Soler H M, Watkins M T, Albadawi H, Kadowaki H, Patton G M
Department of Surgery, Veterans Administration Medical Center, Boston, MA 02130, USA.
J Surg Res. 1997 Jan;67(1):46-53. doi: 10.1006/jsre.1996.4917.
Under in vivo conditions of ischemia and reperfusion, vascular endothelium (EC) experience concurrent changes in oxygen tension, shear stress, and the local concentration of metabolites. These studies explored the combined effects of shear stress and oxygen tension on EC prostacyclin production. EC grown on microcarrier beads were exposed to 120 min of normoxia and basal shear stress by stirring at 20 rpm. After normoxia, EC were exposed to hypoxia (2% 0(2), 20 rpm), ischemia (2%, 0(2), 5 rpm) or sham ischemia (20% 0(2), 5 rpm). Following hypoxia, EC were reoxygenated (20% 0(2), 20 rpm). After ischemia and sham ischemia, EC were reperfused (20% 0(2), 20 rpm). Minimal accumulation of metabolites occurred during normoxia, hypoxia, and reperfusion. All metabolites were allowed to accumulate in the flasks during ischemia and sham ischemia. Prostacyclin levels were measured by ELISA, and prostaglandin H2 synthase levels in cells were analyzed by immunoblotting. An acute decrease in shear stress decreased prostacyclin production. An acute decrease only in oxygen tension did not alter prostacyclin production significantly. The combined acute decrease in both shear stress and oxygen tension significantly stimulated prostacyclin production for 30 min. By 120 min of ischemia and hypoxia, prostacyclin release was significantly less than sham ischemia. Prostacyclin production after 30 min of reoxygenation was significantly less than that of cells subjected to reperfusion. By 120 min of reperfusion and reoxygenation, there was no significant difference in EC prostacyclin synthesis. These findings suggest that temporal and quantitative aspects of EC prostaglandin synthesis are dependent on both oxygen tension and shear stress.
在体内缺血和再灌注条件下，血管内皮细胞（EC）会同时经历氧张力、剪切应力和局部代谢物浓度的变化。这些研究探讨了剪切应力和氧张力对EC前列环素生成的联合作用。在微载体珠上生长的EC通过以20转/分钟搅拌暴露于120分钟的常氧和基础剪切应力。常氧后，EC暴露于低氧（2% O₂，20转/分钟）、缺血（2% O₂，5转/分钟）或假缺血（20% O₂，5转/分钟）。低氧后，EC再充氧（20% O₂，20转/分钟）。缺血和假缺血后，EC再灌注（20% O₂，20转/分钟）。在常氧、低氧和再灌注期间代谢物积累极少。在缺血和假缺血期间，所有代谢物都在烧瓶中积累。通过酶联免疫吸附测定法测量前列环素水平，并通过免疫印迹分析细胞中前列腺素H2合酶水平。剪切应力的急性降低会减少前列环素的生成。仅氧张力的急性降低不会显著改变前列环素的生成。剪切应力和氧张力的联合急性降低在30分钟内显著刺激了前列环素的生成。到缺血和低氧120分钟时，前列环素释放显著低于假缺血。再充氧30分钟后的前列环素生成显著低于经历再灌注的细胞。到再灌注和再充氧120分钟时，EC前列环素合成无显著差异。这些发现表明，EC前列腺素合成的时间和定量方面取决于氧张力和剪切应力。
