Thrombin-Stimulated Endothelial Cell Functions: Monocyte Adhesion and PDGF Production
In the past decade there has been much interest in the concept of an activated or injured endothelium that exhibits properties distinct from healthy, adult endothelium. The activated state of the endothelial cell may result from the action of cytokines, as recently reviewed in detail by Pober and Cotranl. Alternatively, injury to the endothelium may shorten endothelial cell lifetime, causing increased turnover in specific regions of the artery. This may, in turn, lead to the expression of genes which are suppressed under physiological rather than pathological conditions, even in the absence of exogenous stimulators. Extrapolation of in vitro findings has suggested to us a possible role of dysfunctional endothelium in the development of the atherosclerotic plaque2. Activated endothelial cells may (1) express binding sites for monocytes and perhaps secrete monocyte activators; (2) secrete oxygen free radicals that can modify nearby low density lipoprotein (LDL); (3) act as a procoagulant rather than an anticoagulant surface, and (4) synthesize and secrete a PDGF-like protein and/or other mitogens and chemoattractants for medial smooth muscle cells.
KeywordsHistamine Thrombin Inositol Pertussis Bradykinin
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