The proposed research aims to provide training experiences for a promising postdoctoral fellow to become an independent scientist in a health-related field through collaborative efforts between the trainee and sponsor. To gain a better understanding of disease associated microvascular dysfunction, we have recently used the streptozotocin-induced diabetic rat model to examine hyperglycemia-induced changes in microvessel permeability. Although diabetes-associated vascular complications have been studied extensively, quantitative measurements of microvessel permeability in diabetic animals have not yet been done and the factors that contribute to the microvascular dysfunction under diabetic conditions remain unclear. Our permeability measurements in diabetic rat microvessels showed significantly increased baseline permeability and a markedly augmented permeability response to inflammatory mediators. In the plasma of these diabetic rats, we found significantly increased levels of circulating microparticles (MPs) when compared to normal rats. Following the perfusion of MPs isolated from diabetic rat plasma into intact microvessels, we observed increases in leukocyte adhesion on the microvessel walls as well as thrombus formation. Based on the novel preliminary findings we hypothesize that the increased MPs under diabetic conditions are not simply the result of vascular dysfunction, but that MPs actively mediate pro-inflammatory and pro-coagulant signaling and thus potentiate vascular dysfunction under diabetic disease conditions. This hypothesis will be tested by three specific aims. Aim 1 is to identify sources of the increased MPs in diabetic rats and investigate the mechanisms by which MP levels increase under diabetic conditions. Aim 2 is to investigate mechanisms by which MPs interact with microvessel walls, mediating leukocyte adhesion and increases in microvascular permeability. Aim 3 is to investigate the effect of MPs on promoting the coagulation that results in thrombus formation in intact microvessels. The innovative aspect of this proposal is that we will combine flow cytometry analysis of MPs with confocal imaging and quantitative measurement of permeability in individually perfused intact microvessels. This proposed study will provide the most direct in vivo evidence for the effects of microparticles on the development of vascular complications and contribute to a better understanding of the pathogenesis of vascular dysfunction associated with diabetes. The results and knowledge gained from this study will benefit the development of therapeutic and preventive strategies for diabetic vascular dysfunctions. The completion of these proposed studies will broaden the applicant's scientific perspective and experimental methodologies while enhancing the applicant's potential to become an independent researcher in the field of biomedical sciences.