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首页> 外文期刊>Journal of Comparative Physiology, B. Biochemical, Systemic, and Environmental Physiology >Temperature-dependence of L-type Ca2+ current in ventricular cardiomyocytes of the Alaska blackfish (Dallia pectoralis)
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Temperature-dependence of L-type Ca2+ current in ventricular cardiomyocytes of the Alaska blackfish (Dallia pectoralis)

机译：阿拉斯加黑鱼（Dallia pectoralis）心室心肌细胞中L型Ca2 +电流的温度依赖性

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摘要

To lend insight into the overwintering strategy of the Alaska blackfish (Dallia pectoralis), we acclimated fish to 15 or 5 A degrees C and then utilized whole-cell patch clamp to characterize the effects of thermal acclimation and acute temperature change on the density and kinetics of ventricular L-type Ca2+ current (I (Ca)). Peak I (Ca) density at 5 A degrees C (-1.1 +/- A 0.1 pA pF(-1)) was 1/8th that at 15 A degrees C (-8.8 +/- A 0.6 pA pF(-1)). However, alterations of the Ca2+- and voltage-dependent inactivation properties of L-type Ca2+ channels partially compensated against the decrease. The time constant tau (tau) for the kinetics of inactivation of I (Ca) was similar to 4.5 times greater at 5 A degrees C than at 15 A degrees C, and the voltage for half-maximal inactivation was shifted from -23.3 +/- A 1.0 mV at 15 A degrees C to -19.8 +/- A 1.2 mV at 5 A degrees C. These modifications increase the open probability of the channel and culminate in an approximate doubling of the L-type Ca2+ window current, which contributes to approximately 15 % of the maximal Ca2+ conductance at 5 A degrees C. Consequently, the charge density of I (Ca) (Q (Ca)) and the total Ca2+ transferred through the L-type Ca2+ channels (Delta[Ca2+]) were not as severely reduced at 5 A degrees C as compared to peak I (Ca) density. In combination, the results suggest that while the Alaska blackfish substantially down-regulates I (Ca) with acclimation to low temperature, there is sufficient compensation in the kinetics of the L-type Ca2+ channel to support the level of cardiac performance required for the fish to remain active throughout the winter.
机译：为了深入了解阿拉斯加黑鱼（Dallia pectoralis）的越冬策略，我们将鱼适应了15或5 A摄氏度的温度，然后利用全细胞膜片钳来表征热适应和急性温度变化对密度和动力学的影响心室L型Ca2 +电流（I（Ca））。在5 A摄氏度（-1.1 +/- A 0.1 pA pF（-1））的峰I（Ca）密度是在15 A摄氏度（-8.8 +/- A 0.6 pA pF（-1）的峰密度的1/8 ）。但是，L型Ca2 +通道的Ca2 +-和电压依赖性失活特性的改变部分补偿了这种降低。 I（Ca）失活动力学的时间常数tau（tau）类似于在5 A摄氏度下比在15 A摄氏度下大4.5倍，半最大失活电压从-23.3 + / -在15 A摄氏度时为1.0 mV至在5 A摄氏度时为-19.8 +/- +/- 1.2 mV。这些修改增加了通道的打开概率，最终使L型Ca2 +窗口电流近似加倍，这有助于约为5 A时最大Ca2 +电导的15％。因此，I（Ca）（Q（Ca））的电荷密度和通过L型Ca2 +通道转移的总Ca2 +（Delta [Ca2 +]）为与峰值I（Ca）密度相比，在5 A摄氏度下的降低幅度不那么严重。综合来看，结果表明，尽管阿拉斯加黑鱼在适应低温后会大幅下调I（Ca），但L型Ca2 +通道的动力学有足够的补偿来支持鱼所需的心脏功能水平在整个冬季保持活跃。

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