Inhibitors of the arachidonic acid cascade dissociate 48/80-induced Ca2+ influx and Ca2+ release in mast cells

Abstract

Effects of inhibitors of the arachidonic acid cascade on Ca2+ release from intracellular stores and Ca2+ influx through the plasma membrane during stimulus-secretion coupling were examined using rat peritoneal mast cells loaded with fura-2. Compound 48/80 (48/80) was used as a secretagogue. A phospholipase inhibitor, p-bromophenacyl bromide (PBPB), or a lipoxygenase inhibitor, nordihydroguaiaretic acid (NDGA), inhibited the 48/80 (1 microgram/ml)-induced release of histamine, Ca2+, and Mn2+ influxes, but the cyclooxygenase inhibitor, indomethacin (approximately 50 microM), inhibited neither Ca2+ nor Mn2+ influxes. The Ca2+ release induced by 1 microgram/ml of 48/80 was little inhibited by PBPB, NDGA, or indomethacin. The Ca2+ release was activated and saturated with lower concentrations of 48/80 than was the Ca2+ influx. The percent inhibition of the Ca2+ release by 25 microM PBPB was increased by lowering the concentration of 48/80, but NDGA (10 microM) did not inhibit the Ca2+ release induced by low concentrations of 48/80 (0.03-0.1 microgram/ml). These results suggest that activation of the Ca2+ release and the Ca2+ influx were differently regulated and that full activation of Ca2+ influx needs the arachidonic acid cascade produced by higher concentrations of 48/80 than does the Ca2+ release. Lipoxygenase metabolites of arachidonic acid are potential modulators of the Ca2+ influx.

Characterization and modulation of canine mast cell derived eicosanoids

“…Consistent with previous work (Kuno et al, 1993), NDGA blocked mast cell degranulation. Other studies have shown that piroxicam, meloxicam, NS-398 (COX-2 inhibitor) and acetylsalicylic acid (aspirin, a COX-1/COX-2 inhibitor) treatment can prevent rat mast cells from releasing histamine following antigen-dependent (IgE) mediated stimulation (Grosman, 2007).…”

Cytochrome P450 mono‐oxygenase‐regulated signalling of Ca2+ entry in human and bovine endothelial cells.

“…In isolated rat hepatocytes (Karara, Breyer, Falck & Capdevila, 1991), pituitary cells (Snyder, Lattanzio, Yadagiri, Falck & Capdevila, 1986), parotid cells (Snowdowne, Rosenoer, Yu & Cashman, 1989) and epithelial cells (Madhun, Goldthwait, McKay, Hopfer & Douglas, 1991), 5,6-EET increases [Ca2+], due to the direct stimulation of Ca2+ entry. Additional data provided evidence for a cyclo-oxygenase-related Ca2+ release with higher concentrations of 5,6-EET (Kuno, Kawawaki, Shibata & Gotani, 1993). Our findings that 5,6-EET failed to increase [Ca2+]i in Ca2+-free solution and that cyclooxygenase inhibition did not affect 5,6-EET-induced Ca2+ entry strongly suggest a direct stimulation of endothelial Ca2+ entry by this P450 MO product (Fig.…”

“…In endothelial cells, Goligorsky, Menton, Laszlo & Lum (1989) provided strong evidence for the involvement of phospholipase A2 activation in thrombin-induced sustained Ca2+ entry. A key role of phospholipase A2 stimulation for agonist-stimulated Ca2+ entry was also described in mast cells (Kuno et at. 1993).…”

“…In agreement with these reported effects of 5,6-EET, the intracellular second messenger which is proposed to be responsible for Ca2+ entry stimulation in Xenopus oocytes was also shown to stimulate K+ channels (Parekh et al 1993). Thus, 5,6-EET fulfills all the criteria of the reported nature and properties of the intracellular messenger of 'store depletion-activated Ca2+ entry' in non-excitable cells: it is a low molecular weight, labile compound Parekh et al 1993; this study); it is synthesized by a P450-containing enzyme (P450 MO) at the microsomal membrane (for review see Alvarez et al 1991; this study); it depends on phospholipase A2 activity (Goligorsky et al 1989;Kuno et al 1993); it is diffusible (Parekh et al 1993); its stability and half-life may be influenced by intracellular pH (Thuringer, Diarra & Sauve, 1991); as an epoxycompound it is sensitive to oxidant stress (Schilling & Elliott, 1992); and, most importantly, 5,6-EET activates Ca2+ entry.…”

Proteinase-Activated Receptor (PAR)-1 and -2 Agonists Induce Mediator Release from Mast Cells by Pathways Distinct from PAR-1 and PAR-2

“…The fura-2 acetoxymethyl ester was dissolved in dimethyl sulfoxide to a concentration of 1 mM. Purified peritoneal mast cells (10 6 cells/ml) or HEK293 (10 6 cells/ml) were incubated with a final concentration of 1 M fura-2 in bovine serum albumin (0.1%)-HEPES buffer for 30 min at 37°C as described previously (Kuno et al, 1993). The cells were washed twice in HEPES buffer by centrifugation (150g, 4°C, 5 min), to remove the fura-2 that had not been taken up into the cell.…”