阻断肠淋巴液回流提高休克大鼠血管钙敏感性的作用与蛋白激酶C有关

Involvement of protein kinase C in enhancement of vascular calcium sensitivity by blocking mesenteric lymph return in hemorrhagic shock rats

本研究旨在观察蛋白激酶C(protein kinase C,PKC)是否参与了肠淋巴管结扎或肠淋巴液引流对失血性休克大鼠血管钙敏感性的调节作用。Wistar雄性大鼠分为假手术组(Sham)、失血性休克组(Shock)、休克+肠淋巴管结扎组(Shock+Ligation,休克手术前行肠淋巴管结扎)、休克+肠淋巴液引流组(Shock+Drainage,休克手术前行肠淋巴液引流),在休克3h时间点,分离出肠系膜上动脉(superior mesenteric artery,SMA)组织,检测PKC蛋白水平与磷酸化PKC(p-PKC)活性;制备SMA血管环,检测各组SMA血管环对梯度[Ca2+]的敏感性,其指标包括收缩性、最大收缩力(Emax)和50%最大反应时的[Ca2+]负对数(pD2),另取Shock+Ligation与Shock+Drainage组SMA血管环分别与PKC调节剂PMA和Staurosporine孵育后,观察钙敏感性变化。结果显示,Shock组SMA的PKC水平、p-PKC活性、对梯度[Ca2+]的收缩性均显著低于Sham组,而Shock+Ligation组与Shock+Drainage组的以上指标均显著高于Shock组。PKC激动剂PMA提高了Shock+Ligation和Shock+Drainage组大鼠SMA血管环对梯度[Ca2+]的收缩性与Emax值;而PKC抑制剂Staurosporine则显著降低了Shock+Ligation和Shock+Drainage组大鼠SMA血管环对梯度[Ca2+]的收缩性和Emax值。以上结果提示,PKC参与了阻断肠淋巴液回流对休克大鼠血管钙敏感性的增强作用。

The aim of the present study was to investigate whether protein kinase C （PKC） was involved in the effect of mesenteric lymph duct ligation or mesenteric lymph drainage on vascular calcium sensitivity in hemorrhagic shock rats.Male Wistar rats were randomly divided into Sham,Shock （hemorrhagic shock）,Shock＋Ligation （mesenteric lymph duct ligation plus shock） and Shock＋Drainage （mesenteric lymph drainage plus shock） groups.After being in shock （hypotension 40 mmHg） for 3 h,the tissue of superior mesenteric artery （SMA） was taken out for detecting the PKC expression and phospho-PKC （p-PKC） activity,and the vascu-lar rings of SMA were prepared and used to measure the response to gradient calcium concentration for assaying the calcium sensitiv-ity,the parameters of which including tension,maximum tension （Emax） and negative logarithm of EC50,called the pD2.Other vascular rings from Shock＋Ligation and Shock＋Drainage groups were incubated with PKC regulator PMA or Staurosporine before the mea-surement of calcium sensitivity.The results showed that,PKC expression,p-PKC activity and calcium sensitivity of SMA in Shock group was significantly lower than that of Sham group,whereas the above-mentioned indexes were significantly elevated in Shock＋Ligation and Shock＋Drainage groups compared with those in Shock group.PKC agonist PMA enhanced the contractile activity of vascular rings to gradient calcium ions,and increased Emax of SMA in Shock＋Ligation and Shock＋Drainage groups.On the con-trary,PKC inhibitor Staurosporine significantly decreased the response to gradient calcium ions and Emax of SMA in Shock＋Ligation and Shock＋Drainage groups.These results suggest that PKC plays a role in the improvement of vascular calcium sensitivity by block-ade of mesenteric lymph return in hemorrhagic shock rats.