Signal induction and molecular mechanisms of the thrombin induced prostaglandin I
2 (PGI
2) synthesis in human umbilical vein endothelial cells (HUVEC) were investigated in association with the intra Ca
2+ and the gene expression of prostaglandin H
2 synthase (PGHS) and phospholipase A
2 (PLA
2) using the method of competitive polymerase chain reaction (PCR). Thrombin enhanced the synthesis of PGI
2 by time dependent manner. Thrombin stimulation caused an elevation of the cytosolic Ca
2+, which in turn stimulate phospholipase A
2 (PLA
2), resulting in arachidonic acid cleavage from membrane phospholipids and its subsequent conversion into PGI
2 through PGHS pathway. The elevated cytosolic Ca
2+ resulted from mainly the influx of extracellular Ca
2+. Compatible to former reports, PGHS-1 mRNA was constitutively expressed, while PGHS-2 and PLA
2 mRNA was not. With the stimulation of thrombin, PLA
2 mRNA increased to 9-fold in 15 minutes, PGHS-1 mRNA to 3.4-fold in 180 minutes, PGHS-2 mRNA to 38-fold in 60 minutes. These results suggest that PGHS-1 is not only the constitutive enzyme but also the inducible enzyme and expression of PLA
2, PGHS-1, PGHS-2 mRNA cause to PGI
2 generation.
抄録全体を表示