关于藤壶肌纤维中钠外流对锂离子行为的一些观察。

Some observations on the behaviour of the sodium efflux in barnacle muscle fibres towards lithium ions.

作者信息

Bittar E E, Chambers G, Brown D

出版信息

Comp Biochem Physiol B. 1983;76(4):921-5. doi: 10.1016/0305-0491(83)90413-3.

PMID:6319078

Abstract

The behaviour of the Na efflux towards Li+ was studied using single barnacle muscle fibres as a preparation. It is found that the Na efflux into Li+-ASW (artificial seawater) is reduced and that this effect is not fully reversed by returning back to Na+-ASW. Preinjection of 100 mM-EGTA reduces the magnitude of the fall of the Na efflux into Li+-ASW. The remaining Na efflux into Li+-ASW is further reduced by external application of 10(-4) M-ouabain. The remaining Na efflux in ouabain-poisoned fibres is reduced by replacing Nae by Li+. However, some fibres show a rise rather than a fall. Fibres loaded with NaCl (by injection) show a prompt and sustained stimulation of the Na efflux when Nae is replaced by Li+. A similar but less pronounced response is often seen with ouabain-poisoned fibres. Injection of LiCl (e.g. a 2 M-solution), causes a 20% fall in Na efflux. Subsequent replacement of Nae by Li+ fails to bring about a fall in the remaining efflux. It is concluded that the Na efflux in these fibres consists of a Na-Na exchange diffusion component which is not mediated by the Na-K pump and that its operation is interrupted by injecting Li+. The relative size of this component is about one-fifth and not one-half of the Na efflux.

摘要

以单个藤壶肌纤维为实验材料，研究了钠离子外流对锂离子的反应。研究发现，钠离子向锂离子人工海水（Li⁺-ASW）中的外流减少，并且当回到钠离子人工海水（Na⁺-ASW）时，这种效应并未完全逆转。预先注射100 mM的乙二醇双四乙酸（EGTA）可降低钠离子向Li⁺-ASW中外流下降的幅度。通过外部施加10⁻⁴ M的哇巴因，可进一步降低剩余的钠离子向Li⁺-ASW中的外流。用锂离子替代钠离子后，哇巴因中毒纤维中剩余的钠离子外流减少。然而，一些纤维显示出上升而非下降。注射氯化钠（通过注射）加载的纤维，当用锂离子替代钠离子时，钠离子外流会迅速且持续地受到刺激。哇巴因中毒的纤维也常出现类似但不太明显的反应。注射氯化锂（例如2 M溶液）会使钠离子外流下降20%。随后用锂离子替代钠离子并不能使剩余外流下降。得出的结论是，这些纤维中的钠离子外流由一个不通过钠钾泵介导的钠-钠交换扩散成分组成，并且其运作会因注射锂离子而中断。该成分的相对大小约为钠离子外流的五分之一而非二分之一。