Johnson S M
Department of Physiology, Flinders University of South Australia, Bedford Park.
Eur J Pharmacol. 1990 May 16;180(2-3):331-8. doi: 10.1016/0014-2999(90)90318-z.
This study examined whether the inhibitory actions of opioids in the guinea-pig ileum were influenced by agents which mimic or elevate intracellular cyclic adenosine 3',5'-monophosphate (cyclic AMP) levels. In longitudinal muscle-myenteric plexus preparations, the mu agonist, [D-Ala2,NMePhe4,Gly-ol5]enkephalin (DAGO) and the kappa agonist, dynorphin A-(1-13) depressed contractions of the longitudinal muscle evoked by electrical stimulation of myenteric neurons. Mean IC50 values were 19 and 2.8 nM for DAGO and dynorphin, respectively. Neither forskolin, cholera toxin nor dibutyryl cyclic AMP affected significantly the IC50s for the opioid agonists. The experiments suggest that mu and kappa agonists inhibit excitatory cholinergic transmission to the longitudinal muscle by intracellular effector mechanisms that do not involve cyclic AMP.
本研究考察了模拟或提高细胞内环磷酸腺苷（cAMP）水平的试剂是否会影响阿片类药物对豚鼠回肠的抑制作用。在纵行肌-肠肌丛制备物中，μ激动剂[D-Ala2，NMePhe4，Gly-ol5]脑啡肽（DAGO）和κ激动剂强啡肽A-（1-13）可抑制肠肌神经元电刺激诱发的纵行肌收缩。DAGO和强啡肽的平均半数抑制浓度（IC50）值分别为19 nM和2.8 nM。福斯高林、霍乱毒素和二丁酰环磷腺苷均未显著影响阿片类激动剂的IC50。实验表明，μ和κ激动剂通过不涉及环磷腺苷的细胞内效应机制抑制向纵行肌的兴奋性胆碱能传递。
