Anesthesiology
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The transient receptor potential ankyrin 1 (TRPA1) ion channel is expressed on nociceptive primary afferent nerve fibers. On the distal ending, it is involved in transduction of noxious stimuli, and on the proximal ending (within the spinal dorsal horn), it regulates transmission of nociceptive signals. Here we studied whether the cutaneous or spinal TRPA1 ion channel contributes to mechanical hypersensitivity or guarding, an index of spontaneous pain, in an experimental model of postoperative pain in the rat. ⋯ The TRPA1 channel in the skin contributes to sustained as well noxious mechanical stimulus-evoked postoperative pain, whereas the spinal TRPA1 channel contributes predominantly to innocuous mechanical stimulus-evoked postoperative pain.
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Treating postoperative pain remains a significant challenge for perioperative medicine. Recent studies have shown that nerve growth factor is up-regulated and contributes to incisional pain. To date, few studies have examined expression of other neurotrophin-related mediators that may contribute to the development and/or maintenance of incisional pain. ⋯ Surgical incision is associated with pain-related gene expression changes in skin, muscle, and, to a lesser extent, dorsal root ganglion. The gene expression profile provides clues as to mediators that are involved in peripheral sensitization and pain transmission after surgical incision and also suggest mechanisms for resolution of postoperative pain when more persistent pain syndromes like neuropathic pain continue.
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The daily fluctuations of many physiologic and behavioral parameters are differentially influenced by either central or peripheral clocks in mammals. Since substance P (SP) oscillates in some brain tissues and plays an indispensable role in modulating inflammatory pain at the spinal level, we speculated that SP mediates circadian nociception transmission at the spinal level. ⋯ We conclude that spinal SP probably plays a pivotal role in modulating circadian inflammatory pain and suggest that peripheral circadian-regulated signaling is potentially an essential pathway for circadian nociceptive transmission.
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The incidence of acute kidney injury following severe sepsis is higher in the elderly. We hypothesized that microvascular endothelium is "primed" by aging and that sepsis represents a "second hit," resulting in more severe microvascular complications. ⋯ Ang-2 is increased in older mice, which might cause priming of the endothelial cells. Endothelium responded by a more extensive increase in expression of P- and E-selectin in older mice and increased polymorphonuclear cell influx.