Antimuscarinic action of liriodenine, isolated from Fissistigma glaucescens, in canine tracheal smooth muscle

C. H. Lin, C. M. Yang, F. N. Ko, Y. C. Wu, C. M. Teng

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The antimuscarinic properties of liriodenine, isolated from Fissistigma glaucescens, were compared with methoctramine (cardioselective M2 antagonist) and 4-diphenylacetoxy-N-methylpiperidine (4-DAMP, smooth muscle selective M3 antagonist) by radioligand binding tests, functional tests and measurements of second messenger generation in canine cultured tracheal smooth muscle cells. Liriodenine, pirenzepine, methoctramine and 4-DAMP displaced [3H]-N-methyl scopolamine ([3H]-NMS) binding in a concentration-dependent manner with K values of 2.2 ± 0.4 x 10-6, 3.3 ± 0.7 x 10-7, 8.9 ± 2.3 x 10-8 and 2.3 ± 0.6 x 10-9 M, respectively. The curves for competitive inhibition of [3H]-NMS with liriodenine, methoctramine and 4-DAMP were best fitted according to a two site model of binding, but pirenzepine was best fitted according to a model with one site. Liriodenine and 4-DAMP displayed a high affinity for blocking tracheal contraction (pK(B) = 5.9 and 9.1, respectively) and inositol phosphate formation (pK(B) = 6.0 and 8.9, respectively), but a low affinity for antagonism of cyclic AMP inhibition (pK(B) = 4.7 and 7.8, respectively). Methoctramine blocked cyclic AMP inhibition with a high affinity (pK(B) = 7.4), but it antagonized tracheal contraction and inositol phosphate formation with a low affinity (pK(B) = 6.1 and 6.0, respectively). In conclusion, both M2 and M3 muscarinic receptor subtypes coexist in canine tracheal smooth muscle and are coupled to the inhibition of cyclic AMP formation and phosphoinositide breakdown, respectively. The antimuscarinic characteristics of liriodenine are similar to those of 4-DAMP. It may act as a selective M3 receptor antagonist in canine tracheal smooth muscle.

Original languageEnglish
Pages (from-to)1464-1470
Number of pages7
JournalBritish Journal of Pharmacology
Volume113
Issue number4
Publication statusPublished - 1994
Externally publishedYes

Keywords

  • Fissistigma glaucescens
  • liriodenine
  • muscarinic receptor antagonist
  • tracheal smooth muscle cells

ASJC Scopus subject areas

  • Pharmacology

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