King B F, Muir T C
Br J Pharmacol. 1981 May;73(1):87-95. doi: 10.1111/j.1476-5381.1981.tb16775.x.
1 The effects of stimulating sympathetic or non-adrenergic non-cholinergic (NANC) nerves or of the addition of noradrenaline (NA) or isoprenaline (Iso) were investigated on carbachol-induced tone and on contractions produced by acetylcholine (ACh) and by pelvic nerve stimulation, in the rabbit rectococcygeus muscle.2 Each procedure reduced carbachol-induced tone; sympathetic and NANC nerve stimulation were equipotent but both were less effective than sympathomimetic drugs, of which Iso was the better. Both Iso and NA, but not sympathetic nerve stimulation, inhibited the contractions produced by pelvic nerve stimulation in a concentration-dependent manner. Against ACh-induced contractions, only Iso was effective. The effects of NANC nerve stimulation on the motor responses to pelvic nerve stimulation or to ACh were not investigated.3 The inhibitory effects of sympathetic nerve stimulation, of Iso and of NA were reduced by propranolol (3 x 10(-6) M) but unaffected by phentolamine (3 x 10(-5) M).4 In the presence of high (45 mM) concentrations of KCl, Iso and NA produced a concentration-dependent inhibition of tone that was antagonized by propranolol (3 x 10(-6) M).5 Methoxamine (4 x 10(-7) to 4 x 10(-5) M) and phenylephrine (5 x 10(-7) to 5 x 10(-5) M) which interact mainly with alpha(1)-adrenoceptors, produced only small, transient reductions in carbachol-induced tone which were subject to tachyphylaxis, unlike those produced by Iso and NA. These inhibitory effects were antagonized by phentolamine (3 x 10(-6) M) or azapetine (3 x 10(-6) M).6 Phenylephrine (5 x 10(-4) M) and high doses (3 x 10(-5) M or greater) of NA enhanced the contractile response to pelvic nerve stimulation and, on occasion, produced muscle contraction. These effects were antagonized by phentolamine (3 x 10(-6) M).7 These results suggest that inhibition of the rectococcygeus, a muscle which has no intramural nerve plexus, can be inhibited by stimulation of extrinsic NANC nerves, the transmitter for which is unknown and by sympathetic nerve stimulation via alpha- and beta-adrenoceptors located postsynaptically on the muscle. Excitatory alpha-adrenoceptors may also be present.
研究了刺激交感神经或非肾上腺素能非胆碱能（NANC）神经，以及添加去甲肾上腺素（NA）或异丙肾上腺素（Iso）对兔直肠尾骨肌中卡巴胆碱诱导的张力以及乙酰胆碱（ACh）和盆腔神经刺激所产生收缩的影响。
每种处理均降低了卡巴胆碱诱导的张力；交感神经和NANC神经刺激的效果相当，但两者均不如拟交感神经药物有效，其中Iso效果更佳。Iso和NA均以浓度依赖性方式抑制盆腔神经刺激所产生的收缩，但交感神经刺激无此作用。对于ACh诱导的收缩，只有Iso有效。未研究NANC神经刺激对盆腔神经刺激或ACh运动反应的影响。
普萘洛尔（3×10⁻⁶ M）可降低交感神经刺激、Iso和NA的抑制作用，但酚妥拉明（3×10⁻⁵ M）对其无影响。
在高浓度（45 mM）氯化钾存在下，Iso和NA产生浓度依赖性的张力抑制，此作用可被普萘洛尔（3×10⁻⁶ M）拮抗。
主要与α₁ -肾上腺素能受体相互作用的甲氧明（4×10⁻⁷至4×10⁻⁵ M）和去氧肾上腺素（5×10⁻⁷至5×10⁻⁵ M），仅使卡巴胆碱诱导的张力产生小的、短暂的降低，且出现快速耐受性，这与Iso和NA所产生的作用不同。这些抑制作用可被酚妥拉明（3×10⁻⁶ M）或阿扎培汀（3×10⁻⁶ M）拮抗。
去氧肾上腺素（5×10⁻⁴ M）和高剂量（3×10⁻⁵ M或更高）的NA增强了对盆腔神经刺激的收缩反应，有时还会引起肌肉收缩。这些作用可被酚妥拉明（3×10⁻⁶ M）拮抗。
这些结果表明，对于没有壁内神经丛的直肠尾骨肌，其抑制作用可通过刺激外在的NANC神经（其递质未知）以及通过位于肌肉突触后膜上的α和β肾上腺素能受体的交感神经刺激来实现。兴奋性α肾上腺素能受体可能也存在。
