Fig. 6.
(A, B) Effects of combinations of H2S (300 μM), H2O2 (300 μM) and sodium azide (Az, 50 mM) with or without 10 μM (A) or 40 μM (B) catalase (Cat) on putative polysulfide production measured by SSP4 fluorescence. H2S in combination with either H2O2 or H2O2 + azide produced the greatest increase in fluorescence. Low (10 μM) catalase produced a small amount of fluorescence from H2S. Conversely, substantial fluorescence was produced by H2S and 40 μM catalase. H2O2 did not significantly increase fluorescence production from H2S and 40 μM catalase, whereas fluorescence was decreased by azide. Catalase alone did not affect SSP4 fluorescence. (C, D) Effects of combinations of the mixed polysulfide H2Sn (PS; 300 μM), H2O2 (300 μM) and sodium azide (50 mM) with or without 10 μM (C) or 40 μM (D) catalase on SSP4 fluorescence. In the absence of catalase, polysulfide alone produced the greatest increase in fluorescence and fluorescence was decreased by H2O2 alone and to the same extent by H2O2 plus azide. Polysulfide fluorescence was reduced by more than 80% by 10 μM catalase and completely eliminated by 40 μM catalase. The inhibitory effect of catalase was unaffected by addition of H2O2, azide or H2O2 plus azide. Traces of SSP4 or SSP4 plus catalase did not affect fluorescence and have been omitted for clarity. Mean +SE, n =4, many error bars are within symbols. The difference in total fluorescence in A, B or C, D was due to different lot numbers of SSP4.