ESTROGENS MODULATE BOVINE VASCULAR ENDOTHELIAL-CELL PERMEABILITY AND HSP-25 EXPRESSION CONCOMITANTLY

The atheroprotective properties of estrogens are supported by clinical data from postmenopausal women who use estrogen replacement therapy H owever, the mechanisms mediating activity remain unknown, and it has b een suggested that estrogens may help to modulate endothelial permeabi lity to atherogenic lipoproteins. In these studies we used bovine vasc ular endothelial cells as an in vitro model to show that estrogens wer e able to regulate low-density Lipoprotein transport and permeability of the endothelial monolayer. Macromolecular transport was observed to be a second-order polynomial function of estrogen concentration Moreo ver, this regulation was correlated with expression of heat shock prot ein (HSP) 25, which is known to influence fluid phase pinocytosis and cytoskeleton remodeling, thus suggesting a role for HSP 25 in the estr ogenic control of transcellular permeability of the endothelium monola yer.