Effects of seasonal acclimatization on thermal tolerance of inward currents in roach (Rutilus rutilus) cardiac myocytes

@article{Badr2017EffectsOS,
  title={Effects of seasonal acclimatization on thermal tolerance of inward currents in roach (Rutilus rutilus) cardiac myocytes},
  author={Ahmed Badr and Hanna Korajoki and El-Sabry Abu-Amra and M. F. El-Sayed and Matti Vornanen},
  journal={Journal of Comparative Physiology B},
  year={2017},
  volume={188},
  pages={255-269}
}
To test the hypothesis of temperature-dependent deterioration of electrical excitability (TDEE) (Vornanen, J Exp Biol 219:1941–1952, 2016), the role of sodium (INa) and calcium (ICa) currents in heat tolerance of cardiac excitability was examined in a eurythermic fish, the roach (Rutilus rutilus). Densities of cardiac ICa and INa and their acute heat tolerance were measured in winter-acclimatized (WiR) and summer-acclimatized (SuR) fish maintained in the laboratory at 4 ± 1 and 18 ± 1 °C… 
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Findings show that at critically high temperatures AV block causes ventricular bradycardia which is an outcome from the increased excitation threshold of the ventricle due to changes in passive (resting ion leak) and active (inward charge movement) electrical properties of ventricular myocytes.
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TLDR
Results show that at critically high temperatures AV block causes ventricular bradycardia which is an outcome from the increased excitation threshold of the ventricle due to changes in passive (resting ion leak) and active (inward charge movement) electrical properties of ventricular myocytes.
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  • M. Vornanen
  • Chemistry, Medicine
    Journal of Experimental Biology
  • 2020
TLDR
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Reduced ventricular excitability causes atrioventricular block and depression of heart rate in fish at critically high temperatures
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TLDR
High baseline cortisol levels in subordinate trout result in lowered thermal tolerance, but 5 d of social stress did not greatly affect cardiac structure and function, as previously reported for cortisol-treated rainbow trout.

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