Abstract 19796: Vascular eNOS S-Glutathionylation is Increased in Hypertension and Atherosclerosis with eNOS uncoupling: Data from Animal Models and Human Aortic Tissue of Patients Undergoing Surgical Revascularization

Abstract

Background: In vascular diseases, including hypertension (HTN) and atherosclerosis, endothelial dysfunction (ED) occurs secondary to altered function of endothelial NO synthase (eNOS); however, questions remain regarding the mechanism by which this occurs and how it can be reversed. We recently identified a novel redox regulated pathway through which eNOS is uncoupled due to S-glutathionylation. In vessels from spontaneous hypertensive rats (SHR) and in aortic tissue from patients undergoing coronary bypass (CABG) surgery, we measure eNOS S-glutathionylation and its effect on eNOS coupling. Methods: Studies were performed in aortic, femoral and carotid vessels from adult SHR rats and in aortic tissue from patients undergoing CABG or other vascular surgery. S-glutathionylation of eNOS was studied using anti-glutathione antibody, anti-eNOS antibody and an antibody specific for eNOS C689 S-glutathionylation. NO and superoxide (•O2--) was measured using fluorescent probes CuFL and DHE, respectively, in the absence or presence of the NOS inhibitor, L-NAME, NO scavenger, PTIO, or the SOD mimetic, MnTBAP. Results & Conclusion: Immunohistology and immunoblotting revealed increased eNOS S-glutathionylation in vessels of SHR rats compared to matched WKY controls. The reducing agent DTT reversed this glutathionylation and reversed the impairment in endothelial-dependent relaxation measured from aortic rings. Mass spectroscopy on immunoprecipitated eNOS demonstrated modification at C689 in aorta of SHR but not WKY rats. Immunohistology with a specific eNOS C689 S-glutathionylation antibody confirmed endothelial C689 S-glutathionylation. Decreased NO and increased •O2-- was seen in these vessels. In patients undergoing CABG, high levels of C689 S-glutathionylation was seen abolished by DTT. Thus, eNOS S-glutathionylation is increased in an animal model of HTN with resultant ED and present in patients with coronary disease undergoing bypass surgery.