过氧化亚硝酸根参与重症休克血管反应性低下的发生

目的　从血管平滑肌膜电位和细胞内钙离子变化 ,探讨一氧化氮 (NO)引起重症休克血管反应性下降的机制。　方法　复制大鼠失血性休克模型 ,测定脊斜肌微动脉对去甲肾上腺素(NE)的反应性。休克至血管反应性下降时分离肠系膜细动脉平滑肌细胞 (ASMC) ,用荧光探针和激光共聚焦显微镜测定NO供体S -亚硝基 -N -乙酰青霉胺 (SNAP)对ASMC膜电位和游离钙离子浓度的影响 ,用超氧阴离子清除剂Tiron、鸟苷酸环化酶抑制剂ODQ、钙激活钾通道 (Kca)抑制剂蝎毒 (ChTX)、ATP敏感钾通道 (KATP)抑制剂优降糖 (GLY)预处理细胞后观察上述影响的变化。　结果　SNAP使ASMC超极化 ,预加Tiron完全阻断该效应 ;分别加ODQ、ChTX、GLY和三者合用预处理细胞 ,可部分阻断SNAP的作用。SNAP还可使ASMC内游离钙浓度下降 ,Tiron能阻断该作用。　结论　大量NO与超氧阴离子 (O　 )形成的过氧化亚硝酸根 (OONO )引起血管平滑肌细胞超极化 ,带来平滑肌细胞内钙离子浓度下降 ,它是休克后期血管反应性下降的重要原因。OONO 可通过KATP、Kca、cGMP等途径引起血管平滑肌超极化

Peroxynitrite involves in the pathogenesis of vascular hyporeactivity during severe shock

Objective To study the cellular mechanism of the effects of nitric oxide (NO) on vascular hyporeactivity in severe hemorrhagic shock (HS). Methods Hemorrhagic shock model in rats was reproduced and vascular reactivity to norepinephrine was determined. The constant MAP of 40 mmHg was maintained until vascular hyporeactivity had occurred and then the rats were sacrificed. Mesenteric arteriolar smooth muscle cells (ASMC) were isolated to study the effects of NO donor SNAP on membrane potential (MP) and intracellular free calcium concentration ([Ca 2 ]i) by fluorescent probes and confocal microscopy in the absence and presence of Tiron, an intracellular scavenger of O , glybenclamide (GLY), a blocker of K ATP channels, charybdotoxin (ChTX ), a blocker of Kca channels, and ODQ, a guanylyl cyclase inhibitor. Results High concentration of SNAP hyperpolarized ASMC dramatically, which was completely blocked in the presence of Tiron , and partially blocked in the presence of GLY, ChTX, and ODQ respectively or together. SNAP could also decrease [Ca 2 ]i of ASMC, which could be completely blocked in the presence of Tiron. Conclusions Peroxynitrite (OONO -), formed by high concentration of NO and O in severe HS causes hyperpolarization of ASMC, and then decreases [Ca 2 ]i, may be partially responsible for the occurrence of vascular hyporeactivity in severe HS. Activation of K ATP and Kca channels and formation of cGMP are the reasons for the hyperpolarization induced by OONO