Influence of temperature acclimatization on the temperature-dependence and ouabain-sensitivity of goldfish intestinal adenosine triphosphatase

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Abstract
Homogenates of goldfish intestinal mucosa were separated into various fractions by differential centrifugation. Both ATPase and [beta]-glycerophosphatase activities were concentrated mainly in a membrane fraction which sedimented after 1200000 g-min. This membrane ATPase system was activated by Na+ + K+ and inhibited by ouabain. The ouabain -sensitive ATPase activity was high and the ouabain-insensitive activity low in membrane fractions prepared from fish acclimatized previously to 8[degree]. The opposite was true for fish acclimatized to 30[degree] The Arrhenius plots of ouabain-sensitive and ouabain-insensitive ATPase activities, measured from 5[degree]-30[degree], showed discontinuities at incubation temperatures that varied with the previous acclimatization temperature of the fish. Modification of the membrane ATPase system in goldfish intestinal mucosa may regulate Na + transport at different environmental temperatures.