Lindström E G, Andersson R G
Department of Pharmacology, Faculty of Health Sciences, University of Linköping, Sweden.
Am J Respir Crit Care Med. 1995 Apr;151(4):1175-9. doi: 10.1164/ajrccm/151.4.1175.
Excitatory nonadrenergic, noncholinergic (e-NANC) bronchoconstrictor responses have been shown to be mediated by the release of tachykinins from sensory nerves. We investigated whether bronchial-tube contractions evoked by electrical-field stimulation (EFS) or capsaicin coincided with the release of neurokinin A (NKA). We also studied the modulatory action of morphine and the ability of naloxone to affect these responses. We used a guinea pig bronchial-tube preparation denuded of epithelium. The method allows simultaneous measurement of smooth-muscle tension and mediator release. A significant release of NKA-LI, at 37.3% above the basal level, was detected in response to EFS. Morphine pretreatment was found to inhibit the release, and such inhibition was not prevented by naloxone. Contractile responses to EFS coincided with the NKA-LI release. Capsaicin stimulation evoked a significant release (35.4%) of NKA-LI, and this release was accompanied by contractions. Treatment with morphine decreased capsaicin-induced responses, and naloxone reversed the inhibitory effect. In conclusion, both capsaicin- and EFS-induced e-NANC responses were inhibited by morphine treatment. This indicates presynaptic inhibition of tachykinin release from sensory nerves. Furthermore, the ability of naloxone to reverse this inhibitory effect differed in capsaicin- and EFS-challenged preparations.
兴奋性非肾上腺素能、非胆碱能（e-NANC）支气管收缩反应已被证明是由感觉神经释放速激肽介导的。我们研究了电场刺激（EFS）或辣椒素诱发的支气管收缩是否与神经激肽A（NKA）的释放同时发生。我们还研究了吗啡的调节作用以及纳洛酮影响这些反应的能力。我们使用了去除上皮的豚鼠支气管制备物。该方法允许同时测量平滑肌张力和介质释放。对EFS的反应中检测到NKA-LI显著释放，比基础水平高37.3%。发现吗啡预处理可抑制释放，且这种抑制作用不能被纳洛酮阻止。对EFS的收缩反应与NKA-LI释放同时发生。辣椒素刺激引起NKA-LI显著释放（35.4%），且这种释放伴随着收缩。吗啡处理可降低辣椒素诱导的反应，纳洛酮可逆转这种抑制作用。总之，吗啡处理可抑制辣椒素和EFS诱导的e-NANC反应。这表明感觉神经速激肽释放存在突触前抑制。此外，纳洛酮逆转这种抑制作用的能力在辣椒素和EFS激发的制备物中有所不同。
