[Kv3.4 channel is involved in rat pulmonary vasoconstriction induced by 15-hydroxyeicosatetraenoic acid].
We have reported that hypoxia increases the activation of 15-lipoxygenase (15-LO), which converts arachidonic acid (AA) into 15-hydroxyeicosatetraenoic acid (15-HETE) in small pulmonary arteries (PAs). Through inhibition of Kv channels, 15-HETE causes more robust concentration-dependent contraction of PA rings from the hypoxic compared to the normoxic controls. However, the subtypes of Kv channels inhibited by 15-HETE are incompletely understood. The aim of the present study was to identify the contribution of Kv3.4 channel in the process of pulmonary vasoconstriction induced by 15-HETE using the tension studies of PA rings from rat with Kv3.4 channel blocker in tissue bath; to explore the role of vascular endothelium in15-HETE-induced pulmonary vasoconstriction through denuded endothelia of PA rings; and to define the downregulation of 15-HETE on the expression of Kv3.4 channel in cultured pulmonary artery smooth muscle cells (PASMCs) with RT-PCR and Western blot. In the present study, healthy Wistar rats were divided randomly into two groups: Group A with normal oxygen supply and group B with hypoxia. Six days later, the rats were killed. Pulmonary artery rings were prepared for organ bath experiments. Firstly, different concentrations of 15-HETE (10~1 000 nmol/L) were added to the Krebs solution. The isometric tension was recorded using a four-channel force-displacement transducer. Then Kv3.4 channel blocker, 100 nmol/L BDS-I, was added, followed by adding 1 mumol/L 15-HETE, and the isometric tension was recorded. Furthermore, RT-PCR and Western blot were employed to identify the influence of 15-HETE on the expression of Kv3.4 channel in cultured rat PASMCs.The results showed the PA tension was significantly increased both in groups A and B by 15-HETE in a concentration-dependent manner (P<0.05), especially in group B (P<0.05 compared to control); denuded endothelia enhanced 15-HETE concentration-related constrictions in rat PA rings; Kv3.4 channel blocker, BDS-I, significantly decreased the PA ring constriction induced by 15-HETE (P<0.05); the expressions of Kv3.4 mRNA and protein in rat PASMCs were significantly downregulated by 15-HETE (P<0.05). Based on all the information above, we conclude that Kv3.4 channel is involved in vasoconstriction induced by 15-HETE in rat PAs.
Li
Qian
Q
College of Pharmacy, Harbin Medical University, Harbin 150086, China.
Bi
Hai-Rong
HR
Zhang
Rong
R
Zhu
Da-Ling
DL
D000818:Animals; D002478:Cells, Cultured; D005260:Female; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology*; D006976:Hypertension, Pulmonary / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000473:pathology; D011651:Pulmonary Artery / Q000166:cytology / Q000503:physiopathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D051670:Shaw Potassium Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014661:Vasoconstriction / Q000187:drug effects*
D006893:Hydroxyeicosatetraenoic Acids; C492014:Kcnc4 protein, rat; D012333:RNA, Messenger; D051670:Shaw Potassium Channels; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid