Acta Pharmacologica Sinica 2006 December; 27 (12): 1561-1566; doi: 10.1111/j.1745-7245.2006.00425.x

Aim: To investigate the interaction between hydrogen sulfide (H₂S)/cystathionine γ-lyase (CSE) and carbon monoxide (CO)/heme oxygenase (HO) pathways in aortic smooth muscle cells (ASMC).

Methods: The ASMCs were divided into the following groups: (1) the control group; (2) the zinc protoporphyrin (ZnPP) 20 µmol/L group; (3) the propargylglycine (PPG) 2 mmol/L, 4 mmol/L and 10 mmol/L groups; and (4) the sodium hydrosulfide (NaHS) 1×10^-5 mol/L, 1×10^-4 mol/L and 1×10^-3 mol/L groups. Each of the groups was further divided into 6 h, 12 h, 18 h and 24 h subgroups. The CO level, represented by carboxyhemoglobin (HbCO) content was measured using a spectrophotometric method and H₂S content was detected by a sensitive electrode method. CSE and HO-1 expressions were detected by Western blotting.

Results: The H₂S content in the medium and CSE expression by ASMC were markedly increased by ZnPP compared with the control group. HbCO content in the medium and HO-1 expression by the ASMC started strengthening following 24 h treatment with PPG at 2 mmol/L, but were further strengthened following 18 h and 24 h treatment with PPG at 4 mmol/L compared with the controls (P<0.01). PPG at 10 mmol/L increased the HbCO level in the medium following 18 h treatment and increased HO-1 expression by the ASMC following 12 h treatment. Moreover, NaHS at 1×10^-5 mol/L and 1×10^-4 mol/L decreased the HbCO level in the medium and HO-1 expression by the ASMC after 6 h and 12 h treatment, while NaHS at 1×10^-3 mol/L decreased them at all time points of the treatments.

Conclusion: The results suggested that endogenous CO/HO and H₂S/CSE pathways inhibited each other in ASMC under physiological conditions.

Keywords: hydrogen sulfide; cystathionine γ-lyase; carbon monoxide; heme oxygenase