Fig 1. In vitro release of gaseous H₂S from ATTM and NaHS under different environmental conditions.

Comparison of ammonium tetrathiomolybdate (ATTM) and NaHS with changes in (A) concentration and (B) time. In (A), the molarity of each compound was adjusted for equal total sulfur content; drugs were incubated for 1 h at physiological pH (7.4) and temperature (37°C). In (B), fixed concentrations were used: ATTM 100 mM (total sulfur) and NaHS 0.3 mM. The effects of pH, temperature, and the presence of thiols on H₂S gas released from ATTM are shown in (C–E). Here, fixed concentrations (100 mM total sulfur) and incubation time (1 h) were employed. Peak H₂S concentrations are displayed in parts per million (ppm). The thiols used were reduced glutathione (GSH; 5 mM) and L-cysteine (Cys; 5 mM). The dotted lines reflect typical H₂S gas levels (3–4 ppm) obtained from ATTM (100 mM total sulfur) following 1 h incubation at normal physiological pH and temperature. n = 3–6 per group.