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Naunyn-Schmiedeberg's Archives of Pharmacology

, Volume 283, Issue 3, pp 223–244 | Cite as

Analysis of the compartments involved in the extraneuronal storage and metabolism of isoprenaline in the perfused heart

  • H. Bönisch
  • W. Uhlig
  • U. Trendelenburg
Article

Summary

  1. 1.

    Rat hearts were perfused with various concentrations of 3H-(±)-isoprenaline, and initial rates were determined for the removal of the amine from the perfusion fluid and for its O-methylation. Both removal and O-methylation obeyed Michaelis-Menten kinetics, K m and Vmax being 21 μM and 38 nmoles · g−1 · min−1 for the former, and 2.9 μM and 1.7 nmoles · g−1 · min−1 for the latter. After block of COMT the kinetic constants for removal (which equals accumulation under these conditions) were about the same as before. The kinetics of O-methylation seem to differ strikingly from those of accumulation of unchanged amine.

     
  2. 2.

    Corticosterone and 3-O-methylisoprenaline were about equipotent in antagonizing the accumulation and O-methylation of isoprenaline in the rat heart during perfusion with 3H-isoprenaline.

     
  3. 3.

    U-0521 (dihydroxy-2-methyl propiophenone; 100 μM) was used as a blocker of COMT. In addition it was found to be a weak inhibitor of the extraneuronal uptake of isoprenaline (K i =230 μM).

     
  4. 4.

    After block of COMT and subsequent to perfusion of the heart with 0.95 μM 3H-isoprenaline, efflux curves were determined during wash out with amine-free solution. Four compartments were detected (in order of increasing half time of efflux): I represented the fluid in dead space, cardiac cavities and large vessels; II equalled the extracellular space; III and IV represented extraneuronal storage sites. Corticosterone impaired the filling of compartments III and IV when present during filling. Both corticosterone and 3-O-methylisoprenaline (OMI) delayed the efflux from compartment III when present in the wash out solution only.

     
  5. 5.

    Experiments with guinea-pig hearts showed qualitative similarities between these and rat hearts. However, the storage and the O-methylating capacity of the guinea-pig heart was considerably smaller than that of the rat heart.

     
  6. 6.

    Rat ventricle slices (exposed to 0.95 μM 3H-(±)-isoprenaline for 30 min) were compared with perfused hearts. While the accumulation of 3H-isoprenaline was about 1/4, the total formation of 3H-OMI was only 1/50 of that determined for the perfused heart. This low rate of formation of 3H-OMI was also observed for slices of aorta, vas deferens and spleen, while slices of salivary glands had a high O-methylating capacity. Apparently, perfusion of the heart provides optimal access to the O-methylating compartment which may be located in vascular smooth muscle.

     

Key words

Isoprenaline Extraneuronal COMT Uptake2 Corticosterone Extraneuronal Compartments 

