Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.
Biochem Biophys Res Commun. 2011 Jul 8;410(3):501-7. doi: 10.1016/j.bbrc.2011.06.011. Epub 2011 Jun 7.
Vascular endothelial and smooth muscle cell phenotypes may change dramatically after isolation and in cell cultures. This study was designed to investigate gap junctions coupling in an integrated intact preparation and to test if K(IR) channels modulate resting membrane conductance in "in situ" endothelial cells (EC), and acetylcholine (ACh)-evoked relaxation of the rat superior mesenteric artery.
Whole cell blind patch recordings of ionic currents from in situ EC, dye-coupling experiments, and functional studies were performed in rat superior mesenteric artery.
EC were dye-coupled through gap junctions. 18β-glycyrretinic acid (25 μM) decreased outward and inward currents, the 80% decay of time and time constant of the capacitative transients, capacitance, and increased input resistance. Barium chloride (30 μM) decreased resting and ACh-evoked inward currents, the sensitivity of ACh-evoked relaxation, and decreased both the sensitivity and the maximal relaxation to S-nitroso-N-acetyl penicillamine in arteries with, but not in arteries without endothelium.
The present results suggest that the EC layer of this large artery is electrically coupled, and that K(IR) channels regulate resting inward conductance, hence suggesting that they are of importance for resting membrane potential in in situ EC. Moreover, EC K(IR) channels are involved in ACh-evoked relaxation.
血管内皮和平滑肌细胞表型在分离和细胞培养后可能会发生显著变化。本研究旨在研究整合完整制剂中的缝隙连接偶联，并测试 K(IR)通道是否调节“原位”内皮细胞（EC）的静息膜电导，以及乙酰胆碱（ACh）诱发大鼠肠系膜上动脉的松弛。
在大鼠肠系膜上动脉中进行原位 EC 的全细胞膜片钳盲法记录离子电流、染料偶联实验和功能研究。
EC 通过缝隙连接进行染料偶联。18β-甘草次酸（25 μM）减少外向和内向电流、电容暂态的 80%衰减时间和时间常数、电容，并增加输入电阻。氯化钡（30 μM）减少静息和 ACh 诱发的内向电流、ACh 诱发松弛的敏感性，并降低 S-亚硝基-N-乙酰青霉胺对有内皮和无内皮的动脉的敏感性和最大松弛度。
本研究结果表明，这条大动脉的 EC 层是电偶联的，K(IR)通道调节静息内向电导，因此表明它们对原位 EC 的静息膜电位很重要。此外，EC K(IR)通道参与 ACh 诱发的松弛。
