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A neutrophil-derived NO-synthase (NOS) inhibitor
A Dembinska-Kiec1, M Burchert, J Hartwich
1Department of Clinical Biochemistry, Collegium Medicum, Jagiellonian University, Cracow, Poland.
Agents and Actions. Supplements
|January 1, 1995
Summary
A novel endogenous inhibitory factor reduces nitric oxide synthase (NOS) activity in neutrophils. This factor also inhibits constitutive NOS (cNOS) and inducible NOS (iNOS), with inhibition reversed by L-arginine.
Area of Science:
- Biochemistry
- Immunology
- Neuroscience
Background:
- Nitric oxide synthase (NOS) plays a critical role in various physiological processes.
- Reduced NOS activity in circulating neutrophils has been observed but not fully explained.
Purpose of the Study:
- To identify and characterize an endogenous factor responsible for inhibiting NOS activity in neutrophils.
Main Methods:
- Assay of NOS activity in neutrophils.
- Testing the inhibitory effects of a purified endogenous factor on constitutive NOS (cNOS) and inducible NOS (iNOS).
- Investigating the effect of boiling and the reversal of inhibition by NADPH and L-arginine.
Main Results:
- An endogenous inhibitory factor was identified in neutrophils, reducing their NOS activity.
- This factor inhibited both cNOS (cerebellum) and iNOS (macrophages) in a concentration-dependent manner.
- Inhibition was partially resistant to boiling and could be reversed by L-arginine and NADPH.
Conclusions:
- Circulating neutrophils possess low NOS activity due to an endogenous inhibitory factor.
- This factor represents a novel regulator of NOS activity, impacting both constitutive and inducible isoforms.
- Understanding this inhibitor may offer new therapeutic targets for conditions involving NOS dysregulation.