title: Cellular mechanisms and intracellular signaling pathways for the modulation of eNOS in pulmonary arteries by 15-HETE.
abstract: The 15-hydroxyeicosatetraenoic acid (15-HETE), a lipid metabolite and vasoconstrictor, plays an important role in hypoxic contraction of pulmonary arteries (PAs) through working on smooth muscle cells (SMCs). Previous studies have shown that vascular endothelium is also involved in PAs tone regulation. However, little is known as to how the pulmonary artery endothelial cells (PAECs) are related to the 15-HETE-induced vasoconstriction and that which intracellular signaling systems are critical. To test this hypothesis, we examined PAs constriction in isolated rat PAs rings, the expression and activity of endothelial nitric oxide synthase (eNOS) with western blot, and nitric oxide (NO) production using the DAF-FM DA fluorescent indicator. The results showed that the 15-HETE-induced PAs constriction was diminished in endothelium-intact rings. In the presence of the eNOS inhibitor L-NAME, vasoconstrictor responses to KCl were greater than the control. The activation of eNOS was activated by Ca²⁺ released from intracellular stores and the PI3K/Akt pathway. Phosphorylations of the eNOS at Ser-1177 and Akt at Ser-473 were necessary for their activity. A prolonged 15-HETE treatment (30 min) led to a decrease in NO production by phosphorylation of eNOS at Thr-495, leading to augmentation of PAs constriction. Therefore, 15-HETE initially inhibited the PAs constriction through the endothelial NO system, and both Ca²⁺ and the PI3K/Akt signaling systems are required for the effects of 15-HETE on PAs tone regulation.
authors.affiliation: Department of Biopharmaceutical Sciences, College of Pharmacology, Harbin Medical University, Nangang District, Harbin, Heilongjiang, P. R. China.
authors.forename: Lei
authors.initials: L
authors.lastname: Yu
authors.forename: Yun
authors.initials: Y
authors.lastname: Liu
authors.forename: Zhaoping
authors.initials: Z
authors.lastname: Qiu
authors.forename: Shulin
authors.initials: S
authors.lastname: Liu
authors.forename: Xu
authors.initials: X
authors.lastname: Gao
authors.forename: Daling
authors.initials: D
authors.lastname: Zhu
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D005260:Female; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology*; D015151:Immunoblotting; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011651:Pulmonary Artery / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D006893:Hydroxyeicosatetraenoic Acids; D009569:Nitric Oxide; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt