Pharmacological properties of pteleprenine, a quinoline alkaloid extracted from Orixa japonica, on guinea-pig ileum and canine left atrium.
We have investigated the pharmacological properties of pteleprenine, a quinoline alkaloid, on contractile responses of the guinea-pig ileum and on inotropic responses of the canine left atrium. Although pteleprenine (0.1-1 microM) had no effect on the contraction of the ileum induced by acetylcholine at 10 microM it significantly inhibited acetylcholine-induced contraction of the ileum. Pteleprenine (0.1-10 microM) reduced nicotine induced-contraction of the ileum in a concentration-dependent manner yet had no maximum relaxant effect even at a concentration of 10 microM. From Schild analysis the pA2 of pteleprenine on the guinea-pig ileum was found to be 6.6. The contraction of the ileum induced by 10 microM 1,1-dimethyl-4-phenylpiperazinium, a specific agonist of nicotinic acetylcholine receptors, was concentration-dependently suppressed by 10 nM-10 microM pteleprenine. In contrast, 0.1-10 microM pteleprenine did not antagonize the acetylcholine- and nicotine-induced negative inotropic contractile responses of the canine left atrium. These results show that pteleprenine has inhibitory action against nicotinic acetylcholine receptors in the guinea-pig ileum but not in the canine left atrium. Our findings also suggest that pteleprenine might be a novel lead compound as a nicotinic receptor antagonist.
Department of Pharmacology, Hirosaki University School of Medicine, Japan.
K
K
Seya
I
I
Miki
K
K
Murata
H
H
Junke
S
S
Motomura
T
T
Araki
Y
Y
Itoyama
Y
Y
Oshima
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D004149:Dioxoles / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D006325:Heart Atria / Q000187:drug effects* / Q000378:metabolism; D007082:Ileum / Q000187:drug effects* / Q000378:metabolism; D007564:Japan; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D009538:Nicotine / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology*; D010946:Plants, Medicinal; D015363:Quinolones / Q000494:pharmacology*
D004149:Dioxoles; D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D015363:Quinolones; C111713:pteleprenine; D004246:Dimethylphenylpiperazinium Iodide; D009538:Nicotine; D000109:Acetylcholine