Abstract 1170: Novel Pathway of the Endothelin-1 and Reactive Oxygen Species in Coronary Vasospasm with Endothelial Dysfunction
The role of endothelial dysfunction in the mechanism of coronary vasospasm is controversial. We hypothesized that reactive oxygen species (ROS) and endothelin (ET)-1 are plausible candidate as a mediator of vasospasm linked to endothelial dysfunction. We tested this hypothesis by using pig model in which balloon endothelial denudation (ED) of the left anterior descending coronary artery (LAD) was carried out every 2 weeks (W). Intracoronary administration of serotonin (n = 12) induced ED site narrowing from 7.3 ± 1.2% (0W, before injury) to 94.2 ± 6.8% (8W, 2W after 4 times ED, p < .01) with myocardial ischemia. At the end of the experiment at 8W, we performed in vitro study using isolated LAD samples. ET converting enzyme (ECE) and ET-1 histofluorescences in ED site were upregulated (ECE 2.4 ± 0.6 fold, ET-1 5.8 ± 0.8 fold vs. non-ED site, p < .01, respectively). Protein densities of eNOS in ED site decreased in the Western blotting (0.24 ± 0.05 fold vs. non-ED site, p < .01). P47phox, ROS and ET-1 histofluorescence intensities increased with serotonin stimulation in ED site (p47phox 5.2 ± 0.4 fold in intima , ROS 14.3 ± 1.4 fold in intima, ET-1 14.4 ± 1.5 fold in media, vs. before serotonin, p < .01, respectively), which decreased with preexposure of NADPH oxidase inhibitor apocynin (p < .01). Phosphorylation of myosin light chain (pMLC) in Western blotting was appeared with serotonin stimulation in ED site (6.09 ± 0.55 fold vs. before serotonin, p < .01). Calmodulin inihibitor W-7 eliminated pMLC with serotonin (0.88 ± 0.12 fold), though inhibition of pMLC by Rho-kinase inhibitor hydroxyfasudil was small. Chronic oral administration of ETA receptor antagonist TA0201 (n = 12) for 8W, eliminated not only serotonin induced ED site narrowing (8W: 19.3 ± 4.9%) but also upregulations of p47phox , ROS and ET-1 fluorescence intensities with serotonin stimulation in ED site (p47phox 0.92 ± 0.1 fold, ROS 1.02 ± 0.2 fold, ET-1 0.98 ± 0.1 fold vs. before serotonin, p < .01, respectively). Likewise, pMLC with serotonin was completely eliminated. Thus, under the coronary artery endothelial dysfunction, ET-1 is essential for ROS-dependent coronary vasospasm through CaM pathway. These results suggest a mechanistic link between endothelial dysfunction and coronary spasm.