Thermal acclimation and seasonal acclimatization: a comparative study of cardiac response to prolonged temperature change in shorthorn sculpin

Tatiana S Filatova; Denis V Abramochkin; Holly A Shiels

doi:10.1242/jeb.202242

Thermal acclimation and seasonal acclimatization: a comparative study of cardiac response to prolonged temperature change in shorthorn sculpin

J Exp Biol. 2019 Aug 20;222(Pt 16):jeb202242. doi: 10.1242/jeb.202242.

Authors

Tatiana S Filatova^{1

2}, Denis V Abramochkin^{3

2

4}, Holly A Shiels⁵

Affiliations

¹ Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow, Russia 119234 filatova@mail.bio.msu.ru.
² Department of Physiology, Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia 117997.
³ Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow, Russia 119234.
⁴ Ural Federal University, Mira 19, Ekaterinburg, Russia 620002.
⁵ Faculty of Life Sciences, Core Technology Facility, 46 Grafton Street, University of Manchester, Manchester M13 9NT, UK.

PMID: 31315933
DOI: 10.1242/jeb.202242

Abstract

Seasonal thermal remodelling (acclimatization) and laboratory thermal remodelling (acclimation) can induce different physiological changes in ectothermic animals. As global temperatures are changing at an increasing rate, there is urgency to understand the compensatory abilities of key organs such as the heart to adjust under natural conditions. Thus, the aim of the present study was to directly compare the acclimatization and acclimatory response within a single eurythermal fish species, the European shorthorn sculpin (Myoxocephalus scorpio). We used current- and voltage-clamp to measure ionic current densities in both isolated atrial and ventricular myocytes from three groups of fish: (1) summer-caught fish kept at 12°C ('summer-acclimated'); (2) summer-caught fish kept at 3°C ('cold acclimated'); and (3) fish caught in March ('winter-acclimatized'). At a common test temperature of 7.5°C, action potential (AP) was shortened by both winter acclimatization and cold acclimation compared with summer acclimation; however, winter acclimatization caused a greater shortening than did cold acclimation. Shortening of AP was achieved mostly by a significant increase in repolarizing current density (I_Kr and I_K1) following winter acclimatization, with cold acclimation having only minor effects. Compared with summer acclimation, the depolarizing L-type calcium current (I_Ca) was larger following winter acclimatization, but again, there was no effect of cold acclimation on I_Ca Interestingly, the other depolarizing current, I_Na, was downregulated at low temperatures. Our further analysis shows that ionic current remodelling is primarily due to changes in ion channel density rather than current kinetics. In summary, acclimatization profoundly modified the electrical activity of the sculpin heart while acclimation to the same temperature for >1.5 months produced very limited remodelling effects.

Keywords: Action potential; Electrophysiology; Heart; Hypertrophy; Myoxocephalus scorpio; Thermal remodelling.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Acclimatization*
Action Potentials / physiology*
Animals
Fishes / physiology*
Hot Temperature
Myocytes, Cardiac / physiology*
Seasons
Thermotolerance*