Fig. 2.
Correlation between NO peak heights and DEA/NO concentrations. (A) NO time traces observed with the NO electrode with 30, 200, 400, and 1000 nM DEA/NO in the absence of GSH. (B) Peak heights observed with a range of DEA/NO concentrations between 30 nM and 1 µM (n=3). Peak heights are determined by the relative rates of NO release and NO consumption/escape. See main text and the supplementary material for details. Data were fitted (dashed lines) to the equation [NO]peak=C2·[DEA/NO]C1, in which C1 and C2 are variables. The observed value for C1 is very close to 1 (0.96±0.02), indicating a linear relationship between peak height and DEA/NO concentration. Please note that the apparent absolute correlation between observed peak heights and DEA/NO concentrations (1 µM NO for 1 µM DEA/NO) is accidental: DEA/NO can release up to 2 equivalents of NO, and observed peak heights are necessarily lower than the released NO concentrations. (C) Dependence of the time at which the NO concentration is maximal as a function of the DEA/NO concentration. See main text and the supplementary material for details. The observations suggest a first-order disappearance of NO. Experimental conditions: 1 µM DEA/NO, 4 mM CuSO4, 1000 U/ml SOD, 0.1 mM DTPA, 5 mM MgCl2, and 50 mM TEA (pH 7.4) in 0.5 ml at 37 °C.