The mechanisms for the transendothelial transport of macromolecules are poorly understood. Much of this lack of understanding is due to the complexity of studying transendothelial transport in situ. We have developed an in vitro model of the endothelium which facilitates precise control and monitoring of the forces on both sides of the endothelium. The model consists of monolayers of endothelial cells cultured on a subsrate impregnated micropore filter. Tight junctions develop between the endothelial cells, the endothelial monolayer develops an electrical resistance comparable to in situ endothelia, and the albumin permeability of the monolayers is also similar to in situ endothelia. Using this model, we have recently observed that the endothelium actively transports albumin from interstitium to lumen. The interstitial-to-luminal flux is favored over the luminal-to-interstitial flux by a factor of 10-40 depending on interstitial albumin concentration. The positive interstitial-to-luminal flux ratio is preserved against a concentration gradient and is abolished by depleting endothelial cell energy stores. In more recent experiments, we have found that ouabain inhibits this active interstitial-to-luminal albumin transport. The proposed studies are designed to more completely characterize this active transport process in terms of its kinetics, its energy dependence, its coupling to Na-K-ATPase activity and its ability to be regulated by messenger molecules. The active transport of albumin may be important to the normal function of the endothelium in controlling the egress of water and solutes from the vascular space. It may also be important in controlling the entrance of macromolecules into the vessel wall and hence in the pathogenesis of atherosclerosis.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL036605-04
Application #
3351696
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Project Start
1986-07-01
Project End
1991-06-30
Budget Start
1989-07-01
Budget End
1990-06-30
Support Year
4
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of Iowa
Department
Type
Schools of Medicine
DUNS #
041294109
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Winter, M C; Peterson, M W; Shasby, D M (1991) Synergistic effects of a calcium ionophore and activators of protein kinase C on epithelial paracellular permeability. Am J Respir Cell Mol Biol 4:470-7
Wilson, J; Winter, M; Shasby, D M (1990) Oxidants, ATP depletion, and endothelial permeability to macromolecules. Blood 76:2578-82
Winter, M; Wilson, J S; Bedell, K et al. (1990) The conductance of cultured epithelial cell monolayers: oxidants, adenosine triphosphate, and phorbol dibutyrate. Am J Respir Cell Mol Biol 2:355-63
Shasby, D M; Hampson, F (1989) Effects of chlorinated amines on endothelial and epithelial barriers in vitro and ex vivo. Exp Lung Res 15:345-57
Carson, M R; Shasby, S S; Shasby, D M (1989) Histamine and inositol phosphate accumulation in endothelium: cAMP and a G protein. Am J Physiol 257:L259-64
Shasby, D M; Yorek, M; Shasby, S S (1988) Exogenous oxidants initiate hydrolysis of endothelial cell inositol phospholipids. Blood 72:491-9
Shasby, D M; Winter, M; Shasby, S S (1988) Oxidants and conductance of cultured epithelial cell monolayers: inositol phospholipid hydrolysis. Am J Physiol 255:C781-8
Shasby, D M; Stoll, L L; Spector, A A (1987) Polarity of arachidonic acid metabolism by bovine aortic endothelial cell monolayers. Am J Physiol 253:H1177-83
Shasby, D M; Peterson, M W (1987) Effects of albumin concentration on endothelial albumin transport in vitro. Am J Physiol 253:H654-61
Peterson, M W; Stone, P; Shasby, D M (1987) Cationic neutrophil proteins increase transendothelial albumin movement. J Appl Physiol 62:1521-30

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