Abstract
Previous pharmacological studies have demonstrated that pulmonary endothelial cells and noradrenergic neurones possess the same transporter for inward transport of catecholamines, uptake1. In noradrenergic neurones, it has been shown that uptake1 is also involved in the carrier-mediated outward transport, or efflux, of noradrenaline and dopamine. The aim of the present study was to examine the efflux of noradrenaline and dopamine from perfused lungs of rats to determine whether uptake1, in addition to diffusion, mediates efflux of catecholamines from pulmonary vascular endothelial cells.
The effects of reducing the cellular sodium gradient and of substrates and inhibitors of uptake1 on the efflux of 3H-noradrenaline and 3H-dopamine from rat lungs were measured. Isolated; perfused lungs of rats (monoamine oxidase and catechol-0-methyltransferase inhibited) were loaded with 3H-(−)noradrenaline or 3H-dopamine for 10 min followed by perfusion with either (1) a low sodium, amine-free: Krebs solution, in which NaCl was replaced by either Tris.HCl or LiCl, for 15 or 10 min, respectively or (2) amine-free Krebs solution for 30 min in the absence or presence of a substrate or inhibitor of uptake1 for the last 15 min. The rate constants for spontaneous efflux of noradrenaline and dopamine from the lungs were 0.0163 min−1 and 0.0466 min−1, respectively. When NaCl was replaced by Tris.HCl during efflux, the rate constants for efflux of noradrenaline and dopamine were increased 2.5-fold and 3-fold, respectively, whereas, when NaCl was replaced by LICl, the rate constants were increased 8-fold and 4-fold, respectively. The uptake1 substrates, dopamine (1 and 3 μmol/l) and adrenaline (40 μmol/l), both caused a rapid and marked increase in the efflux of noradrenaline, while noradrenaline (4 μmol/l) had a similar effect on the efflux of dopamine. The uptake 1 inhibitors, imipramine (3 and 10 μmol/l) and nisoxetine (50 nmol/l), caused small and gradual increases in the efflux of noradrenaline and dopamine from rat lungs.
These results demonstrate that efflux of noradrenaline and dopamine from rat lungs is affected by alterations in the normal sodium gradient across the cell and by drugs that interact with the uptake1 transporter. Thus, it can be concluded that the spontaneous efflux of catecholamines from pulmonary vascular endothelial cells is mediated predominantly by uptake1. In addition, efflux of catecholamines from the lungs has a diffusional component, which, combined with inhibition of reuptake, accounts for the small increase in amine efflux by inhibitors of uptake1.
Similar content being viewed by others
Abbreviations
- COMT:
-
Catechol-O-methyltransferase
- FRL:
-
Fractional rate of loss
- K m :
-
Michaelis or half-saturation constant
- t out :
-
rate constant for efflux
- k uptake :
-
rate constant for uptake
- MAO:
-
monoamine oxidase
- t /12 :
-
half-time for efflux
- U-0521:
-
3′,4′-dihydroxy-2-methylpropiophenone
- V max :
-
maximal rate of uptake
References
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, 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
Bryan-Lluka LJ, O'Donnell SR (1991) Isolated perfused lungs of guinea-pig, in contrast with rat, lack an uptake process for noradrenaline. Pulm Pharmacol 4:146–150
Bryan-Lluka LJ, O'Donnell SR (1992) Dopamine and adrenaline, but not isoprenaline, are substrates for uptake and metabolism in isolated perfused lungs of rats. Naunyn-Schmiedeberg's Arch Pharmacol 346:20–26
Bryan-Lluka LJ, Westwood NN, O'Donnell SR (1992) Vascular uptake of catecholamines in perfused lungs of the rat occurs by the same process as Uptake1 in noradrenergic neurones. Naunyn-Schmiedeberg's Arch Pharmacol 345:319–326
Bryan-Lluka LJ, Seers H, Sharpe I (1996) Amezinium and debrisoquine are substrates of uptake1 and potent inhibitors of monoamine oxidase in perfused lungs of rats. Naunyn-Schmiedeberg's Arch Pharmacol 353:536–544
Graefe K-H, Bönisch H (1988) The transport of amines across the axonal membranes of noradrenergic and dopaminergic neurones. In: Trendelenburg U, Weiner N (eds) Handbook of experimental pharmacology, 90: catecholamines, vol I. Springer, Berlin Heidelberg New York, pp. 193–245
Henseling M, Eckert E, Trendelenburg U (1976) The distribution of 3H-( ± )-noradrenaline in rabbit aortic strips after inhibition of the noradrenaline-metabolizing enzymes. Naunyn-Schmiedeberg's Arch Pharmacol 292:205–217
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, Bönisch H, Trendelenburg U (1987) 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
Langeloh A, Halbrügge T, Trendelenburg U (1991) Carrier-mediated outward transport of dopamine from adrenergic varicosities of the vas deferens of reserpine-pretreated rats. Naunyn-Schmiedeberg's Arch Pharmacol 344:619–622
Mack F, Bönisch H (1979) Dissociation constants and lipophilicity of catecholamines and related compounds. Naunyn-Schmiedeberg's Arch Pharmacol 310:1–9
Nicholas TE, Strum JM, Angelo LS, Junod AF (1974) Site and mechanism of uptake of 3H-l-norepinephrine by isolated perfused rat lungs. Circ Res 35:670–680
Ross SB, Kelder D (1979) Release of 3H-noradrenaline from the rat vas deferens under various in vitro conditions. Acta Physiol Scand 105:338–349
Sammet S, Graefe K-H (1979) Kinetic analysis of the interaction between noradrenaline and Na+ in neuronal uptake:kinetic evidence for co-transport. Naunyn-Schmiedeberg's Arch Pharmacol 309:99–107
Scarcella DL, Westwood NN, Bryan-Lluka LJ (1993) Efflux of catecholamines from rat lungs occurs by uptake1. Clin Exp Pharmacol Physiol Suppl 1:65
Schömig E, Fischer P, Schönfeld C-L, Trendelenburg U (1989) The extent of neuronal re-uptake of 3H-noradrenaline in isolated vasa deferentia and atria of the rat. Naunyn-Schmiedeberg's Arch Pharmacol 340:502–508
Snedecor GW, Cochran WG (1989) Statistical Methods, 8th edn. Iowa State University Press, Ames
Stefano FJE, Trendelenburg U (1984) Saturation of monoamine oxidase by intraneuronal noradrenaline accumulation. Naunyn-Schmiedeberg's Arch Pharmacol 328:135–141
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
Trendelenburg U (1988) The extraneuronal uptake and metabolism of catecholamines. In: Trendelenburg U, Weiner N (eds) Handbook of experimental pharmacology, 90:catecholamines, vol I. Springer, Berlin Heidelberg New York, pp. 279–319
Author information
Authors and Affiliations
Additional information
Preliminary results of this study were presented to the 1993 Meeting of the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists (Scarcella et al. 1993).
Rights and permissions
About this article
Cite this article
Westwood, N.N., Scarcella, D.L. & Bryan-Lluka, L.J. Evidence for uptake1-mediated efflux of catecholamines from pulmonary endothelial cells of perfused lungs of rats. Naunyn-Schmiedeberg's Arch Pharmacol 353, 528–535 (1996). https://doi.org/10.1007/BF00169172
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00169172