Affiliation:
1. Department of Pharmacology, Faculty of Pharmacy University of Belgrade Belgrade Serbia
2. Faculty of Medicine University of Belgrade Belgrade Serbia
3. Institute for Cardiovascular Diseases “Dedinje” Belgrade Serbia
4. Serbian Academy of Sciences and Arts Belgrade Serbia
5. Center for Basic Medical Research & Department of Cardiovascular Surgery TEDA International Cardiovascular Hospital Tianjin China
6. Department of Surgery Oregon Health and Science University Portland Oregon USA
Abstract
AbstractBackgroundChanges in K+ channel expression/function are associated with disruption of vascular reactivity in several pathological conditions, including hypertension, diabetes, and atherosclerosis. Gasotransmitters achieve part of their effects in the organism by regulating ion channels, especially K+ channels. Their involvement in hydrogen sulfide (H2S)‐mediated vasorelaxation is still unclear, and data about human vessels are limited.ObjectiveTo determine the role of K+ channel subtypes in the vasorelaxant mechanism of H2S donor, sodium‐hydrosulfide (NaHS), on isolated human internal mammary artery (HIMA).ResultsNaHS (1 × 10−6–3 × 10−3 mol/L) induced a concentration‐dependent relaxation of HIMA pre‐contracted by phenylephrine and high K+. Among K+ channel blockers, iberiotoxin, glibenclamide, 4‐aminopyridine (4‐AP), and margatoxin significantly inhibited NaHS‐induced relaxation of phenylephrine‐contracted HIMA (P < 0.01), whereas in the presence of apamin/1‐[(2‐chlorophenyl) diphenylmethyl]‐1H‐pyrazole (TRAM‐34) combination, the HIMA relaxation was partially reduced (P < 0.05). The effect of NaHS was antagonized by NO pathway inhibitors, L‐NAME and KT5823, and by cyclo‐oxygenase inhibitor, indomethacin (P < 0.01). Under conditions of blocked NO/prostacyclin synthesis and release, apamin/TRAM‐34 and glibenclamide caused further decrease in NaHS‐induced vasorelaxation (P < 0.01), while iberiotoxin, 4‐AP, and margatoxin were without additional effect (P > 0.05). In the presence of nifedipine, NaHS induced partial relaxation of HIMA (P < 0.01).ConclusionOur results demonstrated that H2S donor, NaHS, induced concentration‐dependent relaxation of isolated HIMA. Vasorelaxant mechanisms of H2S included direct or indirect opening of different K+ channel subtypes, KATP, BKCa, SKCa/IKCa, and KV (subtype KV1.3), in addition to NO pathway activation and interference with extracellular Ca2+ influx.