Effects of temperature and salinity on gill Na +-K + ATPase activity in the pupfish, Cyprinodon salinus

Abstract

1. 1. Pupfish ( Cyprinodon salinus) were acclimated to salinities equivalent to fresh-water, 1 2 seawater, seawater and 1 1 2 sea-water at each of three temperatures; 15°, 25° and 30°C. 2. 2. The specific activity of Na +-K + ATPase in gill homogenates from these animals was lowest in 1 2 SW at each temperature and rose significantly in fresh-water- and sea-water-acclimated fish. 3. 3. The specific activity of Na +-K + ATPase in both the fresh-water- and sea-water-acclimated fish increased significantly with decreasing acclimation temperature.