Abstract
Leukocyte-vascular endothelial cell (EC) interactions which promote inflammatory and immune reactions involve bidirectional signaling between the two cell types. We investigated the effects of flow on neutrophil-mediated changes in endothelial intracellular Ca2+ levels ( [Ca2+] i) . Cultured human umbilical vein ECs stimulated with endotoxin were labeled with Fura-2 and exposed to fluid flow with neutrophils. Individual changes in [Ca2+] iwere monitored. Application of flow with neutrophils to stimulated ECs led to an increase in [Ca2+] i although neither flow without neutrophils nor neutrophils without flow rarely induced rises in [Ca2+] i. Furthermore, flow application with neutrophils to unstimulated ECs also rarely promoted rises in [Ca2+] i. These findings suggest that flow may contribute to initiation or enhancement of the inflammatory process via induction of Ca2+ signaling in endotoxin-stimulated endothelium facing neutrophils in blood flow.
