Figure 3.

The proportion of H₂³⁵S delivered to colonic muscularis externa incubated with vehicle (0.1% EtOH) or 3 µM stigmatellin that was recovered as either [³⁵S]-sulphate, [³⁵S]-thiosulphate or H₂³⁵S or all three of these molecules. Nearly all of the supplied H₂³⁵S was recovered as H₂³⁵S when added to syringes containing the incubation solution without tissue (solution alone). The presence of tissue reduced the proportion of supplied H₂³⁵S recovered as H₂³⁵S and increased the proportion of H₂³⁵S recovered as [³⁵S]-sulphate and [³⁵S]-thiosulphate (*P < 0.05 compared with solution alone, Kruskal–Wallis test followed by Dunn's test). Stigmatellin (3 µM) increased the proportion of H₂³⁵S recovered as H₂³⁵S (†P < 0.05 compared with tissue with vehicle, Kruskal–Wallis test followed by Dunn's test) and decreased the proportion of H₂³⁵S recovered as [³⁵S]-thiosulphate (‡P < 0.05 compared with tissue with vehicle, Mann–Whitney U-test) but did not affect the proportion of H₂³⁵S recovered as [³⁵S]-sulphate (P > 0.05 compared with tissue with vehicle, Kruskal–Wallis test and Mann–Whitney U-test). Data are the mean ± SEM proportions for 8–12 observations.