Department of Cellular Physiology, Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi-dori, Niigata 951-8510, Japan.
Clin Exp Nephrol. 2011 Apr;15(2):203-11. doi: 10.1007/s10157-010-0382-0. Epub 2010 Dec 14.
Gap junction intercellular communication plays a fundamental role in various tissues and organs. Gap junctions transfer ions and molecules between adjacent cells and are formed by connexins (Cx). It is supposed that vascular conducted responses, which most likely spread through gap junctions in vascular beds, regulate microcirculatory blood flow and maintain vascular resistance. This study provides functional evidence supporting the critical role of gap junctions in a physiological setting and in phenylephrine (PE)-induced vasoconstriction using an ex vivo kidney perfusion technique.
Using the isolated, perfused kidney model, infusion of gap junction inhibitors and PE, we examined the local effect of gap junction communication. Additionally, gap junction proteins Cx37, Cx40 and Cx43 were detected by immunofluorescence.
First, changes in the perfusion pressure were analyzed by infusing the nonselective gap junction uncoupler, 18α-glycyrrhetinic acid (18α-GA), and specific connexin-mimetic peptide inhibitors, (37,43)Gap27, (40)Gap27 and (43)Gap26. Administration of 18α-GA and (43)Gap26 significantly elevated perfusion pressure while infusion of (40)Gap27 and (37,43)Gap27 had no effect. Second, we examined the effect of infusing gap junction inhibitors on PE-induced vasoconstriction. Infusion of 18α-GA and (40)Gap27 significantly suppressed the increase in perfusion pressure induced by PE, while (43)Gap26 and (37,43)Gap27 had no effect. Third, we confirmed by immunofluorescence that Cx37, Cx40 and Cx43 were found in the endothelial cells of interstitial microvessels and that Cx40 was localized in glomerular mesangial cells as well as in smooth muscle cells of the juxtaglomerular area.
This study showed that Cx43 plays a pivotal role in regulating renal vascular resistance and that Cx40 attenuates PE-induced vasoconstriction. These results provide new evidence that gap junctions may control renal circulation and vascular responses.
细胞间隙连接通讯在各种组织和器官中发挥着基本作用。缝隙连接通过连接蛋白（Connexins，Cx）在相邻细胞间传递离子和分子。血管介导的反应（vascular conducted responses）很可能通过血管床中的缝隙连接传播，调节微循环血流并维持血管阻力。本研究通过离体肾脏灌注技术，提供了功能证据，支持缝隙连接在生理状态和苯肾上腺素（PE）诱导的血管收缩中的关键作用。
使用分离灌注的肾脏模型，输注缝隙连接抑制剂和 PE，我们检测了缝隙连接通讯的局部作用。此外，通过免疫荧光检测缝隙连接蛋白 Cx37、Cx40 和 Cx43。
首先，通过输注非选择性缝隙连接解偶联剂 18α-甘草次酸（18α-GA）和特定的连接蛋白模拟肽抑制剂（37,43）Gap27、（40）Gap27 和（43）Gap26，分析灌注压的变化。给予 18α-GA 和（43）Gap26 显著升高灌注压，而（40）Gap27 和（37,43）Gap27 没有作用。其次，我们检测了输注缝隙连接抑制剂对 PE 诱导的血管收缩的影响。输注 18α-GA 和（40）Gap27 显著抑制了 PE 引起的灌注压升高，而（43）Gap26 和（37,43）Gap27 没有作用。第三，免疫荧光证实 Cx37、Cx40 和 Cx43 存在于间质微血管的内皮细胞中，Cx40 定位于肾小球系膜细胞以及近球小体的平滑肌细胞中。
本研究表明 Cx43 在调节肾脏血管阻力方面发挥着关键作用，Cx40 减弱了 PE 诱导的血管收缩。这些结果提供了新的证据，表明缝隙连接可能控制肾脏循环和血管反应。
