Resting Metabolism and Myofibrillar Mg2+-ATPase Activity of Carp Acclimated to Different Temperatures.

Resting metabolism (RM) and myofibrillar Mg2+-ATPase activity at various temperatures were studied using carp reared at 10°C (group L) and 25.5°C (group H). The level of RM was higher in group L than group H at 19.5°C. On the basis of this result, it was considered that a positive thermal compensation occurred in group L. Myofibrillar Mg2+-ATPase activities in the presence and absence of Ca2+ were greater in group L than group H at 5°C to 30°C. The temperature dependences of RM and myofibrillar Mg2+-ATPase in the presence of Ca2+ were greater in group L than group H in a measuring temperature range below the rearing temperature, and a significant positive correlation was found in the relationship between these temperature dependences. This result suggested the RM and myofibrillar Mg2+-ATPase activity in the presence of Ca2+ might be related.The levels of Ca-sensitivity tended to be lower in group L than group H at reaction temperatures of 5 to 30°C, and were high at rearing temperature in groups L and H. The results suggested that Ca-regulation of myofibrillar ATPase was fully displayed at habitat temperature in carp acclimated to different temperatures.