Objective To evaluate the changes in the expression of diplopore potassium ion channel TRESK mRNA in dorsal root ganlion (DRG) in rats with neuropathic pain (NP) .Methods Thirty-two male SD rats weighing 220-250 g were randomly divided into 2 groups ( n = 16 each) : group sham operation (group S) and group NP. NP was induced by ligation and severance of left tibial and common fibular nerves according to the technique described by Decosterd. Eight rats in each group were sacrificed 1 day before and 14 day after operation and their L4,5 DRGs in the operated side were isolated for determination of TRESK mRNA expression by RT-PCR. In the remaining 8 rats in each group paw withdrawal threshold to mechanical stimuli ( MWT) and paw withdrawal latency to a thermal nociceptive stimulus (TWL) were measured at 1 day before (baseline) and 1, 3, 5, 7, 14 day after operation. Results MWT was significantly lower in group NP than in group S. The TRESK mRNA expression in L4,5 DRGs in the operated side was significantly decreased after operation as compared with the baseline before operation in group NP and was significantly lower in group NP than in group S. Conclusion The development and maintenance of NP may be closely related with down-regulation of TRESK mRNA.

Objective To investigate the effect of dexmedetomidine on brachial plexus block with ropivacaine and upper extremity ischemia-reperfusion (I/R) injury in patients undergoing upper extremity surgery. Methods Forty ASA Ⅰ or Ⅱ patients of both sexes, aged 18-55 yr, weighing 45-80 kg, scheduled forupper extremity surgery under brachial plexus block, were randomly divided into 2 groups ( n = 20 each): control group ( group C )and dexmedtomidine group (group D). In group C, brachial plexus block was performed using 0.5% ropivacaine 30 ml. In group D, brachial plexus block was performed with a mixture (30 ml) of 0.5% ropivacaine and 8 mg dexmedetomidine. The efficacy of motor and sensory block was evaluated and the onset time and duration of motor and sensory block were recorded. Venous blood samples were obtained from peripheral vein on the operated side before anesthesia induction (T0), and at 1, 5 and 30 min after tourniquet release (T1-3) to detect the plasma concentrations of MDA and ischemia-modified albumi (IMA). Arterial blood samples were also obtained at the same time points for blood gas analysis. The complications such as nausea and vomiting, respiratory depression, bradycardia and dizziness were recorded. Sufentanil 0.2 μg/kg was given as rescue medication. If the operation could not be completed, general anesthesia was used. Results There was no requirement for rescue analgesics and general anesthesia, and no complications occurred in all the patients. The duration of sensory and motor block was significantly longer, the plasma concentrations of MDA and IMA were significantly lower, and PaO2 and BE were significantly higher in group D than in group C ( P ＜ 0.05). The plasma concentrations of MDA and IMA were significantly higher at T2 and T3 in both groups, the pH value was significantly lower at T1 in group C, PaO2 at T1 and BE at T1 and T2 were significantly lower in both groups than those at T0 ( P ＜ 0.05). Conclusion Dexmedetomidine can not only enhance the efficacy of brachial plexus block with ropivacaine, but also reduce the upper extremity I/R injury caused by tourniquet in patients undergoing upper extremity surgery.

Objective To construct rat TRESK gene recombinant adenovirus expression vector.Methods TRESK full-length cDNA was cloned from rat dorsal root ganglion cells and confirmed by RT-PCR and sequencing. pAd/CMV/V5-DEST-TRESK was then constructed under the control of CMV-promotor. DH5α colibacillus was translated and the positive recombinants were subsequently identified by PCR and DNA sequencing. 293T cells were cotransfected and packed to produce adenovirus. Results The titer of virus was tested using Hole-by-dilution titer method. The full length of TRESK from rat dorsal root ganglion cells is 781 bp. It was demonstrated that the DNA sequencing was completely consistent with TRESK sequencing of rat recorded in GeneBank. The PCR amplification of the pAd/CMV/V5-DEST-TRESK gDNA was matched with pAD-GFP blank vector as anticipated. The titer of the concentrated virus was 1.31×109 TU/ml. Conclusion Rat TRESK gene recombinant adenovirus vector is constructed successfully.

Objective To investigate the effect of sevoflurane preconditioning on TREK-1 channel expression in hippocampus after focal cerebral ischemia-reperfusion (I/R)in rats and the mechanism.Methods Thirty-six male SD rats weighing 240-280 g were randomly divided into 3 groups(n=12 each):group Ⅰ sham operation (group S),group Ⅱ I/R and group Ⅲ sevoflurane preconditioning (group Sevo).Focal cerebral ischemia was produced by inserting a 4-0 nylon thread with rounded tip into right internal jugular vein.The nylon thread was the nylon thread Wag about 18-20 Innl.The right middle cerebral artery(MCA)Wag occluded for 2 h and then released for 24 h reperfusion.The Sevo group inhaled 2.4% sevoflurane for 30 min at l h before ischemia.Neurological deftcits were assessed and scored at the end of 24 h reperfusion (the higher was the score,the severer was the deficit).The cerebral infarct size was determined by TTC staining and the TREK-1 mRNA in hippocampus by RT-PCR.Results The cerebral infarct size was significantly smaller and the neurological deficit scores were significantly lower in Sevo group than in I/R group.The TREK-1 mBNA expression was significantly up-regulated in Sevo group as compared with I/R group.Conclusion Sevoflurane preconditioning Can protect the brain against I/R injury by activating TREK-1 in hippocampus.