Refined Qing Kai Ling (RQKL) is an improved injectable multi-component preparation derived from Qing Kai Ling, which could offer the neuroprotection effect in middle cerebral artery occlusion (MCAO) model of rats by relieving the damage of vascular endothelial cell as well as inhibiting the process of inflammation. Herein, we observed whether RQKL could exert influence on the expression of endothelial nitric oxide synthase (eNOS), as a mechanism of its protective effects against ischemia. Sprague-Dawley rat model of focal cerebral ischemia was established by permanent filament occlusion of the left middle cerebral artery. We found that the administration of RQKL could reduce the ischemic infarct size as well as neurological deficit of model rats. Furthermore, it was showed that the eNOS level was consistently increased in endothelium of blood vessels of the ischemic penumbra after 2 to 72 h of permanent MCAO, and the expression of eNOS increases more in animals treated with RQKL. Our results suggested that eNOS levels in penumbral zone were enhanced after permanent focal ischemia, and RQKL could stimulate postischemic eNOS expression, which may be an important mechanism in RQKL's protection against cerebral ischemia.
2008 The Pharmaceutical Society of Japan