Summary
The mechanism of action of indirectly acting sympathomimetic amines was studied in the rat vas deferens, after inhibition of vesicular uptake (by reserpine), of MAO (by pargyline) and of COMT (by U-0521). 1. K m-values for the neuronal uptake of 12 substrates were determined as the IC50 of the unlabelled substrate inhibiting the initial rate of neuronal uptake of 0.2 μmol/l 3H-(−)-noradrenaline. The IC50 ranged from 0.35 μmol/l (for (+)-amphetamine) to 44.3 μmol/l (for 5-HT). The V max (determined for 8 substrates) was substrate-dependent. 2. Tissues were loaded with 0.2 μmol/l 3H-(−)-noradrenaline and then washed out with amine-free solution. All 12 substrates of uptake1, induced an outward transport of 3H-noradrenaline, and equieffective concentrations were positively correlated with K m. Moreover, the EC50 for release greatly exceeded K m. It is proposed that this discrepancy between EC50 and K m is indicative of the fact that at least four factors (each one in strict dependence on K m) contribute to the initiation of outward transport of 3H-noradrenaline: a) the appearance of the carrier on the inside of the axonal membrane (facilitated exchange diffusion), b) the co-transport of Na+, c) the co-transport of Cl− (both lowering the K m for 3H-noradrenaline at the inside carrier), and d) inhibition of the re-uptake of released 3H-noradrenaline (through competition for the outside carrier). 3. At least for amezinium, V max. appears to limit the maximum rate of outward transport. 4. For some substrates (especially for the highly lipophilic ones) bell-shaped concentration-release curves were obtained. Apparently, inward diffusion of the substrates can lead to partial saturation of the inside carrier. Moreover, if release is expressed as a FRL (fractional rate of loss), loading with 37 μmol/l 3H-(−)-noradrenaline decreased the releasing effect of various substrates. In this case the inside carrier appears to be partially saturated by the high axoplasmic concentration of 3H-noradrenaline. 5. Very high concentrations (especially of highly lipophilic substrates) were able to induce an additional intraneuronal release mechanism, presumably by increasing the pH inside storage vesicles.
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Abbreviations
- COMT:
-
catechol-O-methyl transferase
- DOMAA:
-
dihydroxymandelic acid
- DOPEG:
-
dihydroxyphenylglycol
- FRL:
-
fractional rate of loss (rate of efflux/tissue tritium content)
- 5-HT:
-
5-hydroxytryptamine
- MAO:
-
monoamine oxidase
- OM-fraction:
-
sum of all O-methylated metabolites of noradrenaline, deaminated or not
References
Bönisch H (1984) The transport of (+)-amphetamine by the neuronal noradrenaline carrier. Naunyn-Schmiedeberg's Arch Pharmacol 327:267–272
Bönisch H (1986) The role of co-transported sodium in the effect of indirectly acting sympathomimetic amines. Naunyn-Schmiedeberg's Arch Pharmacol 332:135–141
Bönisch H, Langeloh A (1986) Neuronal efflux of noradrenaline induced by tris or lithium as substitutes for extracellular sodium. Naunyn-Schmiedeberg's Arch Pharmacol 333:13–16
Bönisch H, Rodrigues-Pereira E (1983) Uptake of 14C-tyramine and release of extravesicular 3H-noradrenaline in isolated perfused rabbit hearts. Naunyn-Schmiedeberg's Arch Pharmacol 323:233–244
Bönisch H, Trendelenburg U (1987) Veratridine-induced outward transport of 3H-noradrenaline from adrenergic nerves of the rat vas deferens. Naunyn-Schmiedeberg's Arch Pharmacol 336:621–630
Bönisch H, Fuchs G, Graefe K-H (1986) Sodium-dependence of the saturability of carrier-mediated noradrenaline efflux from noradrenergic neurones in the rat vas deferens. Naunyn-Schmiedeberg's Arch Pharmacol 332:131–134
Burn JH, Rand MJ (1958) The action of sympathomimetic amines in animals treated with reserpine. J Physiol (Lond) 144:314–336
Documenta Geigy (1969) Wissenschaftliche Tabellen, 7th edn. Geigy AG, Pharma Basel
Fischer JF, Cho AK (1979) Chemical release of dopamine from striatal homogenates: Evidence for an exchange diffusion model. J Pharmacol Exp Ther 208:203–209
