Document Detail

Temperature acclimation modifies Na+ current in fish cardiac myocytes.
MedLine Citation:
PMID:  15235011     Owner:  NLM     Status:  MEDLINE    
The present study was designed to test the hypothesis that temperature acclimation modifies sarcolemmal Na+ current (INa) of the fish cardiac myocytes differently depending on the animal's lifestyle in the cold. Two eurythermal fish species with different physiological strategies for surviving in the cold, a cold-dormant crucian carp (Carassius carassius L.) and a cold-active rainbow trout (Oncorhynchus mykiss), were used in acclimation experiments. The INa of carp and trout were also compared with INa of a cold stenothermal burbot (Lota lota). In accordance with the hypothesis, cold-acclimation decreased the density of INa in crucian carp and increased it in rainbow trout, suggesting depression of impulse conduction in cold-acclimated carp and positive compensation of impulse propagation in cold-acclimated trout. The steady-state activation curve of trout INa was shifted by 6 mV to more negative voltages by cold acclimation, which probably lowers the stimulus threshold for action potentials and further improves cardiac excitability in the cold. In burbot myocytes, the INa density was high and the position of the steady-state activation curve on the voltage axis was even more negative than in trout or carp myocytes, suggesting that the burbot INa is adapted to maintain high excitability and conductivity in the cold. The INa of the burbot heart differed from those of carp and trout in causing four times larger charge influx per excitation, which suggests that INa may also have a significant role in cardiac excitation-contraction coupling of the burbot heart. In summary, INa of fish cardiac myocytes shows thermal plasticity that is different in several respects in cold-dormant and cold-active species and thus has a physiologically meaningful role in supporting the variable life styles and habitat conditions of each species.
Jaakko Haverinen; Matti Vornanen
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  207     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2004 Jul 
Date Detail:
Created Date:  2004-07-05     Completed Date:  2004-10-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  2823-33     Citation Subset:  IM    
University of Joensuu, Department of Biology, PO Box 111, 80101 Joensuu, Finland.
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MeSH Terms
Acclimatization / physiology*
Analysis of Variance
Biological Transport, Active / physiology
Carps / metabolism,  physiology*
Ion Transport
Myocytes, Cardiac / metabolism*
Oncorhynchus mykiss / metabolism,  physiology*
Patch-Clamp Techniques
Sodium / metabolism*
Reg. No./Substance:

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