| Abstract: | Palmitate oxidation in rat skeletal muscle was investigated with a suspension of intact isolated cells. M. flexor digitorum brevis was dissociated by a 6 h collagenase treatment to yield single myofibers of which 76% were viable. The contributions of 14CO2 and 14C-labeled acid-soluble intermediates to total oxidation products from palmitate were evaluated. The myofiber suspension exhibited a higher total oxidation rate than the isolated whole muscle, due to improved transport of palmitate to the sarcolemma. Addition of cytoplasmic cofactors L-carnitine, CoASH and ATP did not increase the palmitate oxidation. 14CO2 amounted to about 37% of oxidation products. With [1(-14)C]- and [16(-14)C]palmitate, the oxidation rates were equal. These findings indicate that the cellular integrity was well preserved. The oxidation rates were sharply decreased in fibers with damaged sarcolemmas, and in intact fibers when rotenon and antimycin A were applied. The damaged fibers restored the production of acid-soluble intermediates in the presence of cofactors. The results indicate that suspended skeletal myofibers are an adequate in vitro system for measurements of metabolic activities in the resting muscle. |
