Vasorelaxant Activity of AP39, a Mitochondria-Targeted H₂S Donor, on Mouse Mesenteric Artery Rings In Vitro

Mitochondria-targeted hydrogen sulfide (H₂S) donor compounds, such as compound AP39, supply H₂S into the mitochondrial environment and have shown several beneficial in vitro and in vivo effects in cardiovascular conditions such as diabetes and hypertension. However, the study of their direct vascular effects has not been addressed to date. Thus, the objective of the present study was to analyze the effects and describe the mechanisms of action of AP39 on the in vitro vascular reactivity of mouse mesenteric artery. Protein and gene expressions of the H₂S-producing enzymes (CBS, CSE, and 3MPST) were respectively analyzed by Western blot and qualitative RT-PCR, as well the in vitro production of H₂S by mesenteric artery homogenates. Gene expression of CSE and 3MPST in the vessels has been evidenced by RT-PCR experiments, whereas the protein expression of all the three enzymes was demonstrated by Western blotting experiments. Nonselective inhibition of H₂S-producing enzymes by AOAA abolished H₂S production, whereas it was partially inhibited by PAG (a CSE selective inhibitor). Vasorelaxation promoted by AP39 and its H₂S-releasing moiety (ADT-OH) were significantly reduced after endothelium removal, specifically dependent on NO-cGMP signaling and SK_Ca channel opening. Endogenous H₂S seems to participate in the mechanism of action of AP39, and glibenclamide-induced K_ATP blockade did not affect the vasorelaxant response. Considering the results of the present study and the previously demonstrated antioxidant and bioenergetic effects of AP39, we conclude that mitochondria-targeted H₂S donors may offer a new promising perspective in cardiovascular disease therapeutics.