Effects of d-tubocurarine on rat cardiac muscarinic receptors: a comparison with gallamine

J Recept Res. 1988;8(6):787-808. doi: 10.3109/10799898809049026.


Gallamine and d-tubocurarine inhibited (3H)N-methyl-scopolamine [3H)NMS) binding to rat cardiac muscarinic receptors with I50 values of 0.7 microM and 22 microM, respectively. They decreased the association and dissociation rates of the two ligands (3H)NMS and (3H)Oxotremorine M [3H)Oxo-M). Gallamine interaction with muscarinic receptors was markedly inhibited by (3H)NMS and (3H)Oxo-M binding to the receptors. We were unable to demonstrate (3H)NMS or (3H)Oxo-M binding to the muscarinic receptor-gallamine complex. By contrast, d-tubocurarine interaction with rat cardiac muscarinic receptors was facilitated by (3H)Oxo-M binding and only slightly inhibited by (3H)NMS binding to muscarinic binding sites. Furthermore, (3H)NMS and (3H)Oxo-M bound to the receptor-d-tubocurarine complex, indicating that the latter drug interacted with an allosteric site on cardiac muscarinic receptors but did not recognize the muscarinic binding site (at concentrations below 1 mM).

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding, Competitive
  • Gallamine Triethiodide / pharmacology*
  • Heart / drug effects*
  • In Vitro Techniques
  • Kinetics
  • Male
  • N-Methylscopolamine
  • Rats
  • Rats, Inbred Strains
  • Receptors, Muscarinic / drug effects*
  • Receptors, Muscarinic / metabolism
  • Scopolamine Derivatives / metabolism
  • Tubocurarine / pharmacology*


  • Receptors, Muscarinic
  • Scopolamine Derivatives
  • Gallamine Triethiodide
  • N-Methylscopolamine
  • Tubocurarine