Naunyn-Schmiedeberg's Archives of Pharmacology

, Volume 332, Issue 1, pp 16–20

The cardio-selectivity of himbacine: a muscarine receptor antagonist

  • S. Anwar-ul
  • H. Gilani
  • L. B. Cobbin
Article

DOI: 10.1007/BF00633191

Cite this article as:
Anwar-ul, S., Gilani, H. & Cobbin, L.B. Naunyn-Schmiedeberg's Arch. Pharmacol. (1986) 332: 16. doi:10.1007/BF00633191
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Summary

The antimuscarinic actions of himbacine were compared with those of atropine and/or homatropine on atria, ileum and trachea from guinea-pigs and rat uterus preparations.
  1. 1.

    The antagonism of acetylcholine or carbachol by all the antagonists was competitive on the preparations studied. The pA2 values of himbacine in all smooth muscle preparations were similar )around 7.2) whereas in atria it exhibited about 10-fold higher affinity (pA2=8.2).

     
  2. 2.

    In contrast, both atropine and homatropine had similar affinities for muscarine receptors (pA2 values around 9.1 and 7.2 respectively) in both atria and smooth muscle.

     
  3. 3.

    It may be concluded from these results that cardiac and smooth muscle muscarine receptors are not homogeneous and that himbacine is a relatively potent and selective antagonist for cardiac receptors.

     
  4. 4.

    The cardio-selectivity of himbacine supports the concept of heterogeneity of muscarine receptors.

     

Key words

Himbacine Cardio-selective antagonist Cardiac and smooth muscle Muscarine receptor heterogeneity 

Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • S. Anwar-ul
    • 1
  • H. Gilani
    • 1
  • L. B. Cobbin
    • 1
  1. 1.Department of PharmacologyUniversity of SydneyAustralia

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