2-Benzyloxybenzaldehyde inhibits formyl peptide-stimulated increase in intracellular Ca2+ in neutrophils mainly by blocking Ca2+ entry

2-Benzyloxybenzaldehyde (CCY1a) inhibited the formyl-Met-Leu-Phe (fMLP)-induced elevation of cytosolic [Ca2+] ([Ca2+] i) in rat neutrophils. The late plateau phase, but not the initial Ca2+ spike, of the fMLP-induced [Ca2+]i change was inhibited by CCY1a. In the absence of external Ca2+, CCY1a had no appreciable effect on either the fMLP- or cyclopiazonic acid (CPA)-induced [Ca2+]i elevation. CCY1a failed to inhibit [Ca 2+]i changes induced by N -ethylmaleimide, GEA3162, ionomycin or sphingosine, but slightly inhibited the Ca2+ signals elicited by ATP or interleukin-8 (IL-8). In a classical Ca2+ readdition protocol, addition of CCY1a after cell activation strongly inhibited the [Ca2+]i response to fMLP, whilst that to CPA was only slightly reduced. CCY1a nearly abrogated the fMLP-stimulated Mn2+ influx but was less effective on the CPA-induced response. CCY1a attenuated the levels of tyrosine-phosphorylated bands in the 70-85 kDa molecular mass range. CCY1a had no effect on the basal [Ca2+]i level, the pharmacologically isolated plasma membrane Ca2+-ATPase activity or on the mitochondrial membrane potential. Thus, CCY1a blocks fMLP-induced Ca 2+ entry into neutrophils probably by blocking the relevant Ca 2+ channel directly or, alternatively, indirectly through the attenuation of tyrosine phosphorylation of some cellular proteins.