Temperature-dependence of the functional activities of sarcoplasmic reticulum from locust, cockroach and crayfish muscle

1. 1. The temperature-dependence of the Ca 2+ -dependent ATPase and of Ca 2+ -uptake of sarco-plasmic reticulum from the flight muscles of Locusta migratoria, the leg muscles of the cockroach Blaberus fuscus and the abdominal muscles of the crayfish Astacus leptodartylus was studied. 2. 2. The sarcoplasmic reticulum from locust muscle was stable at 45–50°C whereas the sarcoplasmic reticulum from cockroach and crayfish muscle was inactivated at these temperatures. 3. 3. The activation energies of Ca 2+ -uptake by cockroach, locust and crayfish sarcoplasmic reticulum amounted to 50–60 kJ/mol. 4. 4. Sodium deoxycholate and A 23187 shifted the temperature optimum of the Ca 2+ -dependent ATPase towards lower temperatures.