[Preconditioning of morphine protects rabbit myocardium from ischemia-reperfusion injury].

OBJECTIVE: To investigate the protective effects of preconditioning morphine on rabbit myocardium during ischemia-reperfusion. METHODS: Thirty New Zealand male white rabbits were randomly assigned to three groups: control, I/R and morphine groups. In morphine group 1.0 mg/kg morphine was given preoperationaly, in control and I/R groups 1.0 ml/kg NS was given. Twenty-four hours later rabbits in morphine and I/R groups underwent 40 min of coronary occlusion followed by 2 hours of reperfusion; for control group only sham operation was performed. At the end of the reperfusion, infarct size (IS) and area at risk (AAR) were defined by Evans blue and TTC staining. At the end of the reperfusion blood samples were taken for determination of plasma SOD activity and MDA levels. The heart was harvested and levels of the HSP27 were determined by Western blot, and the heart ultrastructures were observed under the electron microscopy. RESULTS: Compared with I/R group,morphine significantly reduced infarct size (21.5%+/-2.4% Compared with 37.8%+/-1.7%, P<0.05). The morphine had a lower level of MDA and higher levels of SOD and HSP27 than those in I/R. CONCLUSION: Preconditioning of morphine demonstrates cardioprotective effect on ischemia/reperfusion injury, which may be associated with increased HSP27 levels in the heart.

[Protective effect of heat-shock protein 27 on myocardium with isoflurane preconditioning in myocardial ischemia/reperfusion injury of myocardium in rabbit].

OBJECTIVE: To investigate the mechanism and the protective effect of heart-shock protein 27 (HSP27) on rabbit myocardium with isoflurane preconditioning in myocardial ischemia/reperfusion (I/R) injury. METHODS: Thirty New Zealand white rabbits were randomly assigned to three groups (each n = 10):(1)Sham operation group (C group); (2)I/R group; (3)Two percent in volume is of isoflurane group (S group). S group was exposed to 2.0% isoflurane-pure oxygen for 2 hours. C group and I/R group were exposed 2 hours to pure oxygen to serve as untreated controls. Twenty-four hours later the rats in I/R group and S group underwent 40 minutes of coronary occlusion followed by 120 minutes of reperfusion. At the end of the reperfusion, infarct size (IS) was defined by Evan's blue and triphenyltetrazolium chloride (TTC) staining. Blood samples were taken from arterial line for determination of malondialdehyde (MDA) levels. Western Blotting was used to determine the expression of HSP27 and nuclear factor-KappaB (NF-KappaB) in myocardium. RESULTS: Isoflurane preconditioning could decrease I/R induced myocardial infarct size [(19.7 +/- 2.8)% vs.(37.8 +/- 1.7)%]. This was accompanied by an increase in the expression in HSP27 [(84.5 +/- 4.3) gray scale value vs. (53.1 +/- 3.8) gray scale value] and a decrease in NF-KappaB [(58.6 +/- 4.2) gray scale value vs. (119.3+/-5.6) gray scale value] and MDA [(5.24 +/- 0.45)kU/L vs. (9.42 +/- 0.83)kU/L]. CONCLUSION: The expression of HSP27 induced by isoflurane preconditioning plays an important role in protecting myocardium against ischemia/reperfusion injury.

Effect of intraoperative high-dose remifentanil on postoperative pain: a prospective, double blind, randomized clinical trial.

BACKGROUND: Remifentanil, an ultra-short-acting opioid, is widely used for pain control during surgery. However, regular dose (RD) remifentanil exacerbates postoperative pain in a dose-dependent manner. Recent studies suggest that high-dose (HD) remifentanil offers sustained analgesia in experimental studies. We thus hypothesized that intraoperative administration of high-dose remifentanil may attenuate postoperative pain. METHODS: In this prospective, randomized, double blind, controlled clinical study, sixty patients undergoing thyroidectomy (18-60 years-of-age) received an intraoperative infusion of 0.2 (RD group) or 1.2 µg kg(-1) min(-1) (HD group) remifentanil during thyroidectomy. A visual analogue scale (VAS) was used to measure pain intensity. Mechanical pain threshold on the forearm was assessed using von Frey filaments before surgery (baseline), 2 h postoperatively and 18-24 h postoperatively. The primary outcome was to compare the difference of VAS score at different time points after operation and morphine consumption 24 h postoperatively between RD and HD groups. The second outcome was to compare the difference of mechanical pain thresholds in the forearm postoperatively between RD and the HD groups. RESULTS: VAS scores were lower 30 min postoperatively in the HD group (1.29 ± 1.67, 95% CI 0.64-1.94) compared with the RD group (2.21 ± 1.67, 95% CI 1.57-2.84) (t = 3.427, p = 0.0043, RD group vs. HD group). Postoperative morphine consumption was much lower in the HD group compared with the RD group (1.27 ± 1.88 mg vs. 0.35 ± 1.25 mg, p = 0.033). In both groups, mechanical pain threshold was decreased 18-24 h postoperatively (2.93 ± 0.209 Ln(g) vs. 3.454 ± 2.072 Ln(g), p = 0.032 in RD group; 2.910 ± 0.196 Ln(g) vs. 3.621 ± 0.198 Ln(g), p = 0.006 in HD group, 18-24 h postoperatively vs baseline). CONCLUSIONS: Intraoperative administration of high-dose remifentanil decreased VAS scores and morphine consumption postoperatively. Thus, modulation of intraoperative opiates may be a simple and effective method of postoperative pain management. TRIAL REGISTRATION: This trial is registered in ClinicalTrials.gov, with the Name: Effect of Higher Doses of Remifentanil on Postoperative Pain in Patients Undergoing Thyroidectomy, and ID number: NCT01761149.