Crane G J, Walker S D, Dora K A, Garland C J
Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, UK.
J Vasc Res. 2003 Mar-Apr;40(2):159-68. doi: 10.1159/000070713.
The distribution of functionally active, inwardly rectifying K (K(IR)) channels was investigated in the rat small mesenteric artery using both freshly isolated smooth muscle and endothelial cells and small arterial segments. In Ca(2+)-free solution, endothelial cells displayed a K(IR) current with a maximum amplitude of 190 +/- 16 pA at -150 mV and sensitivity to block with 30 microM Ba(2+) (n = 7). In smooth muscle cells, outward K current was activated at around -47 +/- 3 mV, but there was no evidence of K(IR) current (n = 6). Furthermore, raising extracellular [K(+)] to either 60 or 140 mM, or applying the alpha(1)-adrenoceptor agonist phenylephrine (PE; 30 microM), failed to reveal an inwardly rectifying current in the smooth muscle cells, although PE did stimulate an iberiotoxin-sensitive outward K current (n = 4). Exogenous K(+) (10.8-16.8 mM) both relaxed and repolarized endothelium-denuded segments of the mesenteric artery contracted with PE. These effects were depressed by 100 microM ouabain but unaffected by either 30 microM BaCl(2) or 3 microM glibenclamide. These data suggest that functional, inwardly rectifying Ba(2+)-sensitive channels are restricted to the endothelial cell layer in the rat small mesenteric artery.
利用新鲜分离的平滑肌细胞、内皮细胞和小动脉段，研究了功能性活性内向整流钾（K(IR)）通道在大鼠小肠系膜动脉中的分布。在无钙溶液中，内皮细胞呈现出一种K(IR)电流，在-150 mV时最大幅度为190±16 pA，对30 μM Ba(2+)敏感（n = 7）。在平滑肌细胞中，外向钾电流在约-47±3 mV时被激活，但没有K(IR)电流的证据（n = 6）。此外，将细胞外[K(+)]提高到60或140 mM，或应用α(1)-肾上腺素能受体激动剂去氧肾上腺素（PE；30 μM），均未能在平滑肌细胞中揭示内向整流电流，尽管PE确实刺激了一种对iberiotoxin敏感的外向钾电流（n = 4）。外源性K(+)（10.8 - 16.8 mM）使与PE收缩的肠系膜动脉内皮剥脱段舒张并复极化。这些效应被100 μM哇巴因抑制，但不受30 μM BaCl(2)或3 μM格列本脲影响。这些数据表明，功能性的、对Ba(2+)敏感的内向整流通道局限于大鼠小肠系膜动脉的内皮细胞层。
