Advertisement

Evidence that (+)-bupranolol interacts directly with myocardial β-adrenoceptors

Control of optical purity with differential thermal analysis
  • Wilfried Wächter
  • Ulrich Münch
  • Horst Lemoine
  • Alberto J. Kaumann
Article

Summary

Melting points measured with the capillary method were 150.5°C, 150.5°C and 224.0°C for hydrochlorides of (+)-bupranolol, (−)-bupranolol and (±)-bupranolol, respectively. The large difference in melting points of 73.5°C prompted us to determine possible contaminations of (+)-bupranolol with traces of (−)-bupranolol using differential scanning calorimetry. We detected as little as 0.001% (−)-bupranolol in a standard mixture of (+)-bupranolol and (−)-bupranolol. A batch of (+)-bupranolol not measurably contaminated with (−)-bupranolol (optically purity>99.999%) was used in pharmacological and biochemical assays.

The affinities of (−)-bupranolol and (+)-bupranolol were determined functionally by the blockade of isoprenaline stimulation of spontaneously beating rat right atria and electrically driven kitten papillary muscles; and directly by the inhibition of binding of 3H-(−)-propranolol to kitten ventricle membrane particles. In all 3 systems the enantiomeric (−)/(+) affinity ratio was 50–120 for bupranolol. These experiments prove that (+)-bupranolol itself binds to the β-adrenoceptors of mammalian myocardium.

