Adenosine and guanosine phosphorothioates (AMPS and GMPS) are synthetic nucleotide analogues that contain one sulfur atom instead of oxygen attached to the phosphorus atom. Previously, it has been demonstrated that histidine triad nucleotide-binding protein-1 (Hint-1) – the ubiquitously expressed nuclear protein – enzymatically decomposes AMPS and GMPS to H 2 S and AMP or GMP, respectively, in cell-free systems [1] , [2] . In addition, AMPS can enter the cell through plasma membrane ionotropic purinergic receptor P2X 7 [3] . We examined if AMPS and GMPS can be enzymatically converted to H 2 S in intact cells. The study was performed in isolated rat kidney glomeruli because endogenous H 2 S is synthesized there, and P2X 7 receptors are expressed in glomerular mesangial cells. Isolated glomeruli were incubated with AMPS or GMPS and real-time H 2 S formation was measured by the polarographic sensor. No H 2 S production was detected from either compound under baseline conditions, however, H 2 S was generated in a time- and substrate concentration-dependent manner if specific P2X 7 agonist, BzATP (10 μ M), was added. H 2 S production from AMPS or GMPS in the presence of BzATP was inhibited by P2X 7 antagonist, A-438079 (1 μ M). H 2 S formation was augmented by either hypoxic conditions (1% O 2 ) or the inhibitor of mitochondrial H 2 S oxidation, stigmatellin, and was insensitive to cystathionine γ -lyase (CSE) inhibitor, propargylglycine (PAG). No H 2 S formation was observed if AMPS or GMPS were incubated without glomeruli or when glomeruli were incubated with AMP or GMP. H 2 S production from 1 mM L-cysteine (67.3 ± 5.2 pmol/mg protein/min) was higher than from either 1 mM AMPS (27.1 ± 2.1 pmol/mg protein/min) or 1 mM GMPS (43.4 ± 4.1 pmol/mg protein/min) and was attenuated by 73% with PAG, but was insensitive to either BzATP or A-438079. AMPS, GMPS (in the absence of BzATP) as well as AMP and GMP had no effect on H 2 S production from L-cysteine. Preliminary results indicate that AMPS or GMPS are converted to H 2 S in in situ perfused rat kidney when BzATP is co-infused, which results in the increase in glomerular filtration rate (GFR) and filtration fraction. These data indicate that AMPS and GMPS may be converted to H 2 S inside the cell in CSE-independent manner but only if P2X 7 receptors are activated. Nucleoside phosphorothioates may serve as new H 2 S donors for research and possibly therapeutic purposes. The specific features of them in contrast to previously used inorganic sulfide salts or organic donors include: (i) receptor-mediated transport to the cell which may be the subject for additional regulation, (ii) enzymatic rather than chemical conversion to H 2 S, (iii) formation of endogenous, non-toxic by products: AMP or GMP.