A fluorescence method for the determination of plasma susceptibility to lipid peroxidation.

ABSTRACT

OBJECTIVE: We propose a fluorescence kinetics method for monitoring plasma susceptibility to peroxidation. DESIGN AND METHOD: Plasmatic peroxidation was induced by CuSO4 (500 microM), and fluorescence was measured every 30 min. Kinetics were represented by a sigmoidal curve from which it was possible to calculate the latency time (lag-time) and the propagation velocity (slope) of plasma peroxidation. RESULTS: The lag-time monitored by the fluorescence kinetics method corresponded to the formation of thiobarbituric acid reactive substances, and to progressive depletion of polyunsaturated fatty acids and alpha-tocopherol. The mechanism of reaction appeared to be dependent upon plasmatic hydroperoxides, and independent of oxygen radicals. Plasma storage is possible for at least two months at -80 degrees C, and reproducibility of the method is very good. CONCLUSIONS: Fluorescence kinetics provide a highly comprehensive picture of plasma susceptibility to peroxidation in comparison with the conventional measurements of anti- and pro-oxidant ratios.