Light elements quantification in stimulated cells cryosections studied by electron probe microanalysis

The quantification of intracellular light elements such as carbon, nitrogen and oxygen may be useful in understanding the biological mechanisms, for example the generation of nitric oxide which is involved in apoptosis and inflammatory reaction. Electron energy loss spectroscopy (EELS) coupled with scanning transmission electron microscopy is a useful method to detect light elements in thin cryosections. Recent developments of X-ray detectors with ultra-thin protection windows allows the detection of such elements by energy dispersive X-ray spectroscopy, In the present study. we have demonstrated using both methods that the stimulation of BV-2 murine microglial cell line by gamma-interferon and lipopolysaccharide leads to the increase of intracellular oxygen concentration and no change in the intracellular nitrogen concentration. This indicates the use of exogeneous molecular oxygen in response to the stimulation. But the increase of oxygen concentration detected could not be only due to NO expression because the NO production was 1000 times less than the oxygen concentration increase observed. (C) 2002 Elsevier Science Ltd. All rights reserved.