Figure 3
From: Two novel, putative mechanisms of action for citalopram-induced platelet inhibition
Citalopram inhibits neutrophil functions, despite preserved calcium store release. (a,b) Calcium (Ca2+) store release was monitored in Fura-2-loaded neutrophils, stimulated with 1 µM platelet-activating factor (PAF). (a) Example traces demonstrate PAF-induced increases in the cytosolic concentration of Ca2+ ([Ca2+]cyt). (b) Neutrophils were pre-incubated for approximately 5 min with citalopram (0, 10, 20, 50, 100, 200 & 500 µM) prior to the addition of PAF. The maximum increase in [Ca2+]cyt following PAF addition (Max. Δ[Ca2+]cyt) was recorded (N = 6 blood donors). (c) Neutrophils were pre-incubated with (+) or without (−) citalopram (200 µM) for approximately 5 min, followed by either no stimulation (−) or stimulation (+) with 1 µM PAF for 1 min. Rap1-GTP was isolated and quantified using densitometry following SDS-PAGE and Western blotting (N = 4 blood donors. Different donors are indicated by different symbols and the mean by ×). (d) Representative histograms, measuring antibody binding to the active epitope of αM (CD11b) in either unstimulated or PAF-stimulated neutrophils (citalopram = 0 or 100 µM, PAF = 1 µM). (e,f) A range of citalopram concentrations (0, 5, 10, 20, 50, 100, 200 & 500 µM) were used to create concentration-response curves for the effects of citalopram on (e) monoclonal antibody binding to CD11b and (f) neutrophil adhesion to fibrinogen (N = 6 blood donors). Dashed line (mean) and grey area (±SEM) indicate (e) αMβ2 activation or (f) fibrinogen-binding in unstimulated neutrophils.
