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Beta-adrenergic modulation of FMLP- and zymosan-induced intracellular and extracellular oxidant production by
S Kopprasch1, A Gatzweiler, J Graessler
1Technical University of Dresden, Carl Gustav Carus Medical School, Department of Internal Medicine III, Germany.
Abstract:
Evaluation of catecholamine modulation of PMNL extracellular and intracellular oxidant production may reflect beneficial and harmful effects of beta-adrenergic agonists in various disease states. We investigated the kinetics and potency of adrenaline-mediated inhibition of oxidant generation in FMLP- and zymosan-stimulated PMNLs. In FMLP-stimulated cells, the short-term burst of oxidant generation was inhibited by adrenaline in a dose-dependent fashion. Intra- and extracellular chemiluminescence and extracellular superoxide anion and hydrogen peroxide generation showed similar IC50 values for adrenaline (1.3-3.0 x 10(-8) M) indicating that both extracellular and intracellular events were inhibited with the same potency. In contrast, intracellular oxidant production evoked by the phagocytosis of zymosan was only minimally affected by 3 x 10(-5) -3 x 10(-12) M adrenaline. Extracellular inhibition of oxidant production was also apparent in zymosan-stimulated cells. In conclusion, adrenaline's ability to depress extracellular generation of oxygen metabolites while retaining prolonged intracellular oxidant production for phagocytosis supports its beneficial role as selectively targeted physiological protector.
Insights
Adrenaline inhibits oxidant production in polymorphonuclear leukocytes (PMNLs), particularly extracellularly. This selective action suggests a protective role for adrenaline in certain conditions.
Area of Science:
- Immunology
- Pharmacology
- Cell Biology
Background:
- Catecholamines, like adrenaline, can modulate polymorphonuclear leukocyte (PMNL) oxidant production, with potential dual effects in disease.
- Understanding the precise mechanisms of adrenaline's impact on PMNLs is crucial for evaluating beta-adrenergic agonist therapies.
Purpose of the Study:
- To investigate the kinetics and potency of adrenaline-mediated inhibition of oxidant generation in FMLP- and zymosan-stimulated PMNLs.
- To differentiate the effects of adrenaline on extracellular versus intracellular oxidant production.
Main Methods:
- Stimulation of PMNLs with formyl-methionyl-leucyl-phenylalanine (FMLP) and zymosan.
- Measurement of intra- and extracellular chemiluminescence.
- Quantification of extracellular superoxide anion and hydrogen peroxide generation.
- Dose-response analysis to determine IC50 values for adrenaline.
Main Results:
- Adrenaline dose-dependently inhibited short-term oxidant generation in FMLP-stimulated PMNLs.
- Similar IC50 values for adrenaline were observed for intra- and extracellular chemiluminescence and extracellular oxidant generation, indicating uniform potency.
- Intracellular oxidant production during zymosan phagocytosis was minimally affected by adrenaline.
- Adrenaline significantly inhibited extracellular oxidant production in zymosan-stimulated PMNLs.
Conclusions:
- Adrenaline selectively depresses extracellular oxidant generation while preserving intracellular oxidant production necessary for phagocytosis.
- This selective action supports a beneficial role for adrenaline as a targeted physiological protector.