Superoxide release from interleukin-1B-stimulated human vascular cells: Insitu electrochemical measurement

Release of superoxide anion by cultured vascular cells was investigated wit h the use of selective microelectrodes. Local concentration of superoxide a nion (O-2(.-)) was followed by differential pulse amperometry on a carbon m icrofiber at 0.1 V/SCE. The oxidation current allows O-2(.-) detection in t he 10(-8) M concentration range without interference of the other major oxy gen species. Interleukin-1 beta-stimulated O-2(.-) release that progressive ly increased to reach local concentrations at the cell membrane level of 76 +/- 11 nm 40-60 min after stimulation in human cord vein endothelial cells , and 131 +/- 18 nm 1-2 h after stimulation in internal mammary artery smoo th muscle cells. In the two types of cells, the O-2(.-) oxidation signal wa s suppressed in the presence of superoxide dismutase. Spontaneous O-2(.-) r elease from unstimulated cells was undetectable. These results demonstrate that selective microelectrodes allow direct and real-time monitoring of loc al O-2(.-) released from vascular endothelial as well as from smooth muscle cells submitted to an inflammatory stimulus. (C) 1999 Elsevier Science Inc .