Friedrich U, Bönisch H (1986) The neuronal noradrenaline transport system of PC-12 cells: Kinetic analysis of the interaction between noradrenaline, Na+ and Cl− in transport. Naunyn-Schmiedeberg's Arch Pharmacol 333:246–252
Göthert M, Hentrich F (1986) Further evidence for the involvement of cyclic AMP in Ca2+-dependent, but not Ca2+-independent, noradrenaline release in the rabbit pulmonary artery. Arch Int Pharmacodyn 284:85–100
Graefe K-H, Trendelenburg U (1974) The effect of hydrocortisone on the sensitivity of the isolated nictitating membrane to catecholamines. Relationship to extraneuronal uptake and metabolism. Naunyn-Schmiedeberg's Arch Pharmacol 286:1–48
Greene LA, Rein G (1977) Release, storage and uptake of catecholamines by a clonal cell line of nerve growth factor (NGF) responsive pheochromocytoma cells. Brain Res 129:247–263
Grohmann M, Trendelenburg U (1984) The substrate specificity of uptake2 in the rat heart. Naunyn-Schmiedeberg's Arch Pharmacol 328:164–173
Johnson RG, Scarpa A (1976) Internal pH of isolated chromaffn vesicles. J Biol Chem 251:2189–2191
Johnson RG, Carty SE, Hayflick S, Scarpa A (1982) Mechanisms of accumulation of tyramine, metaraminol and isoproterenol in isolated chromaffin granules and ghosts. Biochem Pharmacol 31:815–823
Keller B, Graefe K-H (1979) The inhibitory effect of some monovalent cations on the stimulation by Na+ of the neuronal uptake of noradrenaline. Naunyn-Schmiedeberg's Arch Pharmacol 309:89–97
Langeloh A (1986) The mechanism of action of indirectly acting sympathomimetic amines. Naunyn-Schmiedeberg's Arch Pharmacol 332:R75
Langeloh A, Trendelenburg U (1987) The mechanism of the 3H-noradrenaline releasing effect of various substrates of uptake1; role of monoamine oxidase and of vesicularly stored 3H-noradrenaline. Naunyn-Schmiedeberg's Arch Pharmacol 336:611–620
Mack F, Bönisch H (1979) Dissociation constants and lipophilicity of catecholamines and related compounds. Naunyn-Schmiedeberg's Arch Pharmacol 310:1–9
Paton DM (1973) Evidence for carrier-mediated efflux of noradrenaline from the axoplasm of adrenergic nerves in rabbit atria. J Pharm Pharmacol 25:265–267
Phillips JH (1982) Dynamic aspects of chromaffm granule structure. Neuroscience 7:1595–1609
Sammet S, Graefe K-H (1979) Kinetic analysis of the interaction between noradrenaline and Na+ in neuronal uptake: kinetic evidence of co-transport. Naunyn-Schmiedeberg's Arch Pharmacol 309:99–107
Schömig E, Trendelenburg U (1987) Simulation of outward transport of neuronal 3H-noradrenaline with the help of a two-compartment model. Naunyn-Schmiedeberg's Arch Pharmacol 336:631–640
Snedecor GW, Cochran WG (1980) Statistical methods, 7th edn. Iowa State University Press, Ames
Stute N, Trendelenburg U (1984) The outward transport of axoplasmic noradrenaline induced by a rise of the sodium concentration in the adrenergic nerve endings of the rat vas deferens. Naunyn-Schmiedeberg's Arch Pharmacol 327:124–132
Thoa NB, Wooten GF, Axelrod J, Kopin IJ (1975) On the mechanism of release of norepinephrine from sympathetic nerves induced by depolarizing agents and sympathomimetic drugs. Mol Pharmacol 11:10–18
Thoenen H, Hürlimann A, Haefely W (1968) Mechanism of amphetamine accumulation in the isolated perfused heart of the rat. J Pharm Pharmacol 20:1–11
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This study was supported by the Deutsche Forschungsgemeinschaft (Bo 521, Tr 96 and SFB 176). Some of the results were presented to the German Pharmacological Society (Langeloh 1986)
A. L. was the recipient of a fellowship of the Humboldt-Foundation
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Langeloh, A., Bönisch, H. & Trendelenburg, U. The mechanism of the 3H-noradrenaline releasing effect of various substrates of uptake1: multifactorial induction of outward transport. Naunyn-Schmiedeberg's Arch Pharmacol 336, 602–610 (1987). https://doi.org/10.1007/BF00165750
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DOI: https://doi.org/10.1007/BF00165750