| Abstrakt: |
Ca2+mobilization in the rat alveolar macrophage cell line NR8383 was examined with the Ca2+‐sensitive fluorescent probe Fura‐2. ATP and norepinephrine elicited a 108 and 46% increase, respectively, in cytosolic free Ca2+concentration ([Ca2+]i). Acetylcholine, nicotine, isoproterenol, substance P, and vasoactive intestinal polypeptide did not alter [Ca2+]i. Inositol 1,4,5‐trisphosphate (IP3) formation was also activated by ATP. The carbohydraterich cell wall preparation, zymosan, induced a gradual [Ca2+]iincrease only in the presence of external Ca2+, but did not activate IP3formation. This increase was abolished by laminarin and by removal of extracellular Ca2+, suggesting that the [Ca2+]iincrease was activated by β‐glucan receptors and mediated by Ca2+influx. This influx was significantly reduced by SKF96365, but not by nifedipine, ω‐conotoxin GVIA, ω‐agatoxin IVA, or flunarizine. These results suggest that release of intracellular Ca2+in NR8383 cells is regulated by P2‐purinoceptors and that zymosan causes Ca2+influx via a receptor‐operated pathway. J. Leukoc. Biol.62: 341–348; 1997. |
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