RESUMO
AIM:To investigate the mechanism of endothelium-derived microparticles(EMP)-induced endothelial dysfunction and the role of superoxide anion(O-?2) in EMP-induced endothelial dysfunction.METHODS:EMP were isolated from human umbilical vein endothelial cells stimulated with plasminogen activated inhibitor-1.(1) Cultured bovine aortic endothelial cells(BAEC) were divided into 3 groups and pretreated with nothing in group 1,EMP(1?108/L) in group 2,EMP(1?108/L) + L-nitroarginiemethylester(L-NAME,1 mmol/L) in group 3 for 30 min and A23187(5 ?mol/L) stimulated O-?2 generation was determined by superoxide dismutase(SOD)-inhibitable ferricytochrome C reduction.(2) Facialis arteries(60-150 microns) were isolated from C57BL/6 mice and divided into 4 groups.The vessels were pretreated with nothing in group 1,EMP(1?108/L) in group 2,EMP(1?108/L) + SOD(2?105 U/L) in group 3,EMP(1?108/L) + polyethylene glycolated-SOD(PEG-SOD,2?105 U/L) in group 4 for 10 min and acetylcholine(ACH)-induced vasodilation was measured.RESULTS:(1) EMP significantly increased O-?2 generation in BAEC culture,which was prevented about 50% by pretreating the BAEC with L-NAME.(2) EMP significantly impaired ACH-induced vasodilation.SOD could not restore EMP-impaired ACH-induced vasodilation and PEG-SOD showed partial restoration of vasodilation.CONCLUSION:These data indicate that at least some EMP-induced endothelial dysfunction occurs by inducing intracellular O-?2 generation.It may provide a theoretical evidences in finding a multiple treatment including removal of O-?2 in the future.