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References

  1. Almgren, O., Jonason, J.: Relative importance of neuronal and extraneuronal mechanisms for the uptake and retention of noradrenaline in different tissues of the rat. Naunyn-Schmiedebergs Arch. Pharmak. 270, 289–309 (1971)Google Scholar
  2. Bönisch, H., Trendelenburg, U.: Extraneuronal removal, accumulation and O-methylation of isoprenaline in the perfused heart. Naunyn-Schmiedeberg's Arch. Pharmacol. 283, 191–218 (1974)Google Scholar
  3. Bönisch, H., Uhlig, W.: Uptake and metabolism of isoprenaline in the isolated perfused heart of the rat and guinea pig. Naunyn-Schmiedeberg's Arch. Pharmacol. 277, R 6 (1973)Google Scholar
  4. Callingham, B. A., Burgen, A. S. V.: The uptake of isoprenaline and noradrenaline by the perfused rat heart. Molec. Pharmacol. 2, 37–42 (1966)Google Scholar
  5. Dick, D. A. T., Lea, E. J. A.: Na fluxes in single toad oocytes with special reference to the effect of external and internal Na concentration on Na efflux. J. Physiol. (Lond.) 174, 55–90 (1964)Google Scholar
  6. Dixon, M.: The determination of enzyme inhibitor constants. Biochem. J. 55, 170–171 (1953)Google Scholar
  7. Dixon, M., Webb, E. C.: Enzymes, 2nd ed. London: Longmans Ltd 1964Google Scholar
  8. Eisenfeld, A. J., Axelrod, J., Krakoff, L.: Inhibition of the extraneuronal accumulation and metabolism of norepinephrine by adrenergic blocking agents. J. Pharmacol. exp. Ther. 156, 107–113 (1967a)Google Scholar
  9. Eisenfeld, A. J., Landsberg, L., Axelrod, J.: Effect of drugs on the accumulation and metabolism of extraneuronal norepinephrine in the rat heart. J. Pharmacol. exp. Ther. 158, 378–385 (1967b)Google Scholar
  10. Graefe, K. H., Trendelenburg, U.: Hydrocortisone-induced supersensitivity to noradrenaline in the isolated nictitating membrane as a consequence of an impairment of an O-methylating system with high affinity. Naunyn-Schmiedeberg's Arch. Pharmacol. 282, R 26 (1974)Google Scholar
  11. Hellmann, G., Hertting, G., Peskar, B.: Uptake kinetics and metabolism of 7-3H-dopamine in the isolated perfused rat heart. Brit. J. Pharmacol. 41, 256–269 (1971)Google Scholar
  12. Iversen, L. L.: The uptake of catechol amines at high perfusion concentrations in the rat isolated heart: A novel catechol amine uptake process. Brit. J. Pharmacol. 25, 18–33 (1965)Google Scholar
  13. Iversen, L. L., Salt, P. J.: Inhibition of catecholamine uptake2 by steroids in the isolated rat heart. Brit. J. Pharmacol. 40, 528–530 (1970)Google Scholar
  14. Jacobowitz, D., Brus, R.: A study of extraneuronal uptake of norepinephrine in the perfused heart of the guinea-pig. Europ. J. Pharmacol. 15, 274–284 (1971)Google Scholar
  15. Jarrott, B.: Uptake and metabolism of catecholamines in the perfused hearts of different species. Brit. J. Pharmacol. 38, 810–821 (1970)Google Scholar
  16. Kaumann, A. J.: Adrenergic receptors in heart muscle: relations among factors influencing the sensitivity of the cat papillary muscle to catecholamines. J. Pharmacol. exp. Ther. 173, 383–398 (1970)Google Scholar
  17. Kaumann, A. J.: Potentiation of the effects of isoprenaline and noradrenaline by hydrocortisone in cat heart muscle. Naunyn-Schmiedeberg's Arch. Pharmacol. 273, 134–153 (1972)Google Scholar
  18. Langer, S. Z., Stefano, F. J. E., Enero, M. A.: Pre- and postsynaptic origin of the norepinephrine metabolites formed during transmitter release elicited by nerve stimulation. J. Pharmacol. exp. Ther. 183, 90–102 (1972)Google Scholar
  19. Mireylees, S. E., Foster, R. W.: 3-Methoxyisoprenaline: a potent selective uptake2 inhibitor. J. Pharm. Pharmacol. 25, 833–835 (1973)Google Scholar
  20. Osswald, W., Branco, D.: The effects of drugs and denervation on removal and accumulation of noradrenaline in the perfused hind-limb of the dog. Naunyn-Schmiedeberg's Arch. Pharmacol. 277, 175–190 (1973)Google Scholar
  21. Powis, G.: The accumulation and metabolism of (±)-noradrenaline by cells in culture. Brit. J. Pharmacol. 47, 568–575 (1973)Google Scholar
  22. Salt, P. J.: Inhibition of noradrenaline uptake2 in the isolated rat heart by steroids, clonidine and methoxylated phenylethylamines. Europ. J. Pharmacol. 20, 329–340 (1972)Google Scholar
  23. Trendelenburg, U., Höhn, D., Graefe, K. H., Pluchino, S.: The influence of block of catechol-O-methyl transferase on the sensitivity of isolated organs to catecholamines. Naunyn-Schmiedebergs Arch. Pharmak. 271, 59–92 (1971)Google Scholar
  24. Uhlig, W., Bönisch, H., Trendelenburg, U.: The O-methylation of extraneuronally stored isoprenaline in the perfused heart. Naunyn-Schmiedeberg's Arch. Pharmacol. 283, 245–261 (1974)Google Scholar
  25. Wilkinson, G. N.: Statistical estimations in enzyme kinetics. Biochem. J. 80, 324–332 (1961)Google Scholar

Copyright information

© Springer-Verlag 1974

Authors and Affiliations

  • H. Bönisch
    • 1
  • W. Uhlig
    • 1
  • U. Trendelenburg
    • 1
  1. 1.Institut für Pharmakologie und Toxikologie der Universität WürzburgWürzburgGermany

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