Anesthesiology
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Anesthetic preconditioning (APC) with sevoflurane reduces myocardial ischemia-reperfusion injury. The authors tested whether two brief exposures to sevoflurane would lead to a better preconditioning state than would a single longer exposure and whether dual exposure to a lower (L) concentration of sevoflurane would achieve an outcome similar to that associated with a single exposure to a higher (H) concentration. ⋯ These results suggest that APC depends not only on the concentration but also on the protocol used for preconditioning. Similarly to ischemic preconditioning, repeated application of the volatile anesthetic seems to be more important than the duration of exposure in initiating the signaling sequence that elicits APC at clinically relevant concentrations. Therefore, repeated cycles of anesthetic exposure followed by volatile anesthetic-free periods may be beneficial for APC in the clinical setting.
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Synergistic antinociceptive effect of amitriptyline and morphine in the rat orofacial formalin test.
Combination therapy is often used to increase the clinical utility of analgesic agents. The coadministration of two compounds may achieve analgesia at doses lower than those required for either compound alone, leading to enhanced pain relief and reduction of adverse effects. Herein, the authors describe the effect of coadministration of morphine and amitriptyline on cutaneous orofacial inflammatory pain in rats. ⋯ The current study suggests that systemic amitriptyline and morphine synergistically inhibit cutaneous orofacial inflammatory pain in rats.
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Whether volatile anesthetics produce a second window of preconditioning is unclear. The authors tested the hypothesis that isoflurane causes delayed preconditioning against infarction and, further, that cyclooxygenase (COX)-2 mediates this beneficial effect. ⋯ The results indicate that the volatile anesthetic isoflurane produces a second window of preconditioning against myocardial ischemia and reperfusion injury. Furthermore, COX-2 is an important mediator of isoflurane-induced delayed preconditioning.
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Morphine pretreatment via activation of delta1-opioid receptors induces cardioprotection. In this study, the authors determined whether morphine preconditioning induces ischemic tolerance in neurons. ⋯ These data suggest that morphine preconditioning is neuroprotective. This neuroprotection may be delta1-opioid receptor dependent and may involve mitochondrial adenosine triphosphate-sensitive potassium channel activation and free radical production. Because morphine is a commonly used analgesic, morphine preconditioning may be explored further for potential clinical use to reduce ischemic brain injury.