Objective To evaluate the effects of dexmedetomidine on lidocaine-induced apoptosis in rat cortical neurons.Methods The cortical neurons obtained from Sprague-Dawley fetal rats were seeded in 24 multiwell plates at a density of 1 × 105 cells/ml,and the cortical neurons of 80 wells were randomly divided into 4 groups (n =20 each):control group (group C),lidocaine group (group L),dexmedetomidine group (group D) and lidocaine + dexmedetomidine group (group L+ D).The cells were cultured routinely in group C.The cells were exposed to lidocaine with a final concentration of 1 mmol/L in group L.The cells were exposed to dexmedetomidine with a final concentration of 3 μmol/L in group D.The cells were exposed to lidocaine and dexmedetomidine with the final concentrations of 1 mmol/L and 3 μmol/L,respectively,in group L + D.After 4 h incubation,the neurons were subjected to DAPI staining for detection of apoptosis,and the apoptosis rate was calculated.Western blot analysis was used to measure the expression of phosphorylated Akt (p-Akt),Akt and caspase-3.Results Compared with group C,the apoptosis rate was significantly increased,the expression of p-Akt was down-regulated,and the expression of caspase-3 was up-regulated in L and L + D groups (P ＜ 0.05),while no significant changes were found in the indexes mentioned above in group D (P ＞ 0.05).Compared with group L,the apoptosis rate was significantly decreased,the expression of p-Akt was up-regulated,and the expression of caspase-3 was down-regulated in L + D group (P ＜ 0.05).There was no significant difference in the expression of Akt between the four groups (P ＞ 0.05).Conclusion Dexmedetomidine can reduce lidocaine-induced apoptosis in rat cortical neurons,and activation of Akt may be involved in the underlying mechanism.

Objective To investigate the role of Akt signaling in the protective effect of dexmedetomidine preconditioning on the lipopolysaccharide(LPS)-induced acute lung injury (ALI) in rat .Methods Twenty-two SD rats were randomly divided into 4 groups:before LPS injection group(T0 group) ,1 h after LPS injection group(T1 group) ,3 h after LPS injection group(T2 group) and 6 h after LPS injection group(T3 group) ,the expression of Akt and p-Akt in the process of LPS-induced ALI was investigated . Another 54 rats were divided into 3 groups :control group(C group) ,6 hours of ALI group(ALI group) and Dexmedetomidine+ALI group(D+ ALI group) ,the expression of p-Akt in lung tissues ,the protein concentration in bronchoalveolar lavage fluid (BALF) ,apoptotic index and the pathological changes in the lung tissues were observed .Forty rats were divided into ALI group and ALI + D group to investigate the 48 h-survival ratio .Results Compared with T0 group ,the level of p-Akt expression in T1 ,T2 , T3 groups were deceased in a time-dependent manner(P<0 .05) .Compared with ALI group ,p-Akt in D + ALI group increased significantly(P<0 .05) but was still lower than that in C group(P<0 .05);the protein concentration in BALF and the apoptotic in-dex in D + ALI groups were significantly lower than those in ALI group(P<0 .05) ,but still higher than those in C group(P<0 .05) .The 48 h survival ratio was significantly decreased in D + ALI group comparing with ALI group(P<0 .05) .Conclusion Dexmedetomidine preconditioning might display protective effect via activating p-Akt signaling pathway in LPS-induced ALI .

Objective To evaluate the efficacy of different doses of dexmedetomidine mixed with ropivacaine for brachial plexus block.Methods One hundred and twenty ASA physical status Ⅰ or Ⅱ patients of both sexes,aged 20-60 yr,weighing 40-70 kg,scheduled for upper extremity surgery under brachial plexus block,were randomly divided into 6 groups (n =20 each):ropivacaine group (group R) and different doses of dexmedetomidine groups (groups RD1-5).Brachial plexus block was performed using the interscalene approach.In group R,interscalene brachial plexus block was performed using 0.5 ％ ropivacaine 25 ml (single injection).In groups RD1.5,interscalene brachial plexus block was induced with a mixture (25 ml) of dexmedetomidine 0.25,0.50,0.75,1.00,1.25μg/kg and 0.5 ％ ropivacaine,respectively.The onset time and duration of sensory and motor block were recorded.The adverse effects such as adverse cardiovascular events,excessive sedation,and pneumothorax were also recorded.Results Compared with group R,the onset time was significantly shortened,and the duration of block was prolonged (P ＜ 0.05).Compared with groups RD1 and RD2,the onset time was significantly shortened,and the duration of block was prolonged in groups RD3 5 (P ＜ 0.05).There was no significant difference in the parameters mentioned above between groups RD1 and RD2 or among groups RD3,RD4 and RD5 (P ＞ 0.05).Some patients developed bradycardia,hypotension or excessive sedation in groups RD4 and RD5,while no adverse effects were observed in the other groups.Conclusion Dexmedetomidine 0.75 μg/kg mixed with 0.5 ％ ropivacaine 25 ml can be safely and effectively used for brachial plexus block in patients.