RESUMO
1. Nitric oxide (NO) production in C6 glioma cells was directly monitored in real time by electrochemical detection with a NO-specific biosensor. 2. We present here the first direct evidence that noradrenaline elicits long-lasting NO production in C6 cells pretreated with lipopolysaccharide and interferon-gamma, an effect blocked by NG-monomethyl-L-arginine, a NO synthase inhibitor. 3. This direct electrochemical measurement of glia-derived NO should facilitate our understanding of the kinetics of glial signaling in glia-glia and glia-neuron networks in the brain.
Assuntos
Óxido Nítrico/biossíntese , Norepinefrina/farmacologia , Animais , Arginina/farmacologia , Técnicas Biossensoriais , Encéfalo/fisiologia , Eletroquímica/métodos , Glioma , Interferon gama/farmacologia , Lipopolissacarídeos/farmacologia , Neurônios/fisiologia , Óxido Nítrico/análise , Transdução de Sinais , Células Tumorais Cultivadas , ômega-N-Metilarginina/farmacologiaRESUMO
We describe here the electrochemical detection of nitric oxide, NO, in biological systems by using chemically modified ultramicro carbon electrodes. In the first part of the paper, the different steps involved in the electrochemical preparation and characterization of the nickel-based sensor are described. This is illustrated by the use of nickel(II) tetrasulfonated phthalocyanine complex. The second part of the paper describes two examples of the direct electrochemical measurement of NO production in human blood platelets and endothelial cells from umbilical cord vein.
Assuntos
Técnicas Biossensoriais , Óxido Nítrico/análise , Plaquetas/metabolismo , Células Cultivadas , Meios de Cultura/química , Eletroquímica/instrumentação , Eletroquímica/métodos , Endotélio Vascular/metabolismo , Humanos , Técnicas In Vitro , Níquel , Óxido Nítrico/biossínteseRESUMO
We describe in this paper an electrochemical and spectrophotometric study of the behavior of an electropolymerized nickel porphyrin film as a sensor for the determination of nitric oxide (NO) in aqueous solution. Our results show that the anodic oxidation of NO at the modified electrode may not be the result of a catalytic effect induced by the porphyrinic complex. However, the current (measured by differential pulse amperometry) and calculated NO concentration showed a linear relationship in the range 15 nM-6 muM in aerobic phosphate buffer solution (pH 7.4). These results provide a fruitful example of calibration of such electrochemical sensors for the selective detection of NO with a calculated detection limit, at a signal-to-noise ratio of three, equal to 1.5 nM.