The molecular pathway of ATP-sensitive potassium channel in endothelial cells for mediating arteriole relaxation.

AIMS: The endothelial molecular pathway of a new ATP-sensitive potassium channel (KATP) opener natakalim was investigated in mesenteric arterioles of rats.

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METHODS

A DMT wire myograph was used to evaluate the vasorelaxation effects of natakalim. Ca(2+) responses of endothelial cells induced by natakalim were measured by laser confocal fluorescence microscopy. NO assay kits and Western blotting were used.

KEY FINDINGS: The new KATP opener natakalim significantly produced endothelium-dependent arteriolar dilation and increased endothelial cell intracellular calcium concentration ([Ca(2+)]i) as well as NO release, which could be inhibited by SB366791 and capsazepine, the specific TRPV1 blockers. Additionally, down-regulation of endothelial TRPV1 by RNA interference inhibited the Ca(2+) influx induced by natakalim.

SIGNIFICANCE: These results suggest that endothelial KATP mediated natakalim-induced vasorelaxation through increasing [Ca(2+)]i and NO production. Activation of endothelial TRPV1 channels and subsequent Ca(2+) entry, and NO release at least partly contribute to endothelium-dependent vasorelaxation induced by natakalim.