Publication Date:
2000-07-04
Description:
Fluorescent Nitric Oxide Cheletropic Traps (FNOCTs) were applied to specifically trap nitric oxide (NO) with high sensitivity. The fluorescent oquinoid ?electron system of the FNOCTs (? = 460 nm, ? = 600 nm) reacts rapidly with NO to a fluorescent phenanthrene system (? = 380 nm, ? = 460 nm). The cyclic nitroxides thus formed react further to nonradical products which exhibit identical fluorescence properties. Using the acid form of the trap (FNOCT-4), NO release by spermine NONOate and by lipopolysaccharide (LPS) activated alveolar macrophages were studied. A maximum extracellular release of NO of 37.5 nmol h[-1] (10[6] cells)[-1] from the macrophages was determined at 11 h after activation. Furthermore, intracellular NO release by LPSactivated macrophages and by microvascular omentum endothelial cells stimulated by the Ca[2+] ionophore A-23187, respectively, was monitored on the single cell level by means of fluorescence microscopy. After loading the cells with the membranepermeating acetoxymethylester derivative FNOCT-5,which is hydrolyzed to a nonpermeating dicarboxylate by intracellular hydrolases, NO formation by the endothelial cells started immediately upon stimulation, whereas start of NO production by the macrophages was delayed with a variation between 4 and 8 h for individual cells. These results demonstrate that the FNOCTs can be used to monitor NO release from single cells, as well as from NOdonating compounds, with high sensitivity and with temporal and spatial resolution.
Print ISSN:
1431-6730
Electronic ISSN:
1437-4315
Topics:
Biology
,
Chemistry and Pharmacology
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