Autor: E. Aho, M. Vornamen
Rok vydání: 1997
Předmět:
Zdroj: Fish Physiology and Biochemistry. 16:355-364
ISSN: 0920-1742
DOI: 10.1023/a:1007727024877
Popis: The effects of seasonal acclimatization, thermal acclimation and anoxic exposure on total cation-activated ATPase and sarcolemmal Na-K-ATPase activities of crucian carp heart were measured. The total cation-activated ATPase showed a positive correlation with environmental temperature: activity was highest in mid summer and lower in early spring and late autumn. The decline of total ATPase activity during cold seasons suggests that energy consumption of the heart is reduced during the anoxic winter period by depression of ATP utilization rate. In contrast to the total ATPase activity, the activity of sarcolemmal Na-K-ATPase did not correlate strongly with environmental temperature but remained relatively constan during most of the study period. However, in late autumn when oxygen content of water is low, a prominent decline in Na-K-ATPase activity was noted. The latter finding suggests that the activity of Na-K-pump of the cardiac sarcolemma is unaffected by seasonal temperature changes but is depressed by hypoxic exposure. In accordance with this short-term anoxia (100 h) in laboratory conditions reduced Na-K-ATPase or pNPPase activities of cardiac homogenates while long-term thermal acclimation (>4 weeks) was ineffective in this respect. The present findings suggest that cation-activated ATPases of crucian carp heart are downregulated during winter, and part of this reduction is due to anoxic depression of sarcolemmal Na-K-ATPase.
Databáze: OpenAIRE