Mechanisms involved in the cytosolic calcium ion elevation induced by activating factors in chicken and rat phagocytes
Yong, S.(Inner Mongolia Univ. of Technology, Huhehaote (China)) | Abe, A. | Kondo, Y.
The aim of the present study was to determine the mechanism of cytosolic calcium ion concentration [Casup(2+)]sub(i) elevation in chicken and rat phagocytes stimulated with phorbol myristate acetate(PMA). leukotriene Bsub(4) (LTBsub(4)), formyl-methionyl-leucyl-phenylananine (fMLP) and Saccaromyces cerevisiae culture supernatant (SCS). Pretreatment with EGTA completely suppressed the PMA-induced [Casup(2+)]sub(i) elevation in rat and chicken phagocytes, suggesting that all the [Casup(2+)]sub(i) elevation induced in the PMA-stimulated rat and chicken phagocytes was attributable to the influx of extracellular Casup(2+). On the other hand, the elevation of LTBsub(4)-, FMLP- and SCS-induced [Casup(2+)]sub(i) was only partially suppressed by ethyleneglycol-bis (beta-aminoethyl)-N,N,N',N'-tetraacetic acid ethylene (EGTA) pretreatment of phagocytes. The results indicated that two pathways of [Casup(2+)]sub(i) elevation, recruitment from the intracellular Casup(2+) store and influx of extracellular Casup(2+) are involved in the [Casup(2+)]sub(i) elevation of LTBsub(4)-, fMLP- and SCS-stimulated phagocytes. In fMLP-stimulated rat neutrophils, [Casup(2+)]sub(i) elevation showed a two-phase pattern in which the time lag between the first and second phase was approximately 1 min. The EGTA treatment of the fMLP-stimulated cells induced a reduction of the first phase level and a disappearance of the second phase. The reason for the special influence of EGTA observed in fMLP-stimulated cells is unknown, but the disappearance of the second phase of the [Casup(2+)]sub(i) may be elicited by the EGTA-induced decrease of the first phase [Casup(2+)]sub(i) elevation that depends on IPsub(3) and diacylglycerol induced by fMLP.
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