Key words

99.999% (DTA) pure (+)-bupranolol Heart β-adrenoceptors (−)/(+) enantiomeric affinity ratio Inotropism Chronotropism 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Arunlakshana, O., Schild, H.O.: Some quantitative uses of drug antagonists. Br. J. Pharmacol. 14, 48–58 (1959)Google Scholar
  2. Blinks, J. R.: Convenient apparatus for recording of isolated heart muscle. J. Appl. Physiol. 20, 755–757 (1965)Google Scholar
  3. Buckner, C. K., Patil, P. N.: Steric aspects of adrenergic drugs. XVI. Beta adrenergic receptors of guinea-pig atria and tracheae. J. Pharmacol. Exp. Ther. 176, 634–649 (1971)Google Scholar
  4. Cheng, Y. C., Prusoff, W. H.: Relationship between the inhibition constant (Ki) and the concentration of inhibitor which causes 50 per cent inhibition (I50) of an enzymatic reaction. Biochem. Pharmacol. 22, 3099–3108 (1973)Google Scholar
  5. Easson, L. H., Stedman, E.: CLXX. Studies on the relationship between chemical constitution and physiological action. V. Molecular dissymmetry and physiological activity. Biochem. J. 27, 1257–1266 (1933)Google Scholar
  6. Eliel, E. L.: Stereochemistry of carbon compounds. McGraw-Hill in Advanced Chemistry. New York 1962Google Scholar
  7. Fouquey, C., Jacques, J.: Détermination de la pureté optique d'un corps cristallin par une méthode calorimétrique. Tetrahedron 23, 4009–4019 (1967)Google Scholar
  8. Kaumann, A. J.: Some differences between heart-β-adrenoceptors of reserpine-pretreated rat (Wistar II) and frogs (Xenopus laevis). Naunyn-Schmiedeberg's Arch. Pharmacol. 297, R 49 (1977a)Google Scholar
  9. Kaumann, A. J.: Relaxation of heart muscle by catecholamines and by dibutyryl cyclic adenosine 3′,5′-monophosphate. Similarity of β-adrenoceptors meadiating contractile and relaxant effects of catecholamines in kitten papillary muscle. Naunyn-Schmiedeberg's Arch. Pharmacol. 296, 205–215 (1977b)Google Scholar
  10. Kaumann, A. J.: On spare β-adrenoceptors for inotropic effects of catecholamines in kitten ventricle. Naunyn-Schmiedeberg's Arch. Pharmacol. 305, 97–102 (1978)Google Scholar
  11. Kaumann, A. J., Birnbaumer, L.: Characteristics of the adrenergic receptor coupled to myocardial adenyl cyclase. Stereospecificity for ligands and determination of apparent affinity constants for β-blockers. J. Biol. Chem. 249, 7874–7885 (1974)Google Scholar
  12. Kaumann, A. J., Blinks, J. R.: Stimulant and depressant effects of β-adrenoceptor blocking agents on isolated heart muscle: A non-adrenomimetic positive inotropic effect. Naunyn-Schmiedeberg's Arch. Pharmacol. 311, 205–218 (1980)Google Scholar
  13. Kaumann, A. J., Wittmann, R., Birnbaumer, L., Hoppe, B. H.: Activation of myocardial β-adrenoceptors by the nitrogen-free low affinity ligand 3′,4′-dihydroxy-α-methylpropiophenone (U-0521). Naunyn-Schmiedeberg's Arch. Pharmacol. 296, 217–228 (1977)Google Scholar
  14. Kaumann, A. J., Birnbaumer, L., Wittmann, R.: Heart β-adrenoceptors. In: Receptors and hormone action, Vol. III, pp. 133–177 (O'Malley, B. W., Birnbaumer, L. eds.). New York: Academic Press 1978Google Scholar
  15. Kaumann, A. J., McInerny, T. K., Gilmour, D. P., Blinks, J. R.: Comparative assessment of β-adrenoceptor blocking agents as simple competitive antagonists in isolated heart muscle: Similarity of inotropic and chronotropic blocking potencies against isoproterenol. Naunyn-Schmiedeberg's Arch. Pharmacol. 311, 219–236 (1980)Google Scholar
  16. Kuhnert-Brandstätter, M., Ulmer, R., Langhammer, L.: Thermoanalytische Untersuchungen an Mentholen. Arch. Pharm. 307, 497–503 (1974)Google Scholar
  17. Lemoine, H., Kaumann, A. J.: Agonist-dependent enantiomeric affinity ratios of bupranolol (BU) as a tool for the differentiation of heart- and tracheal β-adrenoceptors using 99.99% optically pure (+)-bupranolol. Naunyn-Schmiedeberg's Arch. Pharmacol. 311, R 60 (1980)Google Scholar
  18. Levitzki, A., Atlas, D., Steer, M.: The binding characteristics and number of β-adrenergic receptors in turkey erythrocyte. Proc. Natl. Acad. Sci. USA 71, 2773–2776 (1974)Google Scholar
  19. Lowry, O. W., Rosebrough, N. J., Farr, A. L., Randall, R. J.: Protein measurements with the folin phenol reagent. J. Biol. Chem. 193, 265–275 (1951)Google Scholar
  20. Mackenzie, R. C.: Differential thermal analysis. Vol. 1. London, New York: Academic Press 1970Google Scholar
  21. Mukherjee, C., Caron, M. C., Coverstone, M., Lefkowitz, R. L.: Identification of adenylate cyclase coupled β-adrenergic receptors in frog erythrocytes with (−)-3H-alprenolol. J. Biol. Chem. 250, 4869–4876 (1975)Google Scholar
  22. Patil, P. N.: A use of the isomeric ratio as a criterion to differentiate adrenergic receptors. J. Pharm. Pharmacol. 21, 628–629 (1969)Google Scholar
  23. Patil, P. N., Miller, D. D., Trendelenburg, U.: Molecular geometry and adrenergic drug activity. Pharmacol. Rev. 26, 323–392 (1975)Google Scholar
  24. Patil, P. N., Patel, D. G., Krell, R. D.: Steric aspects of adrenergic drugs. XV. Use of isomeric activity ratio as a criterion to differentiate adrenergic receptors. J. Pharmacol. Exp. Ther. 176, 622–633 (1971)Google Scholar
  25. Scatchard, G.: The attractions of proteins for small molecules and ions. Ann. Acad. Sci. 51, 660–672 (1949)Google Scholar
  26. Wendlandt, M. W.: Thermal methods of analysis. 2nd ed. New York: John Wiley & Sons 1974Google Scholar

Copyright information

© Springer-Verlag 1980

Authors and Affiliations

  • Wilfried Wächter
    • 1
  • Ulrich Münch
    • 1
  • Horst Lemoine
    • 2
  • Alberto J. Kaumann
    • 2
  1. 1.Pharmazeutische EntwicklungSanol Schwarz GmbHMonheim
  2. 2.Klinische PhysiologiePhysiologisches Institut der UniversitätDüsseldorfFederal Republic of Germany

Personalised recommendations