(99m)Tc-sestamibi uptake in rat skeletal muscle and heart: physiological determinants and correlations.

Physiological Research
G ArsosC Karakatsanis

Abstract

The lipophilic cationic radiotracer (99m)Tc-sestamibi, known to be concentrated within mitochondria, is widely used for myocardial perfusion and to a lesser extent for muscle metabolism imaging. However, the exact distribution pattern in skeletal muscle has not been yet studied in detail. The present study aims to investigate the (99m)Tc-sestamibi uptake in rat skeletal muscle and myocardium in relation to their metabolic characteristics. (99m)Tc-sestamibi was i.v. administered in twenty adult male Wistar rats and uptake, as percent of injected dose per tissue gram (%ID/g), in the myocardium, soleus, extensor digitorum longus and gastrocnemius muscles was assessed 2 h after the injection. Muscle uptake was also correlated with myocardial uptake, muscle weight and body weight. Skeletal muscle (99m)Tc-sestamibi uptake was a small (9-16 %) fraction of that found in myocardium (1.71+/-0.63 %ID/g). Among the three hindlimb muscles considered, the slow-oxidative soleus muscle showed the highest uptake (0.28+/-0.16 %ID/g). Metabolically diverse parts of the gastrocnemius muscle showed different uptake. Skeletal muscle uptake was positively correlated with myocardial uptake and both were negatively correlated with tissue and body weigh...Continue Reading

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