大鼠主动脉中铷 - 86和钾 - 42通量的比较。

Comparison of rubidium-86 and potassium-42 fluxes in rat aorta.

作者信息

Smith J M, Sanchez A A, Jones A W

出版信息

Blood Vessels. 1986;23(6):297-309. doi: 10.1159/000158657.

Abstract

Potassium transport has frequently been assessed by measurement of 86Rb. However, recent reports indicated that the K ion channels are selective to K over Rb. Therefore, the purpose of this study was to evaluate whether the basal and stimulated fluxes of Rb and K were equivalent in rat aorta in the absence of endothelium. The ouabain-sensitive (active) uptake of 86Rb and 42K was similar. However, the basal 86Rb efflux was only 80% of the 42K efflux. Norepinephrine and KCl depolarization stimulated 86Rb and 42K effluxes via a calcium-dependent process. The stimulated 86Rb efflux ranged from 56 to 74% of the 42K efflux. Diltiazem reduced the KCl-stimulated 86Rb and 42K effluxes. The 86Rb efflux was 82% of the 42K efflux in the presence of KCl plus diltiazem, similar to that under basal conditions. Substitution of Rb for K in the incubation solution was associated with a marked increase in spontaneous contractile activity. There was no change in the norepinephrine concentration required for a 50% stimulation of contraction or 86Rb efflux from Rb-loaded tissues. We conclude from these studies that the basal and calcium-activated potassium channels are selective for K over Rb and therefore 86Rb fluxes quantitatively underestimate that of 42K. However, 86Rb is an appropriate substitute for the measurement of active K transport.

摘要

钾离子转运情况常通过测量⁸⁶Rb来评估。然而，近期报告指出钾离子通道对K⁺的选择性高于Rb⁺。因此，本研究的目的是评估在无内皮的大鼠主动脉中，Rb⁺和K⁺的基础通量及刺激通量是否相等。哇巴因敏感的（主动）⁸⁶Rb摄取和⁴²K摄取相似。然而，基础状态下的⁸⁶Rb外流仅为⁴²K外流的80%。去甲肾上腺素和氯化钾去极化通过钙依赖过程刺激了⁸⁶Rb和⁴²K外流。刺激后的⁸⁶Rb外流为⁴²K外流的56%至74%。地尔硫卓降低了氯化钾刺激的⁸⁶Rb和⁴²K外流。在存在氯化钾加地尔硫卓的情况下，⁸⁶Rb外流为⁴²K外流的82%，与基础状态下相似。在孵育溶液中用Rb⁺替代K⁺与自发收缩活性显著增加相关。对于Rb⁺负载组织，使收缩或⁸⁶Rb外流产生50%刺激所需的去甲肾上腺素浓度没有变化。我们从这些研究得出结论，基础钾通道和钙激活钾通道对K⁺的选择性高于Rb⁺，因此⁸⁶Rb通量在数量上低估了⁴²K通量。然而，⁸⁶Rb是测量主动钾转运的合适替代物。