Effect of cytokines on thrombin-stimulated increases in intracellular calcium and PGI(2) production by cultured human umbilical vein endothelial cells

The influence of cytokines on intracellular calcium concentration ([Ca2+](i)) and the production of prostacyclin (prostaglandin I-2; PGI(2)) by cultured human umbilical vein endothelial cells (HUVEC) were examined. HUVEC were incubated for 24 h in media containing interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN gamma), or interleukin-6 (IL-6), and thrombin-stimulated increases in [Ca2+](i) and PGI(2) production were then examined. Thrombin-stimulated PGI(2) production by HUVEC pretreated with 10 U/mL of IL-1 beta or 200 U/mL of TNF-alpha for 24 h was potentiated, while increases in [Ca2+](i) were suppressed. In contrast, HUVEC pretreated with 5000 U/mL of IFN-gamma for 24 h had both enhanced PGI(2) production and increases in [Ca2+](i). IL-6 affected neither PGI(2) production nor [Ca2+](i) in HUVEC stimulated with thrombin. The burst increase in thrombin-stimulated PGI(2) production by HUVEC pretreated with cytokines did not correlate with the increase in [Ca2+](i). Cytokines have been reported to induce enzymes involved in the arachidonic acid cascade, such as phospholipase A(2) (PLA(2)) and cyclooxygenase-2 (COX-2). Therefore, the increase in [Ca2+](i) does not appear to be as important for thrombin-stimulated PGI(2) production as does the induction of these enzymes by cytokines.