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Background: Levosimendan exerted favorable effects on the initial outcome in the treatment of ventricular fibrillation cardiac arrest. This study investigated the efficacy of levosimendan in the treatment of asphyxiainduced cardiac arrest in rats. Methods: Animals underwent asphyxial cardiac arrest/cardiopulmonary resuscitation, randomized to three treatment groups: epinephrine (10 µg/kg) supplemented with levosimendan (bolus 12 µg/kg and infusion for 1 h, EL group); epinephrine only (10 µg/kg, E group), or levosimendan only (bolus 12 µg/kg and infusion for 1 h, L group). The resuscitation success rate, wet-to-dry ratio of lung, and rate of alveolar and blood gas analysis were recorded. Results: 10 rats in the EL group, 8 in the E group, and 2 in the L group showed an initial return of spontaneous circulation (P < 0.001); among them, 10, 4, and 2 rats survived at the end of a 60-min observation period from each group, respectively (P = 0.001). The coronary perfusion pressure in the EL group was higher than that of either the E or L group (P < 0.05). The lung wet-to-dry weight ratio and rate of damaged alveoli were lower in the EL group than the E group (P < 0.05). Conclusions: In the early stage of resuscitation for asphyxia-induced cardiac arrest in rats, levosimendan supplemented with epinephrine can significantly increase coronary perfusion pressure, reduce lung injury, and ultimately enhance the survival rate. [ABSTRACT FROM AUTHOR]

Background: Activation of NMDA receptors play an important role in the development of remifentanil-induced hyperalgesia. We hypothesized that in addition to ketamine, intrathecal MgSO4 could also relieve thermal and mechanical hyperalgesia in rats. Methods: Initially, 24 Sprague--Dawley rats were divided into control group, remifentanil group, surgical incision group and remifentanil combined with surgical incision group to create an experimental model. Subsequently, 40 rats were divided into control group, model group, model group plus 100 µg MgSO4, 300 µg MgSO4 and 10 µg ketamine respectively. Paw withdrawal mechanical thresholds and paw withdrawal thermal latency tests were performed at -24 h, 2 h, 6 h, 24 h, 48 h, 72 h and 7 day after the surgical procedure. After behavior assessment on the 7th day, remifentanil was given again to ascertain whether or not NMDA antagonists could suppress the re-exposure of remifentanil-induced hyperalgesia. Results: Remifentanil administration plus surgical incision induced significant postoperative hyperalgesia, as indicated by decreased paw withdrawal mechanical thresholds and paw withdrawal thermal latency to mechanical and thermal stimulation. In addition to ketamine, intrathecal MgSO4 (100, 300 µg) dose-dependently reduced remifentanil-induced mechanical and thermal hyperalgesia. Ketamine had less mechanical hyperalgesia in 6 h (p = 0.018), 24 h (p = 0.014) and 48 h (p = 0.011) than 300 µg MgSO4. There was no difference in inhibiting thermal hyperalgesia between the group ketamine and group MgSO4 (300 µg). The rats were given remifentanil again 7 days later after the first exposure of remifentanil. The hyperalgesic effect induced by re-exposure of remifentanil was not reversed in any groups of MgSO4 or ketamine. Conclusions: In addition to ketamine, intrathecal administration of MgSO4 dose-dependently reduced remifentanil-induced hyperalgesia in a surgical incision mode. Re-exposure to remifentanil 1 week later again produced hyperalgesia, and this was not altered by the prior intrathecal treatments in any 4 groups treated with MgSO4 or ketamine. [ABSTRACT FROM AUTHOR]