1] Department of Physiology, Medical College of Shihezi University, Shihezi, PR China [2] The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, PR China.
1] The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, PR China [2] Department of Pathophysiology, Medical College of Shihezi University, Shihezi, PR China.
Hypertens Res. 2014 Feb;37(2):110-5. doi: 10.1038/hr.2013.120. Epub 2013 Sep 19.
To investigate the effects of hypertension on the changes in gap junctions between vascular smooth muscle cells (VSMCs) in the mesenteric artery (MA) of spontaneously hypertensive rats (SHRs). Whole-cell patch clamp, pressure myography, real-time quantitative reverse transcription PCR (qRT-PCR), western blot analysis and transmission electron microscopy were used to examine the differences in expression and function of the gap junction between MA VSMCs of SHR and control normotensive Wistar-Kyoto (WKY) rats. (1) Whole-cell patch clamp measurements showed that the membrane capacitance and conductance of in-situ MA VSMCs of SHR were significantly greater than those of WKY rats (P<0.05), suggesting enhanced gap junction coupling between MA VSMCs of SHR. (2) The administration of phenylephrine (PE) and KCl (an endothelium-independent vasoconstrictor) initiated more pronounced vasoconstriction in SHR versus WKY rats (P<0.05). Furthermore, 2-APB (a gap junction inhibitor) attenuated PE- and KCl-induced vasoconstriction, and the inhibitory effects of 2-APB were significantly greater in SHR (P<0.05). (3) The expression of connexin 45 (Cx45) mRNA and protein in the MA was greater in SHR versus WKY rats (P<0.05). The level of phosphorylated Cx43 was significantly higher in SHR versus WKY rats (P<0.05), although the expression of total Cx43 mRNA and protein in the MA was equivalent between SHR and WKY rats. Electron microscopy revealed that the gap junctions were significantly larger in SHR versus WKY rats. Increases in the expression of Cx45 and phosphorylation of Cx43 may contribute to the enhancement of communication across gap junctions between MA VSMCs of SHR, which may increase the contractile response to agonists.
为了研究高血压对自发性高血压大鼠（SHR）肠系膜动脉（MA）血管平滑肌细胞（VSMC）间隙连接变化的影响。我们使用全细胞膜片钳、压力肌动描记法、实时定量逆转录 PCR（qRT-PCR）、Western blot 分析和透射电子显微镜检查了 SHR 和对照正常血压 Wistar-Kyoto（WKY）大鼠 MA VSMC 间隙连接表达和功能的差异。（1）全细胞膜片钳测量显示，SHR 原位 MA VSMC 的膜电容和电导明显大于 WKY 大鼠（P<0.05），提示 SHR MA VSMC 间隙连接偶联增强。（2）苯肾上腺素（PE）和 KCl（一种非内皮依赖性血管收缩剂）的给药引发了 SHR 比 WKY 大鼠更为明显的血管收缩（P<0.05）。此外，2-APB（间隙连接抑制剂）减弱了 PE 和 KCl 诱导的血管收缩，并且 2-APB 在 SHR 中的抑制作用明显更大（P<0.05）。（3）MA 中连接蛋白 45（Cx45）mRNA 和蛋白的表达在 SHR 中大于 WKY 大鼠（P<0.05）。与 WKY 大鼠相比，SHR 中磷酸化 Cx43 的水平显著升高（P<0.05），尽管 MA 中 Cx43 的总 mRNA 和蛋白表达在 SHR 和 WKY 大鼠之间是等效的。电子显微镜显示，SHR 中的间隙连接明显大于 WKY 大鼠。Cx45 的表达增加和 Cx43 的磷酸化可能有助于增强 SHR MA VSMC 间隙连接的通讯，从而增加对激动剂的收缩反应。
