Foster K A, Arch J R, Newson P N, Shaw D, Taylor S G
SmithKline Beecham Pharmaceuticals, Epsom, Surrey, UK.
Eur J Pharmacol. 1992 Nov 3;222(1):143-51. doi: 10.1016/0014-2999(92)90826-p.
The effects of cromakalim, verapamil and salbutamol have been examined in guinea pig trachealis smooth muscle in both Krebs physiological salt solution and Krebs solution where K+ has been replaced by Rb+. Cromakalim-induced relaxation in the presence of Rb+ was reduced in extent and became transient, whilst the relaxation response to verapamil was enhanced and that to salbutamol unaffected. The transient relaxation occurring in Rb+ was blocked by quinidine and glibenclamide. The presence of extracellular Rb+ also prevented cromakalim-stimulated efflux of both 86Rb+ and 42/43K+. There was, however, no effect on cromakalim-stimulated 86Rb+ uptake. It is proposed that cromakalim is opening two populations of potassium channel in guinea pig tracheal smooth muscle, one of which is susceptible to blockade by Rb+ and one of which is not. The latter channel appears to play the dominant role in cromakalim-stimulated uptake, and is responsible for the transient relaxation response in the presence of rubidium, whilst the former is responsible for the maintained relaxation.
在豚鼠气管平滑肌中，已分别在 Krebs 生理盐溶液和用 Rb⁺替代 K⁺的 Krebs 溶液中研究了克罗卡林、维拉帕米和沙丁胺醇的作用。在存在 Rb⁺的情况下，克罗卡林诱导的舒张程度降低且变得短暂，而对维拉帕米的舒张反应增强，对沙丁胺醇的舒张反应则未受影响。在 Rb⁺存在时出现的短暂舒张被奎尼丁和格列本脲阻断。细胞外 Rb⁺的存在也阻止了克罗卡林刺激的⁸⁶Rb⁺和⁴²/⁴³K⁺外流。然而，对克罗卡林刺激的⁸⁶Rb⁺摄取没有影响。有人提出，克罗卡林在豚鼠气管平滑肌中打开了两类钾通道，其中一类易受 Rb⁺阻断，另一类则不受影响。后一种通道似乎在克罗卡林刺激的摄取中起主导作用，并导致在存在铷的情况下出现短暂舒张反应，而前一种通道则负责持续的舒张。
