Platelet-activating factor effects on bovine pulmonary artery endothelial cells.

Abstract

Endothelial cells (ECs) were isolated from bovine pulmonary artery and maintained in long-term culture. On reaching confluency, ECs formed a characteristic "cobblestone" monolayer. One hour after addition of 1 nM platelet-activating factor (PAF) to the growth medium, ECs underwent dramatic changes in shape from their normal polygonal morphology to more elongated spindle-shaped forms. More pronounced effects were evident in the presence of 0.1 nM phorbol-12-myristate-13-acetate (PMA), a potent activator of C kinase. It was found that at concentrations from 10(-11)-10(-7) M, PAF stimulates the phosphoinositide turnover in EC. The half-maximal activation in the release of inositol phosphates was at 10(-9) M. This finding suggested that an increase in intracellular Ca2+ concentration and activation of protein kinase C were involved in the mechanism of action of PAF on EC. The metabolic responses of EC were evaluated by measuring the activity of beta-adrenergic receptor-coupled adenylate cyclase (AC) in a crude membrane fraction and by assay of prostacyclin and thromboxane released by cultured EC. AC from control membranes was activated by isoproterenol in a dose-dependent manner (EC50 = 30 nM) from 0.8-5.5 pmol cAMP/min/mg protein. If the membranes were isolated after preincubation of ECs with 1 nM PAF or 0.1 nM PMA, the AC activity was decreased by 70 and 90%, respectively; in both cases, affinity for isoproterenol was lowered threefold (EC50 = 100 nM). Our data suggest that PAF interaction with EC leads to an apparent beta-adrenergic receptor desensitization that probably acts via a phosphorylation mechanism involving C kinase.(ABSTRACT TRUNCATED AT 250 WORDS)

Verge: A Novel Vascular Early Response Gene

“…PMA treatment of Verge-expressing RBE4 cells leads to a rapid and transient remodeling of the actin cytoskeleton and the formation of paracellular gaps PMA-induced increases in endothelial cell permeability are often associated with changes in cell shape, reorganization of the cytoskeleton, and the formation of paracellular gaps (Antonov et al, 1986;Grigorian and Ryan, 1987;Lynch et al, 1990;Garcia et al, 1992). As noted, control and Verge-expressing RBE4 cell lines form similar monolayers, and staining of nuclei confirm their cell density to be approximately equal (Fig.…”

Localization of the Platelet-Activating Factor Receptor to Rat Pancreatic Microvascular Endothelial Cells

“…Endothelial cells bind PAF, resulting in increased intracellular calcium, inositol phosphate production, and protein kinase C activity. [31][32][33] PAF synthesis by endothelial cells is elicited by a variety of inflammatory mediators including PAF itself, thrombin, and interleukin-1. 34,35 The effect of PAF on the recruitment and activation of circulating inflammatory cells is well documented.…”

Mechanism of action of platelet activating factor in the pulmonary circulation: an investigation using a novel isotopic system in rabbit isolated lung

“…Subsequent investigations have revealed that PAF can be released from other cell types including platelets (Chignard et al, 1980), neutrophils (Lynch et al, 1979;Betz & Henson, 1980), monocytes and macrophages (Arnoux et al, 1980) and endothelial cells (Camussi et al, 1983b). In addition to its effects on platelets, PAF has been shown to be a potent stimulator of other target cells including neutrophils (Goetzl et al, 1980;O'Flaherty et al, 1981), vascular endothelial cells (Handley et al, 1984;Bussolino et al, 1987;Grigorian & Ryan, 1987), vascular smooth muscle cells and bronchial smooth muscle cells (Findlay et al, 1981;Camussi et al, 1983a;Stimler & O'Flaherty, 1983; Baranes et al, 1986).…”