Microparticles from Patients Undergoing Percutaneous Coronary Intervention Impair Vasodilatation by Uncoupling Endothelial Nitric Oxide Synthase

OBJECTIVES: Percutaneous coronary interventions (PCIs) save countless acute myocardial infarction (AMI) patients. However, endothelial injury is still an inevitable complication. Circulating microparticles (MPs) play important roles in vascular dysfunction. Whether PCI affects function of MPs remains unclear. METHODS: MPs were obtained from AMI patients (n = 38) both preoperatively and 24 h after PCI, and healthy subjects (n = 20). MPs origins were tested by flow cytometry. Rat thoracic aortas were incubated with MPs to determine the effects of MPs on phosphorylation of endothelial nitric oxide synthase (eNOS), caveolin-1 expression, eNOS association with heat shock protein 90 (Hsp90), generation of nitric oxide (NO) and superoxide anion (O2), and endothelial-dependent vasodilatation. RESULTS: Compared with healthy subjects, MP concentrations increased in AMI patients. Undergoing PCI had no further effect on MPs concentration, but it results in increased endothelial-derived MPs proportion and decreased platelet-derived MP ratio. MPs from AMI patients decreased eNOS phosphorylation at Ser1177, increased eNOS phosphorylation at T495 and caveolin-1 expression, decreased eNOS association with Hsp90, decreased NO production but increased (O2) generation, damaged endothelial-dependent vasodilatation. All of these effects of MPs were strengthened by PCI. CONCLUSIONS: PCI further enhances the vascular injury effect of MPs. Circulating MPs may be a potential therapeutic target for patients undergoing PCI.