Investigations 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.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/46579 |
| Date | January 1986 |
| Creators | Bottaro, Donald Paul |
| Publisher | Boston University |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Rights | This 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. |
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