Acta Biochimica et Biophysica 11. (1976)

1976 / 4. szám - Kerner, J.-Sándor, A.-Alkonyi, I.: The Effect of Denervation on Carnitine Metabolism in Rat Skeletal Muscle

Acta Biochim. et Biophys. Acad. Sei. Hung. Vol. 11 (4),pp. 239— 243 ( 1976) The Effect of Denervation on Carnitine Metabolism in Rat Skeletal Muscle J. Kerner. A. Sándor, I. Alkonyi Biochemical Institute, University Medical School, Pécs, Hungary (Received February 20, 1976) We investigated the effect of denervation upon the concentration of carnitine, the activity of carnitine palmityltransferase and carnitine acetyltransferase in the “red” soleus and “white” extensor digitorum longus muscles of the rat. Soon after denervation a marked drop in the amount of muscle carnitine was observed, that was more pronounced in the “red” soleus. The activity of both CPT and CAT decreased in both types of muscle, but CPT activi y decreased to a greater extent in the soleus than in the EDL. These data may be indicative of a more impaired fat combustion in the “red” than in the “white” muscle following denervation. Introduction The carnitine-carnitine palmityltransferase system plays an important role in the oxidative degradation of fatty acids because it catalyzes the translocation of activated acyl groups across the mitochondrial acyl-CoA barrier (Fritz, 1968). The carnitine—carnitine acetyltransferase system seems to be involved in buffering the “acetyl pressure” (Pearson, Tubbs, 1967; Childress et al., 1967; Snoswell, Koundakjian, 1972; Alkonyi et al., 1975; Casillas, Erickson, 1975), coupling thereby the rate of fatty acid uptake and activation with the activity of the citric acid cycle (Oram et al., 1973), and ultimately with oxidative phosphorylation. Since fatty acids represent an important substrate for energy metabolism in the muscle, any decrease either in the concentration of carnitine (Engel, Angelini, 1973; Markesbery et al., 1974; Kárpáti et al., 1975; Van Dyke et al., 1975) or in the activity of CPT (Wood et al., 1973; DiMauro, DiMauro, 1973; Bank et al., 1975) and CAT may lead to an impaired energy production owing to a damage of fatty acid oxidation. Since different types of muscle utilize fatty acids for energy production in various proportions, any change in the carnitine—carnitine acyl transferase systems can be expected to affect them to a different extent. Carnitine analyses of muscle biopsies from patients with so-called “carnitine deficient myopathy” refer to muscles considered as mixed types with respect to the fibres Abbreviations : CPT, carnitine palmityltransferase; CAT, carnitine acetyltransferase; EDL, extensor digitorum longus Acta Biochimica et Biophysica Academiae Scientiarum Hungaricae 11, 1976

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