Effect of post-mortem storage temperatures on isometric tension, pH, ATP, glycogen and glucose-6-phosphate for selected bovine muscles.

Relationships between isometric tension development and pH, ATP, glucose-6-phosphate and glycogen levels as a function of post-mortem storage temperature were examined for three bovine muscles. Tension responses in the range of 5-37°C were similar for B. femoris, Vastus lateralis and outer M. semitendinosis. At 0°C, the three muscles developed considerably higher tension than at 5°C. Cold shortening developed only in the outer M. semitendinosis strips at 0°C. At low temperatures the drop in pH lagged compared to the decline in ATP and glycogen and maximum tension was attained several hours after ultimate pH and minimum levels of ATP and glycogen were reached. Glucose-6-phosphate was found to accumulate rapidly at 0°C in both outer M. semitendinosis and B. femoris, being more pronounced in the latter muscle. The responses of glucose-6-phosphate levels suggest that the relative activities of glycolytic enzymes in muscle stored at 0°C are altered compared to those in muscle stored at higher temperatures.