摘要 : The metabolic response and ultrastructure of muscle was investigated in horses performing intense exercise at different ambient temperatures. Four Standardbred geldings exercised on a treadmill, at an intensive trot of 2600 m on 2... 展开 The metabolic response and ultrastructure of muscle was investigated in horses performing intense exercise at different ambient temperatures. Four Standardbred geldings exercised on a treadmill, at an intensive trot of 2600 m on 2 different occasions, either at a high ambient temperature of 35deg C or at a temperature of 20deg C. The horses had a warm-up period of 23.5 min of below maximum exercise, followed by 2 h of box rest before the intensive exercise. Muscle biopsy data of adenine nucleotides, creatine phosphate, lactate and glycogen concentrations measured before the warm-up period were similar to those measured before the period of intensive exercise. Muscle lactate concentrations did not differ between the 2 temperatures, but increased significantly after intense exercise to levels of 34.7±8.3 mmol/kg at 20deg C, and to 41.7±12.5 mmol/kg at 35deg C. Muscle glycogen and creatine phosphate concentrations did not differ between the 2 ambient temperatures, but decreased significantly by 122±82 mmol/kg and 25.2±17.4 mmol/kg, respectively, after the intensive exercise. No changes were seen in adenosine triphosphate, adenosine diphosphate and adenosine monophosphate concentrations. The muscle biopsies were investigated by electron microscopy, and showed no marked changes in the ultrastructure of the muscle due to exercise at the 2 different ambient temperatures. It is concluded that there were no great changes in the muscle metabolic response or in the ultrastructure of the muscle when the horses performed intense exercise at 35deg C compared with 20deg C. 收起