Hydrogen Sulphide Is Involved in Testosterone Vascular Effect

BackgroundTestosterone (T) induces a rapid relaxation in vascular tissues of different species due to a nongenomic effect of this steroid on vessels. Different mechanisms have been proposed to explain T-induced vasodilatation but the effective mechanism(s) and the mediators involved are still a matter of debate.ObjectivesWe have evaluated if H2S pathway is involved in T vascular effects.Design and settingMale Wistar rats were sacrificed and thoracic aorta was rapidly dissected and cleaned from fat and connective tissue. Rings of 2–3 mm length were cut and placed in organ baths filled with oxygenated Krebs solution at 37 °C and mounted to isometric force transducers. H2S determination was performed on thoracic aortic rings incubated with T or vehicle and in presence of inhibitors. H2S concentration was calculated against a calibration curve of NaHS (3–250 μM). Results were expressed as nmoles/mg protein.MeasurementsVascular reactivity was evaluated by using isometric transducers. H2S determination was performed by using a cystathionine β-synthetase (CBS) and cystathionine γ lyase (CSE) activity assay. CSE and CBS protein levels were assessed by Western blot analysis. Statistical analysis was performed by using two-way ANOVA and unpaired Student's t-test where appropriate.ResultsT significantly increased conversion of L-cysteine to H2S. This effect was significantly reduced by PGG and BCA, two specific inhibitors of CSE. T (10 nM–10 μM) induced a concentration-dependent vasodilatation of rat aortic rings in vitro that was significantly and concentration-dependent inhibited by PGG, BCA, and glybenclamide. Incubation of aorta with T up to 1 h did not change CBS/CSE expression, suggesting that T modulates enzymatic activity.ConclusionsHere we demonstrate that T vasodilator effect involves H2S, a novel gaseous mediator. T modulates H2S levels by increasing the enzymatic conversion of L-cysteine to H2S.