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Microparticles in endothelial cell and vascular homeostasis: are they really noxious?

Haematologica (Impact Factor: 5.87). 04/2009; 94(3):313-7. DOI: 10.3324/haematol.2009.003657
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    ABSTRACT: Circulating microparticles (MPs) have been reported to be associated with coronary artery disease (CAD). In this study, we explored the relationship between MPs procoagulant activity and characteristics of atherosclerotic plaque detected by 64-slice computed tomography angiography (CTA). In 127 consecutive patients with CAD but without acute coronary syndrome and who underwent 64-slice CTA, MPs procoagulant activity in plasma (by a thrombin generation test), soluble form of lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) and N(epsilon)-(carboxymethyl) lysine (CML) circulating levels (by ELISA) were measured. A quantitative volumetric analysis of the lumen and plaque burden of the vessel wall (soft and calcific components), for the three major coronary vessels, was performed. The patients were classified in three groups according to the presence of calcium volume: non-calcified plaque (NCP) group (calcium volume (%) = 0), moderate calcified plaque (MCP) group (0 < calcium volume (%) < 1), and calcified plaque (CP) group (calcium volume (%) ≥ 1). MPs procoagulant activity and CML levels were higher in MCP group than in CP or NCP group (P = 0.009 and P = 0.027, respectively). MPs procoagulant activity was positively associated with CML (r = 0.317, P < 0.0001) and sLOX-1 levels (r = 0.216, P = 0.0025). MPs procoagulant activity was higher in the MCP patient group and correlated positively with sLOX-1 and CML levels, suggesting that it may characterize a state of blood vulnerability that may locally precipitate plaque instability and increase the risk of subsequent major cardiovascular events.
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    ABSTRACT: An acute bout of exercise can improve endothelial function and insulin sensitivity when measured on the day following exercise. Our aim was to compare acute high-intensity continuous exercise (HICE) to high-intensity interval exercise (HIIE) on circulating endothelial microparticles (EMPs) and insulin sensitivity in overweight/obese men and women. Inactive males (BMI = 30 ± 3, 25 ± 6 yr, n = 6) and females (BMI = 28 ± 2, 21 ± 3 yr, n = 7) participated in three experimental trials in a randomized counterbalanced crossover design: 1) No exercise control (Control); 2) HICE (20 min cycling @ just above ventilatory threshold); 3) HIIE (10 X 1-min @ ∼90% peak aerobic power). Exercise conditions were matched for external work and diet was controlled post-exercise. Fasting blood samples were obtained ∼18 hr after each condition. CD62E+ and CD31+/CD42b- EMPs were assessed by flow cytometry and insulin resistance (IR) was estimated by homeostasis model assessment (HOMA-IR). There was a significant sex X exercise interaction for CD62E+ EMPs, CD31+/CD42b- EMPs, and HOMA-IR (all P<0.05). In males, both HICE and HIIE reduced EMPs compared to Control (P≤0.05). In females, HICE increased CD62E+ EMPs (P<0.05 vs. Control) whereas CD31+/CD42b- EMPs were unaltered by either exercise type. There was a significant increase in HOMA-IR in males but a decrease in females following HIIE compared to Control (P<0.05). Overweight/obese males and females appear to respond differently to acute bouts of high-intensity exercise. A single session of HICE and HIIE reduced circulating EMPs measured on the morning following exercise in males but in females CD62E+ EMPs were increased following HICE. Next day HOMA-IR paradoxically increased in males but was reduced in females following HIIE. Future research is needed to investigate mechanisms responsible for potential differential responses between males and females.
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