Summary
Strips of canine saphenous vein were loaded with 3H-noradrenaline (1.4 μM) and perifused with Krebs solution and either subjected to field stimulation or exposed to tyramine 40 μM. 3H, noradrenaline and its metabolites were determined in the perifusion fluid. Stimulation caused an increase predominantly in noradrenaline, followed by DOPEG, whereas tyramine released DOPEG in larger amounts than noradrenaline. Tyramine had more sustained effects than stimulation. Cocaine (1.6 μM) drastically reduced DOPEG efflux due to stimulation, but had no effects on the pattern of release by tyramine. It is concluded that tyramine releases noradrenaline which is deaminated before it reaches the synaptic gap, whereas after stimulation deamination of the transmitter occurs after re-uptake.
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References
Brandão, F.: Inactivation of norepinephrine in an isolated vein. J. Pharmacol. Exp. Ther. 202, 23–29 (1977)
Dubocovich, M., Langer, S. Z.: Influence of the frequency of nerve stimulation on the metabolism of 3H-norepinephrine released from the perfused cat spleen: differences observed during and after the period of stimulation. J. Pharmacol. Exp. Ther. 198, 83–101 (1976)
Guimarães, S., Osswald, W.: Adrenergic receptors in the vein of the dog. Eur. J. Pharmacol. 5, 133–140 (1969)
Langer, S. Z., Enero, M. A.: The potentiation of responses to adrenergic nerve stimulation in the presence of cocaine: Its relationship to the metabolic fate of released norepinephrine. J. Pharmacol. Exp. Ther. 191, 431–443 (1974)
Leitz, F. H., Stefano, F. J. E.: The effect of tyramine, amphetamine and metaraminol on the metabolic disposition of 3H-norepinephrine released from the adrenergic neuron. J. Pharmacol. Exp. Ther. 178, 464–473 (1971)
Lindmar, R., Muscholl, E.: Die Verstärkung der Noradrenalin-Wirkung durch Tyramin. Naunyn-Schmiedebergs Arch. Exp. Path. Pharmak. 251, 122–133 (1965)
Luchelli-Fortis, M. A., Langer, S. Z.: Reserpine-induced depletion of the norepinephrine stores: is it a reliable criterion for the classification of the mechanism of action of sympathomimetic amines? J. Pharmacol. Exp. Ther. 188, 640–653 (1974)
Tainter, M. L., Chang, D. K.: The antagonism of the pressor action of tyramine by cocaine. J. Pharmacol. Exp. Ther. 30, 193–207 (1927)
Trendelenburg, U.: Classification of sympathomimetic amines. In: Handb. der experimentellen Pharmakologie (H. Blaschko and E.Muscholl, eds.), Vol. XXXIII, pp. 336–362. Berlin-Heidelberg-New York: Springer 1972
Verbeuren, T. J., Coen, E., Vanhoutte, P. M.: Determination of 3H-norepinephrine and its metabolites in superfusate from isolated blood vessels. Arch. Int. Pharmacodyn. 227, 171–174 (1977)
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Results presented in part to the 8th Annual Meeting of the Portuguese Pharmacological Society (Coimbra, December 1977) and to the 3rd International Symposium on Vascular Neuroeffector Mechanisms (Louvain-Antwerpen, July 24–26, 1978). This work was supported by a grant from Instituto Nacional de Investigação Científica (FmPl)
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Brandão, F., Monteiro, J.G. & Osswald, W. Differences in the metabolic fate of noradrenaline released by electrical stimulation or by tyramine. Naunyn-Schmiedeberg's Arch. Pharmacol. 305, 37–40 (1978). https://doi.org/10.1007/BF00497004
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DOI: https://doi.org/10.1007/BF00497004