Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow, Russia 119234
Department of Physiology, Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia 117997.
J Exp Biol. 2019 Aug 20;222(Pt 16):jeb202242. doi: 10.1242/jeb.202242.
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 (). 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 ( and ) following winter acclimatization, with cold acclimation having only minor effects. Compared with summer acclimation, the depolarizing L-type calcium current () was larger following winter acclimatization, but again, there was no effect of cold acclimation on Interestingly, the other depolarizing current, , 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.
季节性热重塑（驯化）和实验室热重塑（驯化）会引起变温动物产生不同的生理变化。随着全球温度以越来越快的速度变化，迫切需要了解心脏等关键器官在自然条件下的代偿能力。因此，本研究的目的是直接比较同一广温鱼类，欧洲短角石斑鱼（）中的驯化和驯化反应。我们使用电流和电压钳来测量来自三组鱼的分离心房和心室肌细胞中的离子电流密度：（1）夏季捕获的鱼在 12°C 下保存（“夏季驯化”）; （2）夏季捕获的鱼在 3°C 下保存（“冷驯化”）; 和（3）三月捕获的鱼（“冬季驯化”）。在 7.5°C 的常见测试温度下，与夏季驯化相比，冬季驯化和冷驯化都缩短了动作电位（AP）; 然而，冬季驯化比冷驯化引起更大的缩短。AP 的缩短主要是通过冬季驯化后再极化电流密度（和）的显著增加来实现的，而冷驯化只有较小的影响。与夏季驯化相比，冬季驯化后 L 型钙电流（）更大，但冷驯化对没有影响。有趣的是，在低温下，另一种去极化电流，下降。我们的进一步分析表明，离子电流重塑主要是由于离子通道密度的变化，而不是电流动力学的变化。总之，驯化强烈改变了石斑鱼心脏的电活动，而在相同温度下驯化超过 1.5 个月对心脏的重塑作用非常有限。
