title: Endothelium-Dependent Contractions of Isolated Arteries to Thymoquinone Require Biased Activity of Soluble Guanylyl Cyclase with Subsequent Cyclic IMP Production.
abstract: Preliminary experiments on isolated rat arteries demonstrated that thymoquinone, a compound widely used for its antioxidant properties and believed to facilitate endothelium-dependent relaxations, as a matter of fact caused endothelium-dependent contractions. The present experiments were designed to determine the mechanisms underlying this unexpected response. Isometric tension was measured in rings (with and without endothelium) of rat mesenteric arteries and aortae and of porcine coronary arteries. Precontracted preparations were exposed to increasing concentrations of thymoquinone, which caused concentration-dependent, sustained further increases in tension (augmentations) that were prevented by endothelium removal, Nω-nitro-L-arginine methyl ester [L-NAME; nitric oxide (NO) synthase inhibitor], and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; soluble guanylyl cyclase [sGC] inhibitor). In L-NAME-treated rings, the NO-donor diethylenetriamine NONOate restored the thymoquinone-induced augmentations; 5-[1-(phenylmethyl)-1H-indazol-3-yl]-2-furanmethanol (sGC activator) and cyclic IMP (cIMP) caused similar restorations. By contrast, in ODQ-treated preparations, the cell-permeable cGMP analog did not restore the augmentation by thymoquinone. The compound augmented the content (measured with ultra-high performance liquid chromatography-tandem mass spectrometry) of cIMP, but not that of cGMP; these increases in cIMP content were prevented by endothelium removal, L-NAME, and ODQ. The augmentation of contractions caused by thymoquinone was prevented in porcine arteries, but not in rat arteries, by 1-(5-isoquinolinylsulfonyl)homopiperazine dihydrochloride and trans-4-[(1R)-1-aminoethyl]-N-4-pyridinylcyclohexanecarboxamide dihydrochloride (Rho-kinase inhibitors); in the latter, but not in the former, it was reduced by 3,5-dichloro-N-[[(1α,5α,6-exo,6α)-3-(3,3-dimethylbutyl)-3-azabicyclo[3.1.0]hex-6-yl]methyl]-benzamide hydrochloride (T-type calcium channel inhibitor), demonstrating species/vascular bed differences in the impact of cIMP on calcium handling. Thymoquinone is the first pharmacological agent that causes endothelium-dependent augmentation of contractions of isolated arteries, which requires endothelium-derived NO and biased sGC activation, resulting in the augmented production of cIMP favoring the contractile process.
authors.affiliation: Department of Pharmacology and Pharmacy and State Key Laboratory for Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong S.A.R., China (C.M.D., Z.L., S.W.S.L., A.X., P.M.V.); Department of Clinical Pharmacy, King Saud University, Saudi Arabia (K.M.A.) and Department of Physiology and Pathophysiology, Peking University Health Science Centre, Beijing, China (Z.C., Y.G.) cdetremm@hku.hk.
authors.forename: Charlotte M
authors.initials: CM
authors.lastname: Detremmerie
authors.affiliation: Department of Pharmacology and Pharmacy and State Key Laboratory for Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong S.A.R., China (C.M.D., Z.L., S.W.S.L., A.X., P.M.V.); Department of Clinical Pharmacy, King Saud University, Saudi Arabia (K.M.A.) and Department of Physiology and Pathophysiology, Peking University Health Science Centre, Beijing, China (Z.C., Y.G.).
authors.forename: Zhengju
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Pharmacology and Pharmacy and State Key Laboratory for Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong S.A.R., China (C.M.D., Z.L., S.W.S.L., A.X., P.M.V.); Department of Clinical Pharmacy, King Saud University, Saudi Arabia (K.M.A.) and Department of Physiology and Pathophysiology, Peking University Health Science Centre, Beijing, China (Z.C., Y.G.).
authors.forename: Zhuoming
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Pharmacology and Pharmacy and State Key Laboratory for Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong S.A.R., China (C.M.D., Z.L., S.W.S.L., A.X., P.M.V.); Department of Clinical Pharmacy, King Saud University, Saudi Arabia (K.M.A.) and Department of Physiology and Pathophysiology, Peking University Health Science Centre, Beijing, China (Z.C., Y.G.).
authors.forename: Khalid M
authors.initials: KM
authors.lastname: Alkharfy
authors.affiliation: Department of Pharmacology and Pharmacy and State Key Laboratory for Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong S.A.R., China (C.M.D., Z.L., S.W.S.L., A.X., P.M.V.); Department of Clinical Pharmacy, King Saud University, Saudi Arabia (K.M.A.) and Department of Physiology and Pathophysiology, Peking University Health Science Centre, Beijing, China (Z.C., Y.G.).
authors.forename: Susan W S
authors.initials: SW
authors.lastname: Leung
authors.affiliation: Department of Pharmacology and Pharmacy and State Key Laboratory for Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong S.A.R., China (C.M.D., Z.L., S.W.S.L., A.X., P.M.V.); Department of Clinical Pharmacy, King Saud University, Saudi Arabia (K.M.A.) and Department of Physiology and Pathophysiology, Peking University Health Science Centre, Beijing, China (Z.C., Y.G.).
authors.forename: Aimin
authors.initials: A
authors.lastname: Xu
authors.affiliation: Department of Pharmacology and Pharmacy and State Key Laboratory for Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong S.A.R., China (C.M.D., Z.L., S.W.S.L., A.X., P.M.V.); Department of Clinical Pharmacy, King Saud University, Saudi Arabia (K.M.A.) and Department of Physiology and Pathophysiology, Peking University Health Science Centre, Beijing, China (Z.C., Y.G.).
authors.forename: Yuansheng
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Pharmacology and Pharmacy and State Key Laboratory for Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong S.A.R., China (C.M.D., Z.L., S.W.S.L., A.X., P.M.V.); Department of Clinical Pharmacy, King Saud University, Saudi Arabia (K.M.A.) and Department of Physiology and Pathophysiology, Peking University Health Science Centre, Beijing, China (Z.C., Y.G.).
authors.forename: Paul M
authors.initials: PM
authors.lastname: Vanhoutte
mesh_terms: D000818:Animals; D001158:Arteries / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D016227:Benzoquinones / Q000737:chemistry / Q000494:pharmacology*; D007289:Cyclic IMP / Q000096:biosynthesis*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D000071756:Soluble Guanylyl Cyclase / Q000378:metabolism*; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D016227:Benzoquinones; D007289:Cyclic IMP; C004532:quinone; D000071756:Soluble Guanylyl Cyclase; C003466:thymoquinone