Ouabain at pathological concentrations might induce damage in human vascular endothelial cells.
OBJECTIVE
To examine the time- and dose-dependent effects of ouabain on human umbilical vein endothelial cells (HUVEC) in vivo, and the changes in aortic endothelium and the different expression levels of Kv4.2 in vitro.


METHODS
The proliferation of HUVEC and cell death were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, the incorporation of [3H]TdR, trypan blue staining, and lactate dehydrogenase (LDH) release. The response of endothelial cells to ouabain was explored with a complementary DNA microarray and a candidate gene was found. Ouabain-sensitive hypertensive rats were established by chronic administration of ouabain. Changes in the aortic endothelium were observed by electron microscopy, and the expression level of Kv4.2 in different animals was studied by using real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR).


RESULTS
Ouabain stimulated the proliferation of HUVEC at physiological concentrations (0.3-0.9 nmol/L). Ouabain at pathological concentrations (0.9-1.8 nmol/L) inhibited proliferation and induced cell death. mRNA profile analysis indicated that 340 genes were differentially expressed after ouabain treatment: 145 were upregulated, of which 6 were upregulated significantly, including KCND2 (encoding the potassium voltage-gated channel shal-related subfamily member 2). The upregulated genes were mainly related to cell metabolism and transcription. In ouabain-sensitive hypertensive rats, the aortic endothelium was damaged and Kv4.2 (coded by KCND2) was over-expressed.


CONCLUSIONS
The physiological role of ouabain in HUVEC might involve the control of growth and metabolism. Ouabain at pathological concentrations might affect the structure and function of the vascular endothelium by modification of expression of the KCND2 gene, and participate vascular remodeling in hypertension.
Ren
Yan-ping
YP
Geriatric-Cardiovascular Department, First Hospital of Xi-an Jiaotong University, Xi-an 710061, China. ryp0071@126.com
Huang
Ruo-wen
RW
Lü
Zhuo-ren
ZR
D001011:Aorta / Q000473:pathology; D016923:Cell Death / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000166:cytology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D006973:Hypertension / Q000473:pathology* / Q000503:physiopathology; D010042:Ouabain / Q000008:administration & dosage / Q000494:pharmacology*; D051672:Shal Potassium Channels / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology
D051672:Shal Potassium Channels; D010042:Ouabain