Shibata K, Takei S, Kawai T, Imaizumi Y, Watanabe M
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Nagoya City University, Japan.
Jpn J Pharmacol. 1989 May;50(1):19-29. doi: 10.1254/jjp.50.19.
The effect of superior cervical ganglionectomy or long term treatment with guanethidine on the mechanical response of dilator muscle of the rat iris to several stimulants was examined. The dose-response curve for noradrenaline (NA) was significantly shifted to the left 7 days after denervation (ca. x 10) or by treatment with guanethidine (ca. x 10), but those for methoxamine (Meth) and acetylcholine (ACh) were not. Cocaine did not further sensitize the denervated muscle to NA, but it sensitized the normal muscle to an extent similar to that caused by denervation. Cocaine did not affect the sensitivity to Meth in both control and denervated muscles. The maximum response to NA decreased by about 30% or 20% after surgical or chemical denervation, respectively, while those to Meth, ACh and Ca2+ did not alter significantly. These results indicate that in the dilator muscle, the sympathetic denervation caused a purely specific supersensitivity to NA which was simply explained by a presynaptic mechanism: an impairment of the neuronal uptake process.
研究了颈上神经节切除术或用胍乙啶长期治疗对大鼠虹膜开大肌对几种刺激的机械反应的影响。去神经支配7天后（约10倍）或用胍乙啶治疗后（约10倍），去甲肾上腺素（NA）的剂量-反应曲线显著左移，但甲氧明（Meth）和乙酰胆碱（ACh）的曲线未发生左移。可卡因并未使去神经支配的肌肉对NA进一步敏感，但它使正常肌肉敏感的程度与去神经支配所引起的程度相似。可卡因对对照肌肉和去神经支配肌肉对Meth的敏感性均无影响。手术或化学去神经支配后，对NA的最大反应分别降低约30%或20%，而对Meth、ACh和Ca2+的最大反应无明显改变。这些结果表明，在开大肌中，交感神经去神经支配导致对NA产生纯粹特异性的超敏感性，这可以通过突触前机制简单解释：神经元摄取过程受损。
