; D051381:Rats; D017208:Rats, Wistar; D017256:Technetium Tc 99m Sestamibi
D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi; D003576:Electron Transport Complex IV