Effect of l-ephedrine on cholinergic neurotransmission in the isolated guinea pig ileum.
In the isolated guinea pig ileum, the effects of I-ephedrine on the twitch response to field stimulation were investigated in the presence of propranolol. Ephedrine and clonidine inhibited the twitch response but not the contraction to exogenous acetylcholine. The inhibitory effect of clonidine was significantly diminished by yohimbine pretreatment. However, the inhibitory effect of ephedrine was not influenced by yohimbine, sulpiride or 6-hydroxydopamine (6-OHDA) pretreatment. Most of this action of ephedrine appeared to be cholinergic prejunctional in nature, but unrelated to activation of prejunctional alpha 2-adrenoceptors and dopamine sensitive receptors on the cholinergic nerves in this preparation.
Yamamoto
R
R
Department of Pharmacology, Miyazaki Medical College, Japan.
Nuki
C
C
Komidori
H
H
Takasaki
K
K
D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D004809:Ephedrine / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D006892:Hydroxydopamines / Q000494:pharmacology; D007082:Ileum / Q000187:drug effects / Q000294:innervation; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation*; D016627:Oxidopamine; D010275:Parasympathetic Nervous System / Q000187:drug effects*; D013469:Sulpiride / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects*; D014439:Tyramine / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
D006892:Hydroxydopamines; D015016:Yohimbine; D013469:Sulpiride; D016627:Oxidopamine; D004809:Ephedrine; D003000:Clonidine; D014439:Tyramine