Subacute hypoxia suppresses Kv3.4 channel expression and whole-cell K+ currents through endogenous 15-hydroxyeicosatetraenoic acid in pulmonary arterial smooth muscle cells.
We have previously reported that subacute hypoxia activates lung 15-lipoxygenase (15-LOX), which catalyzes arachidonic acid to produce 15-HETE, leading to constriction of neonatal rabbit pulmonary arteries. Subacute hypoxia suppresses Kv3.4 channel expression and results in an inhibition of whole-cell K(+) currents (I(K)). Although the Kv channel inhibition is likely to be mediated through 15-HETE, direct evidence is still lacking. To reveal the role of the 15-LOX/15-HETE pathway in the hypoxia-induced down-regulation of Kv3.4 channel expression and inhibition of I(K), we performed studies using 15-LOX blockers, whole-cell patch-clamp, semi-quantitative PCR, ELISA and Western blot analysis. We found that Kv3.4 channel expression at the mRNA and protein levels was greatly up-regulated in pulmonary arterial smooth muscle cells after blockade of 15-LOX by CDC or NDGA. The 15-LOX blockade also partially restored I(K). In comparison, 15-HETE had a stronger effect than 12-HETE on the expression of Kv3.4 channels. 5-HETE had no noticeable effect on Kv3.4 channel expression. These data indicate that the 15-LOX pathway via its metabolite, 15-HETE, seems to play a role in the down-regulation of Kv3.4 expression and I(K) inhibition after subacute hypoxia.
Guo
Lei
L
Department of Biopharmaceutical Sciences, College of Pharmacy, Harbin Medical University, Harbin 150081, China.
Tang
Xiaobo
X
Tian
Hua
H
Liu
Ye
Y
Wang
Zhigang
Z
Wu
Hong
H
Wang
Jing
J
Guo
Sholi
S
Zhu
Daling
D
D000818:Animals; D001093:Arachidonate 15-Lipoxygenase / Q000378:metabolism; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002469:Cell Separation; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism / Q000502:physiology*; D000860:Hypoxia / Q000378:metabolism*; D007202:Indicators and Reagents; D032389:Myocytes, Smooth Muscle / Q000378:metabolism / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011651:Pulmonary Artery / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051670:Shaw Potassium Channels / Q000096:biosynthesis* / Q000235:genetics
D006893:Hydroxyeicosatetraenoic Acids; D007202:Indicators and Reagents; C492014:Kcnc4 protein, rat; D012333:RNA, Messenger; D051670:Shaw Potassium Channels; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D001093:Arachidonate 15-Lipoxygenase; D002118:Calcium