Glitsch H G, Pusch H
Pflugers Arch. 1984 Sep;402(1):109-15. doi: 10.1007/BF00584839.
The temperature dependence of cardiac active Na transport is studied in voltage clamped sheep Purkinje fibres by means of simultaneous measurements of the membrane current (I) and the intracellular Na activity (alpha iNa). During activation of the Na pump a transient outward current (delta I) and alpha iNa decline exponentially with an identical time constant (tau). The transient outward current and the decline in alpha iNa are blocked by 10(-4) M dihydroouabain (DHO). Lowering the temperature from 42 degrees C to 17 degrees C prolongs tau. The electrogenic fraction (e.f.) of the active Na efflux remains unaffected. The Q10 value of the active Na transport derived from the changes of tau varies within the temperature range studied. The Q10 amounts to approximately 1.2 between 42 degrees C and 35 degrees C, to approximately 2.4 between 35 degrees C and 22 degrees C and to approximately 2.1 between 35 degrees C and 17 degrees C. Correspondingly the activation energy of the active Na transport is not constant between 42 degrees C and 17 degrees C. It is calculated to be 3.4 kcal/mol between 42 degrees C and 35 degrees C, 15.9 kcal/mol between 35 degrees C and 22 degrees C and 12.4 kcal/mol between 35 degrees C and 17 degrees C. Variations in temperature change the maximal rate constant of the active Na transport, whereas the sensitivity of the Na pump towards the extracellular K concentration (Ko) is little affected.(ABSTRACT TRUNCATED AT 250 WORDS)
在电压钳制的绵羊浦肯野纤维中，通过同时测量膜电流（I）和细胞内钠活性（αiNa），研究了心脏主动钠转运的温度依赖性。在钠泵激活期间，瞬时外向电流（ΔI）和αiNa以相同的时间常数（τ）呈指数下降。瞬时外向电流和αiNa的下降被10⁻⁴M双氢哇巴因（DHO）阻断。将温度从42℃降至17℃会延长τ。主动钠外流的电生分数（e.f.）保持不变。在所研究的温度范围内，由τ变化得出的主动钠转运的Q10值有所不同。在42℃至35℃之间，Q10约为1.2；在35℃至22℃之间，约为2.4；在35℃至17℃之间，约为2.1。相应地，在42℃至17℃之间，主动钠转运的活化能并非恒定。计算得出，在42℃至35℃之间为3.4千卡/摩尔，在35℃至
