macrophages (NR8383)

Abstract: Ca2 + mobilization in the rat alveolar mac-rophage cell line NR8383 was examined with the Ca2 +-sensitive fluorescent probe Fura-2. AlP and norepinephrine elicited a 108 and 46 % increase, respectively, in cytosolic free Ca2 + concentration ((Ca2 ii). Acetyicholine, nicotine, isoproterenol, sub-stance P, and vasoactive intestinal polypeptide did not alter ICa24]j. Inositol 1,4,5-trisphosphate (1P3) for-mation was also activated by ATh The carbohydrate-rich cell wall preparation, zymosan, induced a grad-ual 1Ca2 + increase only in the presence of external f2 but did not activate 1P3 formation. This increase was abolished by laminarin and by removal of extra-cellular Ca2, suggesting that the ICa2 4Jj increase was activated by -g1ucan receptors and mediated by Ca2 influx. This influx was significantly reduced by SKF96365, but not by nifedipine, w-conotoxin GVIA, w-agatoxin WA, 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