Towards a valid preparation for the in vitro study of energy metabolism in fish muscles

Slices of lateral red muscle and isolated intact Musculus protractor hyoidei of goldfish were examined for their suitability as model systems for the in vitro study of muscular energy metabolism. Slicing of red muscle causes a strong breakdown of ATP and creatine phosphate and a lowering of the adenylate energy charge. Furthermore, slices do not recover when incubated in an oxygenated balanced salt solution, but show a continuous depletion of direct energy reserves. In contrast with red muscle slices, the Musculus protractor hyoidei can be isolated in an intact state, as shown by constancy of creatine phosphate and adenylate levels and stability of the adenylate energy charge during incubation. Therefore, isolated M. protractor hyoidei seems to be promising as a model system for the in vitro study of muscular energy metabolism.