Anesthesiology
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Comparative Study
Painful nerve injury decreases resting cytosolic calcium concentrations in sensory neurons of rats.
Neuropathic pain is difficult to treat and poorly understood at the cellular level. Although cytoplasmic calcium ([Ca]c) critically regulates neuronal function, the effects of peripheral nerve injury on resting sensory neuronal [Ca]c are unknown. ⋯ Painful SNL nerve injury depresses resting [Ca]c in sensory neurons. This is most marked in axotomized neurons, especially the large and capsaicin-insensitive neurons presumed to transmit non-nociceptive sensory information.
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Comparative Study
Effects of remifentanil on N-methyl-D-aspartate receptor: an electrophysiologic study in rat spinal cord.
Remifentanil hydrochloride contained in Ultiva (GlaxoSmithKline, Genval, Belgium) has been incriminated in difficult postoperative pain management, promotion of hyperalgesia, and direct N-methyl-D-aspartate (NMDA) receptor activation, but the involved mechanisms have remained unclear. In the current study, the authors investigated the effects of remifentanil hydrochloride, with and without its vehicle, glycine, on the activation of NMDA receptors and the modulation of NMDA-induced current on neurons inside the lamina II from the dorsal horn of rat spinal cord. ⋯ These results show that remifentanil hydrochloride does not directly activate NMDA receptors. The NMDA current recorded after application of Ultiva is related to the presence of glycine. Induced NMDA current is potentiated by application of remifentanil hydrochloride through a pathway involving the mu-opioid receptor.
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In patients homozygous for atypical plasma cholinesterase, mivacurium causes a long-lasting neuromuscular block, but injection of human cholinesterase has been proven effective in antagonizing the block. The purpose of this study was to evaluate the pharmacodynamics and pharmacokinetics of mivacurium in such patients, as well as the effect of cholinesterase injected early or late after mivacurium. ⋯ As expected, the duration of action of mivacurium is markedly prolonged in homozygous atypical patients. Injection of cholinesterase significantly increases the metabolism of mivacurium, leading to a shorter duration of action. Injection of neostigmine after the administration of cholinesterase speeds up recovery.
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Comparative Study
Developmental age influences the effect of epidural dexmedetomidine on inflammatory hyperalgesia in rat pups.
Epidural alpha2-adrenergic agonists produce analgesic effects in children and adults, but efficacy and safety have not been established in neonates and infants. The aim of this study was to determine the effect of epidural dexmedetomidine on sensory processing, reversal of inflammatory hyperalgesia, and sedation during early development in rats. ⋯ Spinally mediated selective reversal of inflammatory hyperalgesia by epidural dexmedetomidine can be achieved at all ages; relatively lower doses are effective in early life, but the therapeutic window is narrow. These data have implications for the use and dosing of epidural alpha2 agonists in neonates and infants.