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Endothelium‐Independent Vasorelaxation Induced by Nitric Oxide Generation from the Novel Organic Nitrate NDOP Is Partially Mediated by Inward‐Rectifier Potassium Channels
Author(s) -
Paula Ricardo B,
Montenegro Marcelo F,
FrançaSilva Maria S,
Brandão Maria C,
Diniz Thiago F,
Lemos Virginia S,
AthaydeFilho Petrônio F,
Magnani Marciane,
Lundberg Jon O,
Carlström Mattias,
Braga Valdir A
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.689.8
Subject(s) - nitric oxide , chemistry , enos , soluble guanylyl cyclase , phenylephrine , hydroxocobalamin , endothelium , peroxynitrite , nitric oxide synthase , potassium channel , vasodilation , inward rectifier potassium ion channel , medicine , pharmacology , vascular smooth muscle , endocrinology , superoxide , biochemistry , receptor , blood pressure , ion channel , cyclic gmp , organic chemistry , smooth muscle , cyanocobalamin , vitamin b12 , enzyme
Nitric oxide (NO) deficiency is crucially linked to the development and progression of cardiovascular diseases, including arterial hypertension. Here, the mechanisms underlying the vascular effects of the new organic nitrate 2‐nitrate‐1,3‐di(octanoxy)propane (NDOP), a putative nitric oxide (NO) donor, were investigated. A combination of in vitro and ex vivo approaches was used to assess the effects of NDOP on vascular reactivity and NO release in normotensive C57BL/6J mice. The intracellular fluorescent probe DAF‐2 DA revealed NDOP‐mediated NO formation in isolated vascular smooth muscle cells from mice aortae (53.2 ± 1.6 vs. 10.7 ± 0.9 a.u., n = 13, P < 0.05). The increased NO signal by NDOP was not affected by inhibition of endothelial nitric oxide synthase (eNOS). In isolated phenylephrine‐preconstricted aortic ring preparations, NDOP‐mediated vasorelaxation (10 −8 –10 −3 M) was not reduced by previous inhibition of eNOS (112.5 ± 7.4 vs. 107.3 ± 7.5%, n = 7). However, inhibition of soluble guanylyl cyclase with ODQ (22.2 ± 6.7, n = 6, P < 0.05) and treatment with the NO scavengers PTIO (75.7 ± 5.6, n=7, P < 0.05) and PTIO+hydroxocobalamin (38.8 ± 4.6, n = 4, P < 0.05) all reduced NDOP‐mediated endothelium‐independent vasorelaxation in aortae compared with control. When aortic rings were contracted with modified Krebs solution by KCl (60 mM), NDOP‐induced vasorelaxation was attenuated (80.4 ± 5.2 n = 6, P < 0.05). Non‐selective inhibition of potassium (K + ) channels using Krebs depolarizing solution (KCl 20 mM) reduced relaxation induced by NDOP (72.8 ± 3.4; n = 6, P < 0.05) suggesting the involvement of K + channels. Selective blockade of large conductance calcium‐activated potassium channels (BK ca ) by tetraethylammonium (1 mM), voltage‐gated potassium channel (K v ) by 4‐aminopyridine (1 mM) or ATP‐sensitive potassium channels (K ATP ) by glibenclamide (10 μM) did not affect relaxation induced by NDOP. However, pre‐incubation with barium chloride (30 μM), an inward‐rectifier potassium channels (K IR ) blocker reduced NDOP‐mediated vasorelaxation (73.7 ± 5.7, n = 6, P < 0.05) compared with control. Direct measurements of NO gas by chemiluminescence demonstrated dose‐dependent NO generation by NDOP (0.1 mM = 1.8 ± 0.2 ppb; 1 mM = 9.0 ± 0.8 ppb; 10 mM = 17.2 ± 2.3 ppb, n = 3), which was dependent on xanthine oxidoreductase activity. In conclusion, NDOP‐mediated vasorelaxation involves increased NO formation, which can stimulate sGC‐cGMP signaling and alter the function of inward‐rectifier potassium channels. Support or Funding Information Capes, CNPq and STINT