Mechanisms of Acid-Base Adjustment in Dogfish (Scyliorhinus Stell Aris) Subjected to Long-Term Temperature Acclimation

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Abstract
Specimens of Larger Spotted Dogfish (Scyliorhinus stellaris) were acclimated to a range of temperatures for 22–28 days. The relationships of pH to acclimation temperature in the extracellular space and in three intracellular compartments were essentially the same as previously observed in 24 h acclimated dogfish (Heisler, Weitz & Weitz, 1976). In dogfish subjected to elevated inspired PCO2 during acclimation to low temperature, there was an inversion in the relationship of acclimation temperature to plasma PCO2, and in that to plasma bicarbonate, whereas the relationships to pH values were unchanged. It is concluded that the temperature adaptation of the acid-base parameters is complete after 24 h of temperature acclimation. At least the following mechanisms are involved in the adjustment of pH with changes of temperature: changes of PCO2, changes of buffer pK values, and transmembrane transfer of bicarbonate. Apparently only one of them, the transmembrane transfer of bicarbonate, can be modulated in a sufficient range and is responsible for the final pH adjustment.