Stimulation of Ca2+ efflux by N-formyl chemotactic peptides in guinea-pig peritoneal macrophages |
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Authors: | Masato Hirata Takafumi Hamachi Eiichi Suematsu Toshitaka Koga |
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Affiliation: | 1. The Department of Biochemistry, Faculty of Dentistry, Kyushu University 61, Fukuoka 812 Japan;2. Department of Pharmacology, Faculty of Medicine, Kyushu University 61, Fukuoka 812 Japan |
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Abstract: | Effects of N-formyl chemotactic peptides on the Ca2+ influx and efflux were investigated in guinea-pig peritoneal macrophages using an isotope tracer. fMet-Leu-Phe did not enhance the influx of 45Ca2+ into macrophages, whereas it stimulated the efflux of 45Ca2+ from macrophages at concentrations ranging from 10?10 M to 10?7 M. fMet-Met-Met and fMet-Leu also stimulated the 45Ca2+ efflux, albeit at much higher concentrations, while there was no stimulation with fMet. The mitochondrial inhibitors, oligomycin and NaN3, did not modify the 45Ca2+ efflux induced by the chemoattractants, yet they did induce the release of 45Ca2+ from the mitochondria. On the other hand, higher concentrations of the calmodulin antagonists, chlorpromazine and trifluoperazine, induced the release of 45Ca2+ from the NaN3-insensitive Ca2+ store site and mimicked the enhancement of the 45Ca2+ efflux by N-formyl chemotactic peptides. Thus, N-formyl chemotactic peptides appear to increase the levels of intracellular free Ca2+ in guinea-pig peritoneal macrophages, probably by inducing the release of Ca2+ from the NaN3-insensitive Ca2+ store site. |
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Keywords: | Macrophage Chemotactic peptide (Guinea pig) Hepes 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid EGTA To whom correspondence should be addressed. |
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