ANALYSIS OF NANOMOLAR S-NITROSOTHIOL CONCENTRATIONS IN PHYSIOLOGICAL MEDIA

S-Nitrosothiols occur endogenously and are thought to function as stor age forms and/or stable carriers of nitric oxide. Moreover, the S-nitr osothiols have been postulated to function as neurotransmitters and me diate the vasodilator action of glyceryl trinitrate. Because of the in creasing pharmacological and physiological interest in S-nitrosothiols , a sensitive method for analysis of these substances is required. We describe a sensitive method based on adsorptive stripping voltammetry for measurement of two S-nitrosothiols, namely, S-nitroso-N-acetyl-D-p enicillamine (SNAP) and S-nitrosoglutathione (SNOG), in Krebs' solutio n. The method is based on the irreversible electrochemical reduction o f SNAP and SNOG at the hanging mercury drop electrode (HMDE). The anal ytes were adsorbed at the HMDE for 60 s at -0.100 V, then exposed to a cathodic linear potential scan of 100 mV s(-1) which resulted in the reduction of SNAP at -0.470 V and SNOG at -0.530 V. Under these condit ions, 4 nM SNAP and 11 nM SNOG were readily quantified. Using the abov e method, we were able to confirm the rapid degradation of SNAP under UV irradiation. Reproducibility of the method as applied to the analys is of these S-nitrosothiols in Krebs' solution was demonstrated by the within-day and day-to-day coefficients of variation of 1.5% and 2.0%, respectively. (C) 1998 Elsevier Science Inc.