Droogmans G, Casteels R
Pflugers Arch. 1981 Sep;391(3):183-9. doi: 10.1007/BF00596168.
The effect of cooling from 35 to 20 degrees C on the 45Ca-exchange and on the contractile response of rabbit ear artery has been investigated. The amplitude of the contraction induced by K-depolarization at 20 degrees C is reduced to about 60% of its value at 35 degrees C, whereas the response to noradrenaline is not significantly affected. Cooling induces a 2 to 4-fold reduction of the 45Ca-efflux rate. This effect also occurs in Ca-free medium and in solutions containing 1 mM La. It also occurs in Na-free medium and in tissues in which the transmembrane Na-gradient has been reduced. At 20 degrees C, the 45Ca-influx in unstimulated tissues and in K-depolarized preparations is significantly lower than at 35 degrees C. In Ca-depleted tissues, i.e. tissues in which the noradrenaline-sensitive Ca-store has been emptied by a stimulation with the agonist in Ca-free solution, the 45Ca-influx is not significantly affected by cooling. The gradual depletion of the noradrenaline-sensitive Ca-store in Ca-free solutions is at 20 degrees C much slower than at 35 degrees C. The amount of Ca released by noradrenaline is not affected by cooling, whereas for the same amount of Ca released the contractile response is higher at 20 degrees C. These findings indicate that temperature affects the transmembrane Ca-extrusion and the Ca-influx through voltage-dependent channels. The properties of the noradrenaline-sensitive Ca-store are less sensitive to temperature.
研究了将兔耳动脉从35℃冷却至20℃对45Ca交换及收缩反应的影响。20℃时由钾去极化诱导的收缩幅度降至35℃时的约60%，而对去甲肾上腺素的反应未受到显著影响。冷却导致45Ca流出率降低2至4倍。这种效应在无钙培养基和含1 mM镧的溶液中也会出现。在无钠培养基以及跨膜钠梯度降低的组织中同样会出现。在20℃时，未受刺激的组织和钾去极化制剂中的45Ca流入量显著低于35℃时。在钙耗竭的组织中，即通过在无钙溶液中用激动剂刺激使去甲肾上腺素敏感钙储存排空的组织，45Ca流入量不受冷却的显著影响。在无钙溶液中去甲肾上腺素敏感钙储存的逐渐耗竭在20℃时比在35℃时慢得多。去甲肾上腺素释放的钙量不受冷却影响，而对于相同释放量的钙，20℃时的收缩反应更高。这些发现表明温度影响跨膜钙外流以及通过电压依赖性通道的钙内流。去甲肾上腺素敏感钙储存的特性对温度不太敏感。
