Myofibrillar ATPase activity in the carp Cyprinus carpio: interactions between starvation and environmental temperature.

The myofibrillar ATPase activity of the epaxial white muscle was measured in carp Cyprinus carpio L. acclimated to 10 degrees C or 28 degrees C. As previously reported, cold acclimation was associated with an increase in the ATPase specific activity and a decrease in the thermostability. The water content of the white muscle was significantly higher in cold-acclimated fish than in warm-acclimated fish (P less than 0.002). Starvation for 10 weeks resulted in a significant increase in the white muscle water content of both warm- and cold-acclimated fish (P less than 0.002). When carp were starved, the ability of the myofibrillar ATPase to show thermal compensation disappeared. Previously acclimated fish, when starved, showed steady alterations of the myofibrillar ATPase activity to a level mid-way between the acclimated extremes. Refeeding resulted in a gradual return to the normal acclimated level.