Bottaro, Donald Paul2023-08-222023-08-221986https://hdl.handle.net/2144/46579Investigations were conducted to characterize endothelial cell (EC) movement and barrier function in vitro and to investigate their potential interrelationship. Specifically, the mediation of EC movement and barrier function by vasoactive amines, and the relevance of this mediation to a potential mechanism by which blood platelets may help maintain microvascular integrity, was examined. The effects of the platelet constituents serotonin (5-HT) and norepinephrine (NE) and the effects of histamine on bovine aortic endothelial cell (BAEC) and vascular smooth muscle cell (VSMC) movement were quantitated using a phagokinetic tracking assay. BAEC movement was significantly reduced by 5-HT, NE, and histamine, while VSMC motility was significantly enhanced by 5-HT and histamine, but reduced by NE. The use of specific receptor antagonists revealed that the 5-HT- and NE-associated inhibition of BAEC movement may be mediated by beta-adrenergic receptors, and the histamine-associated inhibition may be partially mediated by H-1 receptors. An assay to measure the passage of a trypan blue dye-bovine serum albumin conjugate (TB-BSA) across cells grown on microcarriers was used to compare the barriers provided by EC and other cell types. VSMC or 3T3 fibroblasts impeded TB-BSA diffusion significantly less than BAEC, suggesting that barrier formation may be an EC-specific phenomenon. Treatment of BAEC with 5-HT or NE significantly impeded TB-BSA diffusion relative to untreated controls. In contrast, histamine treatment significantly increased TB-BSA diffusion. The amine-associated effects were dose-dependent and cell-specific, and in some cases appeared to be receptor-mediated. BAEC and pulmonary microvessel EC (PMEC) barriers were quantitatively comparable, but significantly more permeable than that observed for cerebral microvessel EC (CMEC). Glutaraldehyde fixation and low temperature reduced TB-BSA passage across BAEC by <30%, indicating that the bulk of tracer movement occurred via intercellular diffusion. Treatment with cytochalasin resulted in significant BAEC and CMEC barrier loss, suggesting that microfilament bundles are involved EC junctional maintenance. Collectively, the results suggest a dynamic model of vascular permeability in which intercellular macromolecular diffusion may be regulated by EC junctional apposition, and responsive to physiologic -agents that affect EC movement.en-USThis work is being made available in OpenBU by permission of its author, and is available for research purposes only. All rights are reserved to the author.BiologyCytologyCytology, researchThesis/Dissertation