Objective: Using the method of lactate dehydrogenase (LDH) assay, to observe the activities of rat cerebral microvascular endothelial cells (CMECs) intervened by Tongluo Jiunao Injection (TLJNI), a traditional Chinese compound drug removing toxin to dredge brain collaterals, and then further study the effects of different kinds of conditioned mediums (CMECs-CM) of cerebral microvascular endothelial cells on ischemia and ischemia/reperfusion cerebral cortex cells, and to probe into the drug pharmacological mechanisms of CMECs in modulating the neurons. 

Methods: Three kinds of CMECs (normal, ischemic and ischemic/reperfusional) were all treated by TLJNI previously, and then the three pairs of CMECs-CM without serum were collected respectively for LDH assay. Rat cerebral cortex neurons were also primarily cultured and then divided into similar three groups (normal, ischemic and ischemic/reperfusional). The neuron responses caused by CMECs-CM at different concentrations were observed by using LDH transudation rate assay. 

Results: The LDH release values of ischemic and ischemic/reperfusional CMECs with TLJNI treatment were obviously reduced (P＜0.01) compared with the same kinds of CMECs untreated. For ischemic neurons, both conditioned medium of ischemic CMECs (Is-CM) and conditioned medium of ischemic CMECs with drug treatment (IsT-CM) in high concentration of 100% increased the LDH transudation rate (P＜0.01), while in low concentration of 10%, IsT-CM reduced the transudation rate (P＜0.05). For ischemia/reperfusion neurons, all kinds of CMECs-CM reduced the transudation rate respectively (P＜0.05 or P＜0.01). As far as each group concentration was concerned, 10% or 50% showed relatively stronger effects, and both conditioned medium of normal CMECs (N-CM) group and conditioned medium of ischemic/reperfusional CMECs (Rp-CM) group had statistical significance (P＜0.05 or P＜0.01). For normal neurons, all kinds of CMECs-CM increased the transudation rate respectively (P＜0.05 or P＜0.01). As far as each group concentration was concerned, only conditioned medium of normal CMECs (N-CM)had statistical significance (P＜0.05 or P＜0.01). 

Conclusion: The study shows that TLJNI is capable of preventing the damage of CMECs from both ischemia and ischemia/reperfusion states. Chinese drug can restrain the brain ischemia and ischemia/reperfusion damage by the media that CMECs modulate the neurons, demonstrating the pharmacological mechanisms of TLJNI. This work also indicates that there exist some active substances against ischemia/reperfusion injury secreted from CMECs-CM with TLJNI treatment.

Key words: cerebral microvascular endothelial cells, neurons, cerebral ischemia, rats, Chinese herbal drugs