Objective To evaluate the pharmacokineties of ropivacaine for single sciatic nerve block in dogs.Methods Twelve healthy adult mongrel dogs weighing 14-17 kg were randomized to receive 0.5% ropivaeaine 10 mg/kg or 20 mg/kg for single sciatic nerve block(n=6 each).ECG,BP and HR were monitored and recorded during anesthesia.Blood samples were obtained from femoral artery before ropivacaine injection (baseline)and at 10,20,30,40,60,90,120,150,180,240,360 and 720 min after ropivacaine injeetion for determination of plasma ropivaeaine concentration(by reversc-phasc high performance liquid chromatography).Arterial blood samples were also taken when adverse reactions occurred.The pharmacokinetic parameters were eMeulated with DAS 1.0 software package.Results The concentration-time curve of ropivacaine for single sciatic nenre block was fitted to two-compartment open model in both groups.The peak plasma concentration of ropivaeaine was significantly lower in 10 mg/kg group than in 20 mg/kg group.Two dogs developed convulsion in 20 mg/kg group.The plasma ropivaeaine concentration was 12.56 and 13.67 mg/L respectively during convulsion.Conclusion Pharmaeokinetic profile of ropivaeaine for single sciatic nerve block is best described by two-compartment model.Bopivaeaine 20 mg/kg for sciatic nerve block can hardly be tolerated by dogs.

After first report of local anesthetics on cardiac toxicity was published in 1979, A lot of researches of local anesthetics on the mechanism of cardiac toxicity and its treatments were reported, and some advances were reviewed in this article during recent years.

NMDA(N-Methyl-D-Aspartate)receptor is a kind of ionotropic receptors, which have been widely localized in peripheral somatic tissues and visceral pain pathways. The activation or expression changes of peripheral NMDA receptor may play an important role in pain occurrence. Peripheral administration of NMDA receptor antagonist can alleviate or prevent pain and enhance the analgesic effect of opiate. This method of administration can reduce the side effect of central action induced by the drug. It will be an important research direction of pain management.

As a new laboratory test for evaluation of endogenous pain inhibition,conditioned pain modulation (CPM) deficiency means dysfunction of endogenous pain inhibitory systems and higher incidence of chronic pain.Age,psychological factors and physical activity all seem to influence the individual CPM effect.A standard CPM testing way has an important role in comparison between different researches.

Spinal opioids have been widely used in clinical anesthesia and analgesia. In this article, we reviews the characteristics about the clinical applications of spinal opioids, including the opioid selection, drug dosage, administration route, effects of different opioids, drug combination, associated adverse effects and so on.

Objective To investigate the effect of ketamine pretreatment on acute tolerance to morphine in rats with chronic inflammatory pain.Methods Twenty-four adult male SD rats weighing 180-200 g were randomly divided into 3 groups (n=8 each): group Ⅰ morphine (M) ,group Ⅱ ketamine (K) and group Ⅲ ketamine + morphine (KM). Chronic inflammatory pain was induced by subcutaneous injection of Freund's adjuvant 0.125 ml into the plantar surface of left hindpaw. Three days after Freund's adjuvant injection, the animals received intraperitoneal (IP) morphine 5 mg/kg in group M, IP ketamine 10 mg/kg in group K or IP ketamine 10 mg/kg 10 min before IP morphine 5 mg/kg in group KM once a day for 3 consecutive days respectively. The paw withdrawal threshold to yon Frey hair stimulation (PWT) and paw withdrawal latency to noxious thermal stimulation(PWLT) using the hot plate test were measured before Freund's adjuvant injection (T0, baseline), and every day before (T1) and at 15 (T2), 30 (T3), 60 (T4) and 120 min (T5) after medication for 3 days (D1,2,3).Results PWT was significantly increased after medication on D1,2,3 in group KM but only on D1,2 in group M. PWLT was significantly prolonged after medication on D1,2,3 in group KM but only on D1 in group M. Conclusion Ketamine 10 mg/kg pretreatment can decrease the acute tolerance to morphine in rats with chronic inflammatory pain.

