Effect of hydrogen sulfide on vasorelaxation and content of guanosine 3', 5'-cyclic phosphate in vascular tissue of rats

Abstract

Objective To observe the effect of hydrogen sulfide (H2S) on vasorelaxation and expression of guanosine 3', 5'-cyclic phosphate (cGMP) and activity of cyclic nucleotide phosphodiesterase (PDE) in vascular tissue. Methods H2S donor was provided by sodium bisulfide sodium hydrosulfide.The isolated perfused rat thoracic aorta rings were used to test the relaxation responses to H2S, which recorded by Power Lab system, and the enzyme-linked immuno assay was used to detect intracellular cGMP.The activity of PDE was evaluated by using cyclic nucleotide PDE assay kit. Results (1)H2S relaxed the thoracic aorta rings, and the half maximal effective concentration (EC50) for the H2S relaxation curve, represented by the corresponding concentration of H2S that achieved 50% of the maximum relaxation effect, was (1.79±0.31)×10-5 mol/L.(2)The cGMP content in vascular tissue increased from(22.29±1.59) pmol/L to(41.45±7.49) pmol/L and (31.35±2.56) pmol/L after incubation with 50 μmol/L and 300 μmol/L H2S, respectively (t= -3.09, t=-2.88; all P<0.05, n=7-8). (3)cGMP could be lysed into 5'-guanylicacid(5'-GMP) by PDE, which was an important pathway for cGMP degradation.This study showed that PDE activity was decreased in vascular tissue, the 5'-GMP decreased from (0.52±0.06) mol/L to (0.25±0.06) mol/L and (0.27±0.07) mol/L after incubation with 50 μmol/L and 300 μmol/L H2S, respectively (t=3.21, t=2.58; all P<0.05, n=7-8). Conclusion The vasorelaxant effects of H2S might be related to the inhibited activity of PDE and elevated content of cGMP. Key words: Hydrogen sulfide; Guanosine 3', 5'-cyclic phosphate; Cyclic nucleotide phosphodiesterase; Vasorelaxation