Production of oxygen-centered radicals by neutrophils and macrophages as studied by electron spin resonance (ESR)
Neutrophils and macrophages undergo a respiratory burst and an increase in the activity of the hexose monphosphate pathway in response to particulate or soluble agents. The increase in oxygen consumption was found to be associated with the production of oxygen-centered radicals. The ESR technique of spin trapping showed that besides a superoxide spin adduct, a hydroxyl spin adduct is also produced. ESR is considered to be the least ambiguous technique for the detection of free radicals. The spin-trapping agents used for oxygen-centered radical detection are usually nitrones. The most commonly used nitrone is 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), which reacts with O/sub 2/ to form 5,5-dimethyl-2-hydroperoxypyrroline-N-oxide (DMPO-OOH) and with OH to form 5,5-dimethyl-2-hydroxypyrroline-N-oxide (DMPO-OH). Although spin-adduct formation is considered to be the most direct technique for the detection of free radicals, some disadvantages are encountered. There has been considerable interest in the isolation of the O/sub 2/ generating activity from phagocytic cells. The enzyme can be extracted with deoxycholate and gel filtration indicates that it is a high molecular weight complex. Maximum activity was between pH 7.0 and pH 7.5. The K/sub m/ value was 15.8 ..mu..M for NADPH and 434 ..mu..m for NADH, indicating that NADPH is the preferred substrate. 73 references.
- Research Organization:
- Univ. of Oxford, England
- OSTI ID:
- 5217425
- Journal Information:
- Environ. Health Perspect.; (United States), Journal Name: Environ. Health Perspect.; (United States) Vol. 64; ISSN EVHPA
- Country of Publication:
- United States
- Language:
- English
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADDUCTS
ANGULAR MOMENTUM
ANIMAL CELLS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BIOLOGICAL PATHWAYS
BLOOD
BLOOD CELLS
BODY FLUIDS
CHEMICAL ACTIVATION
COENZYMES
CONNECTIVE TISSUE CELLS
ELECTRON SPIN RESONANCE
ENZYME ACTIVITY
HYDROXYL RADICALS
KINETICS
LEUKOCYTES
MACROPHAGES
MAGNETIC RESONANCE
MATERIALS
MOLECULAR WEIGHT
NADP
NEUTROPHILS
NUCLEOTIDES
ORGANIC COMPOUNDS
PARTICLE PROPERTIES
PARTICLES
PARTICULATES
PH VALUE
PHAGOCYTES
RADICALS
REACTION KINETICS
RESONANCE
RESPIRATION
SOMATIC CELLS
SPIN
SUPEROXIDE RADICALS