Temperature and catecholamine effects on metabolism of perfused isolated rabbit muscle

Biceps brachii muscle was isolated from anaesthetized New Zealand rabbits and perfused for 30 min with bovine red cells, while electrically stimulated at 0.1 Hz, 50 V. Temperature was maintained at 34 (physiological temperature of this muscle), 36 or 38 °C in the first experiment (Exp 1). In the second experiment (Exp 2), temperature was maintained at either 34 or 38 °C and the muscle was perfused with 2 ng/ml adrenaline and 10 ng/ml noradrenaline for 5 min during the perfusion. Whatever the temperature, twitch force decreased (P<0.01) during perfusion indicating muscular fatigue. Total turnover rate of "energy-rich" phosphate was higher at 38 °C than at 34 °C (P<0.05) during the first 30 min after the perfusion was stopped in Exp 1 and tended to be higher between 30 and 60 min (P<0.10) in Exp 2. Catecholamine perfusion had no effect on contraction and on muscle metabolism whatever the temperature. Our results show that an increase in temperature of 4 °C above the physiological temperature decreases the resistance of oxygenated rabbit muscle to fatigue. In anoxic muscle, temperature increase accelerates the turnover of "energy-rich" phosphate compounds, which is known to be detrimental to meat quality.