Cytophotometry of post mortem glycogenolysis in quiescent bovine muscle fibres in relation to temperature, succinate dehydrogenase activity and adenosine triphosphatase activity

Summary Immediatepost mortem samples of sternomandibularis muscles from six steers were maintained with a minimum of intrinsic activity at approximately 40°C or allowed to cool to approximately 22°C. Samples were frozen in liquid nitrogen at 0, 2, 4 and 6hpost mortem and serial transverse sections were stained by the periodic acid-Schiff (PAS) reaction for glycogen or reacted for adenosine triphosphatase (ATPase) or succinate dehydrogenase. Individual fibres were mapped and categorized from their ATPase and succinate dehydrogenase activity using a projecting microscope. The absorbance of PAS-stained glycogen in individual fibres was measured with a microscope photometer at 570 and 601 nm with a correction for distributional error. Overall, thepost mortem decline in absorbance was approximately twice as fast in body temperature samples relative to room temperature samples. Transientpost mortem increases in absorbance were detected in some situations, particularly in fibres with strong ATPase activity from room temperature samples. In fibres with strong ATPase activity, the rate of decline in absorbance increased progressivelypost mortem. Fibres with weak ATPase mostly had a lower initialpost mortem absorbance and were generally the first to become PAS-negative.