Radomirov R, Venkova K
Department of Experimental Pharmacology, Bulgarian Academy of Sciences, Sofia.
Neuropharmacology. 1988 Jul;27(7):729-35. doi: 10.1016/0028-3908(88)90082-2.
The contractile responses of the longitudinal smooth muscle layer of the isolated guinea-pig ileum which were elicited by long-lasting (40 sec train duration) electrical field stimulation (0.8 msec, 20 V), applied at a frequency of either 5 or 30 Hz, comprised an initial phasic component followed by a secondary tonic contraction, were studied against the background of postsynaptically-acting receptor antagonists. Atropine and apamin reduced both components of the responses while prazosin produced no change. Propranolol induced a slight reduction, decreasing mainly the responses evoked by stimulation at a frequency of 5 Hz. The simultaneous application of cholinoceptor and adrenoceptor blockers revealed a non-cholinergic, non-adrenergic component of the responses. The putative prostaglandin antagonist, SC 19220 was found to reduce mainly the tonic component of the non-cholinergic, non-adrenergic contractions evoked by stimulation at both frequencies used. These results demonstrated that the two-component contractile responses of the guinea pig ileum to long-lasting electrical stimulation were due to the release of more than one neurotransmitter and/or spasmogenic substance. It is concluded that the initial phasic component was evoked by acetylcholine and by a non-cholinergic, non-adrenergic neurotransmitter, while the tonic component was maintained predominantly by prostaglandins released during stimulation.
在突触后作用的受体拮抗剂的背景下，研究了豚鼠离体回肠纵行平滑肌层由持续（40秒 train 持续时间）电场刺激（0.8毫秒，20伏）引发的收缩反应，刺激频率为5或30赫兹。该收缩反应包括一个初始的相性成分，随后是继发性强直性收缩。阿托品和蜂毒明肽降低了反应的两个成分，而哌唑嗪则没有变化。普萘洛尔引起轻微降低，主要降低5赫兹频率刺激所诱发的反应。胆碱能受体和肾上腺素能受体阻滞剂的同时应用揭示了反应中的非胆碱能、非肾上腺素能成分。发现假定的前列腺素拮抗剂SC 19220主要降低两种使用频率刺激所诱发的非胆碱能、非肾上腺素能收缩的强直性成分。这些结果表明，豚鼠回肠对持续电刺激的双成分收缩反应是由于不止一种神经递质和/或致痉物质的释放。得出的结论是，初始相性成分是由乙酰胆碱和一种非胆碱能、非肾上腺素能神经递质诱发的，而强直性成分主要由刺激期间释放的前列腺素维持。
