Contractile properties of goldfish fin muscles following temperature acclimation

Abstract

1. Parameters of the isometric twitch were measured for the pectoral fin adductor muscles of goldfishCarassius auratus acclimated to 10°C or 28°C. Contractile parameters and myofibrillar ATPase activities were measured at a range of temperatures. The muscle fibre composition was measured for transverse sections of pectoral fin adductor muscles from goldfish acclimated to 10°C or 28°C. 2. Cold acclimation was associated with an increase in the proportion of oxidative fibre types. Muscles from cold acclimated fish had an average of 23% more red and pink fibres than muscles from warm acclimated fish. 3. Cold acclimated fin muscles also possessed a significantly higher myofibrillar ATPase activity than warm acclimated fin muscles. This difference was greatest at lower measurement temperatures. 4. Muscles from cold acclimated fish were able to maintain quicker rates of contraction and relaxation at low environmental temperatures, as shown by the possession of significantly shorter response times. 5. The temperature dependence (Q10) of the isometric twitch contratile parameters for fin muscle from warm or cold acclimated goldfish was similar over the temperature range 20–30°C. However, over the temperature range 6–15°C fin muscles from warm acclimated goldfish possessed consistently higher Q10's.