Objective To evaluate the effect of gabapentin on Cav3.2 channels in the dorsal root ganglia ( DRG) of rats with neuropathic pain. Methods Thirty male Sprague?Dawley rats, aged 6-7 weeks, weighing 225-275 g, were divided into 3 groups ( n=10 each) using a random number table:sham operation group ( S group) , neuropathic pain group ( NP group) and gabapentin group ( G group) . In NP and G groups, neuropathic pain was induced by chronic constriction injury to the left sciatic nerve. Starting from 7th day after operation, gabapentin 100 mg∕kg in 1 ml of normal saline was injected intraper?itoneally twice a day for 7 consecutive days in group G, and the equal volume of normal saline was given twice a day for 7 consecutive days in S and NP groups. The mechanical paw withdrawal threshold ( MWT) and thermal paw withdrawal latency ( TWL) were measured on day 3 before operation and on postoperative days 3, 7 and 14. After the last measurement of pain thresholds on the postoperative day 14, 4 rats were sacrificed for determination of Cav3. 2 mRNA expression ( by real?time polymerase chain reaction) and Cav3.2 protein expression (by Western blot) in the DRG. Results Compared with S group, the MWT was significantly decreased, and TWL was significantly shortened on postoperative days 3, 7 and 14, and the expression of Cav3.2 protein and mRNA in the DRG was significantly up?regulated in group NP, and the MWT was significantly decreased, and TWL was significantly shortened on postoperative days 3 and 7 ( P<0.05), and no significant change was found in the expression of Cav3.2 protein and mRNA in the DRG in group G ( P>0.05) . Compared with NP group, the MWT was significantly increased, and TWL was signif?icantly prolonged on the postoperative day 14, and the expression of Cav3.2 protein and mRNA in the DRG was significantly down?regulated in group G ( P<0.05) . Conclusion The mechanism by which gabapentin attenuates neuropathic pain may be related to inhibition of the function of Cav3.2 channels in the DRG of rats.

Mild hypothermia significantly increases perioperative complications,such as adverse myocardial outcomes,coagulopathy,infection and delayed recovery.So it is important to maintain the core temperature above 36 ℃.Redistribution is the major cause of hypothermia during the first hour of intravertebral or general anesthesia.There are many methods to protect patients from hypothermia including passive insulation and active warming.Forced-air and electric heating pad are currently the most effective noninvasive choices.The contribution of intravenous fluids heating to patients' temperature is limited but it should be performed when large volume is required.

Although there are a number of shortcomings with these animal models, they provide important clues in understanding the underlying pathophysiology of neuropathic pain in humans. In these models, cutaneous sensory threshold of the hindlimb ipsilateral to nerve injury is measured. The presence of neuropathic pain in experimental animal models is mainly measured as allodynia or hyperalgesia, in which the normally nonnoxious or mildly noxious stimuli induce a nociceptive behavioral response. This paper mainly discusses the recent findings from the peripheral nerve injury model of neuropathic pain, as well as the different characteristics of these animal models of neuropathic pain.

AIM: To investigate if pregabalin could depress the acute tolerance induced by morphine when curing the chronic inflammatory pain of rats.METHODS: 24 adult male Sprague-Dawley rats weighing 180-200 g were randomly divided into three groups(8 in each group).Freund's adjuvant was injected subcutaneously in left hind-paw of the rat to establish the chronic inflammatory pain model.3 days later,rats received 3 daily intragastrical(p.o.) morphine 8 mg/kg(M group),pregabalin 3 mg/kg(P group) or morphine 8 mg/kg+pregabalin 3 mg/kg(MP group) administrations respectively.The rats' pressure-withdrawal threshold(PWT) and paw withdrawal thermal latency(PWTL) were determined with Von-Frey hair test and rat hot-plate test respectively.The results of PWT and PWTL before and 15,30,60,120 min after medication were recorded.RESULTS: PWT and PWTL of the rats in M group increased after medication on all the time points of the first day and 15 min of the second day(P