Fiber Type Specific Presence of GIutathione Transferase Isoenzymes in the Rat SkeIetaI Musele Tissue

Abstract

Glutathione transferases (GST) are a group of enzymes, majorly responsible for biochemical detoxification by conjugating glutathione to a set of hydrophobic ligands. The tissue isoenzyme pattern of the enzymes has been well illustrated with their significance of histological localization. But in the cases of muscle tissue, the GST isoenzyme pattern has not yet been clearly studied. In the present experiment, we have carried out an immunohistochemical analysis on the distribution of GST isoenzymes using anti GST-P and anti GST-L antibodies on cardiac, smooth and skeletal muscle tissues. The results showed that the intestinal smooth muscle and cardiac muscles are very weakly immunostained for both anti GST-L and P antibodies. In contrast, major bundles of skeletal muscles were positively responsive to GST-L antibody. Therefore, we compared the expression of GST-L in the muscle tissues of the soleus and plantaris, which were composed dominantly of type I fiber and type II fiber, respectively. The data indicated that only type II fibers in the plantaris muscle tissue were positive to GST-L antibody, which was confirmed by specific ATPase staining. And the soleus muscle, consisting mainly of type I fibers, contains a higher amount of GST-P isoenzyme than the plantaris muscle. Therefore, it can be suggested that the expression of GST isoenzyme can be used as a type-specific marker for the type II fiber of skeletal muscles. And moreover, the differential pattern of GST isoenzymes in those muscle tissues according to fiber types may contribute to explaining the differences in fatigue-sensitivity of muscles to exercise.