title: Tanshinone IIA modulates pulmonary vascular response to agonist and hypoxia primarily via inhibiting Ca2+ influx and release in normal and hypoxic pulmonary hypertension rats.
abstract: The present study was designed to investigate the vascular effects and underlying mechanisms of tanshinone IIA on isolated rat pulmonary artery. Isometric tension was recorded in the arteries from normal and hypoxic pulmonary hypertension rats under normoxia or hypoxia condition. The results showed that tanshinone IIA exerted a biphasic effect on rat pulmonary artery. The constriction was attenuated by endothelium-denudation but was enhanced by inhibition of nitric oxide synthase. Pretreatment with tetraethylammonium (Ca2+-activated K+ channel inhibitor) upward shifted the concentration-response curve without affecting the maximum dilatation. Pretreatment with zinc protoporphyrin IX (heme oxygenase-1 inhibitor), 4-aminopyridine (KV channel inhibitor), glibenclamide (KATP channel inhibitor) or BaCl2 (inwardly rectifying K+ channel inhibitor) did not affect the vasoreactivity. Meanwhile, tanshinone IIA almost abolished vasoconstriction induced by extracellular Ca2+. Under hypoxia condition, tanshinone IIA eliminated acute hypoxia-induced initial contraction, potentiated following vasorelaxation, attenuated and reversed sustained contraction to relaxation in pulmonary artery from normal rats, and reversed phenylephrine-induced sustained constriction to sustained relaxation in remodeled pulmonary artery from hypoxic pulmonary hypertension rats. We concluded that the mild constrictive effect induced by tanshinone IIA was affected by integrity of endothelium and production of nitric oxide, while the potent dilative effect was endothelium-independent and produced primarily by inhibiting extracellular Ca2+ influx and partially by inhibiting intracellular Ca2+ release, as well as activating Ca2+-activated K+ channels. The modulation of tanshinone IIA on pulmonary vasoreactivity under both acute and chronic hypoxia condition may provide a new insight for curing hypoxic pulmonary hypertension.
authors.affiliation: Department of Pathology and Pathophysiology, Fourth Military Medical University, Xi'an, 710032, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Ming-Qing
authors.initials: MQ
authors.lastname: Dong
authors.forename: Man-Ling
authors.initials: ML
authors.lastname: Liu
authors.forename: Dun-Quan
authors.initials: DQ
authors.lastname: Xu
authors.forename: Ying
authors.initials: Y
authors.lastname: Luo
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Liu
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.forename: Peng-Tao
authors.initials: PT
authors.lastname: Zhao
authors.forename: Yu-Qi
authors.initials: YQ
authors.lastname: Gao
authors.forename: Zhi-Chao
authors.initials: ZC
authors.lastname: Li
mesh_terms: D045784:Abietanes; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002248:Carbon Monoxide / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D006976:Hypertension, Pulmonary / Q000150:complications / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D000860:Hypoxia / Q000150:complications*; D066298:In Vitro Techniques; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D010616:Phenanthrenes / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011453:Prostaglandins / Q000378:metabolism; D011651:Pulmonary Artery / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects
chemical_list: D045784:Abietanes; D010616:Phenanthrenes; D026902:Potassium Channel Blockers; D011453:Prostaglandins; C021751:tanshinone; D010656:Phenylephrine; D009569:Nitric Oxide; D002248:Carbon Monoxide; D011188:Potassium; D002118:Calcium