Drew G M
Eur J Pharmacol. 1977 Mar 21;42(2):123-30. doi: 10.1016/0014-2999(77)90351-x.
The interactions between alpha-adrenoceptor agonists and antagonists on the twitch response of the rat isolated vas deferens to low frequency motor nerve stimulatioh have been examined. Oxymetazoline, clonidine, naphazoline and BAY-1470 caused a concentration-dependent inhibition of the twitch response at concentrations lower than those causing smooth muscle stimulation. The twitch-inhibitory effect of these compounds is thought to result from stimulation of presynaptically located alpha-adrenoceptors. In contrast, phenylephrine and methoxamine exerted little inhibitory effect at concentrations less than those which produced postsynaptic stimulation. The inhibitory effect of clonidine was antagonised by phentolamine, piperoxan, yohimbine and tolazoline, but not by thymoxamine. These results characterise the presynaptic alpha-adrenoceptors in the rat vas deferens as being of the same type as those present in the rabbit pulmonary artery and rat heart, but different from those located post-synaptically in sympathetically innervated tissues.
已研究了α-肾上腺素能受体激动剂和拮抗剂对大鼠离体输精管对低频运动神经刺激的抽搐反应的相互作用。在低于引起平滑肌刺激的浓度下，羟甲唑啉、可乐定、萘甲唑啉和BAY-1470引起抽搐反应的浓度依赖性抑制。这些化合物的抽搐抑制作用被认为是由突触前α-肾上腺素能受体的刺激引起的。相比之下，去氧肾上腺素和甲氧明在低于产生突触后刺激的浓度时几乎没有抑制作用。可乐定的抑制作用被酚妥拉明、哌泊昔生、育亨宾和妥拉唑啉拮抗，但不被噻吗洛尔拮抗。这些结果表明，大鼠输精管中的突触前α-肾上腺素能受体与兔肺动脉和大鼠心脏中的受体属于同一类型，但与交感神经支配组织中突触后受体不同。
