Copyright © 2006, European Society of Cardiology
A new ATP-sensitive potassium channel opener protects endothelial function in cultured aortic endothelial cells
aDepartment of Cardiovascular Pharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
bThadweik Academy of Medicine, Beijing, China
cEnhua Academy of Medicine, Beijing, China
* Corresponding author. Tel.: +86 10 6693 2651; fax: +86 10 6816 8180. Email address: wh9588{at}yahoo.com.cn
Objective: Endothelial dysfunction is an early risk factor for cardiovascular disease and hypertension. Mechanisms that participate in endothelial dysfunction include reduced nitric oxide (NO) generation and increased endothelin-1 (ET-1) generation. Endothelial ATP-sensitive potassium (KATP) channels are responsible for maintaining the resting potential of endothelial cells and modulating the release of vasoactive compounds. We hypothesized that activation of endothelial KATP channels might result in the protection against endothelial dysfunction. Methods: Using cultured bovine or rat aortic endothelial cells, we examined the effects of a new KATP channels opener, iptakalim, on the secretion of vasoactive substances. We also investigated its effects on the expression of adhesion molecules in metabolically disturbed cultured endothelial cells. Results: In cultured aortic endothelial cells, iptakalim caused a concentration-dependent inhibition of ET-1 release and synthesis that correlated with reduced levels of mRNA for ET-1 and endothelin-converting enzyme. These effects of iptakalim were significantly inhibited by pretreatment with glibenclamide (a KATP channel blocker) for 1 h. Similarly, iptakalim enhanced the release of NO in a concentration-dependent manner and increased basal levels of free intracellular calcium. Iptakalim at the concentrations of 100 and 1000 µM increased the activities of NO synthase (NOS) significantly. After the activity of NOS was blocked by L-N
-nitro-arginine methyl ester (L-NAME), the inhibition of iptakalim on ET-1 release was abolished. In endothelial cell models of metabolic disturbance induced by low-density lipoprotein, homocysteine, or hyperglycemia, treatment with iptakalim could inhibit the overexpression of monocyte chemoattractant protein-1 (MCP-1), Intercellular adhesive molecule-1 (ICAM-1), and vascular cell adhesive molecule-1 (VCAM-1) mRNA. Conclusion: Iptakalim is a promising drug that could protect against endothelial dysfunction through activating KATP channels in endothelial cells.
KEYWORDS ATP-sensitive potassium channel opener; Iptakalim; Endothelial function; Endothelium
Time for primary review 9 days
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