This study investigated the analgesic potency and site of action of systemic dexmedetomidine, a selective alpha2-adrenoceptor (alpha2 AR) agonist, in normal and neuropathic rats. Ligation of the L5-6 ...spinal nerves produced a chronic mechanical and thermal neuropathic hyperalgesia in rats. von Frey fibers and a thermoelectric Peltier device were used to measure mechanical and heat withdrawal thresholds over the hindpaw. Systemic dexmedetomidine dose-dependently increased the mechanical and thermal thresholds in the control animals (50% effective dose ED50 144 and 180 micro signg/kg intraperitoneally IP, respectively). Neuropathic animals responded to much smaller doses of dexmedetomidine with mechanical and thermal ED50 values of 52 and 29 micro signg/kg IP, respectively. There was no difference between the control and neuropathic animals with respect to dexmedetomidine-evoked sedation, as determined by decreased grid crossings in an open-field activity chamber (ED50 12 and 9 micro signg/kg IP, respectively). Atipamezole, a selective alpha2 AR antagonist, blocked the analgesic and sedative actions of dexmedetomidine in both the neuropathic and control animals. However, L-659,066, a peripherally restricted alpha2 AR antagonist, could only block the analgesic actions of dexmedetomidine in the neuropathic rats, with no effect in control animals. In conclusion, nerve injury enhanced the analgesic but not the sedative potency of systemic dexmedetomidine and may have shifted the site of alpha2 analgesic action to outside the blood-brain barrier. ImplicationsWe tested the analgesic efficacy of the alpha2 agonist dexmedetomidine in normal and nerve-injured rats. The analgesic potency of dexmedetomidine was enhanced after nerve injury with a site of action outside the central nervous system. Peripherally restricted alpha2 agonists may be useful in the management of neuropathic pain.(Anesth Analg 1998;87:941-8)
The effect of broiler litter application rate on bermudagrass Cynodon dactylon (L.) Pers. yield and nutrient uptake, and on phosphorus (P) level of two associated soils was studied over three years. ...Five litter rates (0, 4.48, 8.96, 17.92, and 35.84 Mg h-1; on as-is basis) were applied each year to two geographically associated soils: a Ruston fine sandy loam with no history of litter application and a Savannah fine sandy loam with high soil P due to thirty years of application. Annual forage yield and nutrient uptake increased quadratically in response to application rate. Apparent P recovery averaged 12% on the Ruston soil and 4% on the Savannah soil. Within three years, P levels of both soils were equivalent, indicating that without consideration of litter application rate, P level of even low-P soils can rapidly reach excessive levels.
Opiate receptors in the periaqueductal gray region and alpha2 adrenoceptors in the spinal cord of the rat mediate the antinociceptive properties of nitrous oxide (N2O). The availability of ...genetically altered mice facilitates the detection of the precise protein species involved in the transduction pathway. In this study, the authors establish the similarity between rats and mice in the antinociceptive action of N2O and investigate which alpha2 adrenoceptor subtypes mediate this response.
After obtaining institutional approval, antinociceptive dose-response and time-course to N2O was measured in wild-type and transgenic mice (D79N), with a nonfunctional alpha2A adrenoceptor using tail-flick latency. The antinociceptive effect of N2O was tested after pretreatment systemically with yohimbine (nonselective alpha2 antagonist), naloxone (opiate antagonist), L659,066 (peripheral alpha2-antagonist) and prazosin (alpha2B- and alpha2C-selective antagonist). The tail-flick latency to dexmedetomidine (D-med), a nonselective alpha2 agonist, was tested in wild-type and transgenic mice.
N2O produced antinociception in both D79N transgenic and wild-type litter mates, although the response was less pronounced in the transgenic mice. Antinociception from N2O decreased over time with continuing exposure, and the decrement was more pronounced in the transgenic mice. The antinociceptive response could be dose dependently antagonized by opiate receptor and selective alpha2B-/alpha2C-receptor antagonists but not by a central nervous system-impermeant alpha2 antagonist (L659,066). Whereas dexmedetomidine exhibited no antinociceptive response in the D79N mice, the robust antinociceptive response in the wild-type litter mates could not be blocked by a selective alpha2B-/alpha2C-receptor antagonist.
These data confirm that the antinociceptive response to an exogenous alpha2-agonist is mediated by an alpha2A adrenoceptor and that there appears to be a role for the alpha2B- or alpha2C-adrenoceptor subtypes, or both, in the analgesic response to N2O.
Describes the development of a scale to provide a valid, reliable measure of multicultural sensitivity of teachers toward their students. Elementary school nurses completed a test survey, and ...secondary school health educators completed the final version. Results indicated the Multicultural Sensitivity Scale was a valid, reliable measure of multicultural sensitivity for the samples surveyed. (SM)
News and Short Contributions Barnett, William K.; Kingery, W. David; Close, Angela E. ...
Journal of field archaeology,
07/1991, Volume:
18, Issue:
2
Journal Article
PDF