Effects of Bradykinin on Prostaglandin I ₂ Synthesis in Human Vascular Endothelial Cells

Abstract

The effects of bradykinin on the regulatory mechanisms of prostacyclin synthesis in endothelial cells were investigated in association with intracellular Ca(2+) kinetics, cytosolic phospholipase A(2) (cPLA(2)) activity, and mRNA expression of cPLA(2) and prostaglandin H synthase (PGHS) isoforms. Bradykinin enhanced prostacyclin release from endothelial cells time-dependently, but pretreatment with EGTA H-7 or HOE 140 inhibited bradykinin-induced prostacyclin release. Bradykinin increased both the influx of extracellular Ca(2+) and Ca(2+) release from the intracellular Ca(2+) storage sites. These reactions occurred within 5 minutes after bradykinin stimulation. Within 15 minutes, bradykinin activated cPLA(2) to 1.3-fold the control level. The constitutive expressions of mRNA of cPLA(2), PGHS-1, and PGHS-2 was 87, 562, and 47 amol/microg RNA, respectively. With the stimulation of bradykinin, cPLA(2) mRNA increased to 746 amol/microg RNA in 15 minutes, PGHS-1 mRNA increased to 10 608 amol/microg RNA, and PGHS-2 mRNA increased to 22 400 amol/microg RNA in 180 minutes. Pretreatment with cycloheximide superinduced cPLA(2) and PGHS-2 mRNA expression but almost completely inhibited PGHS-1. Pretreatment with EGTA had effects similar to pretreatment with cycloheximide in the case of cPLA(2) and PGHS-1 but did not affect PGHS-2. These findings suggest that the elevation of cPLA(2) activity caused by the increase of intracellular Ca(2+) concentration is important in the early phase of bradykinin-induced prostacyclin synthesis and that the mechanisms regulating cPLA(2) are different from those regulating PGHS isoforms in endothelial cells.

Calcium dobesilate potentiates endothelium‐derived hyperpolarizing factor‐mediated relaxation of human penile resistance arteries

“…NO is a key mediator of endothelium‐dependent relaxation (Moncada et al ., 1987), but it is not the only relaxant factor derived from the endothelium. It is well known that, in response to various stimuli, the human endothelium is able to produce prostacyclin (Osanai et al ., 2000; Yamasaki et al ., 2000), which, in turn, has the ability to relax a large number of vascular beds, including penile arteries (Angulo et al ., 2002). Furthermore, the endothelium‐dependent relaxation of some human resistance arteries has a component resistant to the inhibition of NO and prostacyclin production, which is attributed to EDHF (Miura et al ., 1999; Coats et al ., 2001).…”

Morphological and biochemical effects of immunosuppressive drugs in a capillary tube assay for endothelial dysfunction

“…PGI 2 is an unstable vinyl ether formed from prostaglandin H 2 (PGH 2 ) (12). When endothelial cells are activated, prostaglandins are synthesized de novo from membrane‐released arachidonic acid (13). PGI 2 is synthesized and released during endothelial dysfunction in pulmonary hypertension, ischaemic and reperfusion injury, and malignancies (12).…”

Bradykinin as a Major Endogenous Regulator of Endothelial Function

“…An assumption of a regulatory role of HO-1on activities of other endothelial enzymes waits for experimental assessment [40]. Recently, the involvement was reported of cytosolic phosholipase A 2 in bradykinin-mediated release of PGI 2 from HUVEC [41].…”