concanavalin-a and fura-2-am

The relationship between luminol dependent chemiluminescent (LDCL) response and changes in intracellular free Ca2+ concentrations in the bovine neutrophils was evaluated. LDCL responses and changes in intracellular Ca2+ concentrations of neutrophils were clearly detected by the stimulation with opsonized zymosan (OPZ), concanavalin A(ConA), heat-aggregated IgG (H-agg.IgG) and phorbol myristate acetate (PMA). Patterns of LDCL responses and intracellular Ca2+ of neutrophils showed characteristic features for each stimulant. PMA was a weak stimulant of the intracellular Ca2+ concentration, whereas it was a strong stimulant of LDCL response. Con A strongly stimulated an increase in the intracellular Ca2+ concentration, but was a weak stimulant of LDCL response. LDCL response of intracellular Ca(2+)-depleted neutrophils treated with ionomycin, stimulated with each stimulant was inhibited markedly without extracellular Ca2+. The sustained phase of intracellular Ca2+ concentrations stimulated with OPZ was inhibited significantly (P < 0.05) by the preincubation with anti-CD18 antibody, whereas the transient phase of intracellular Ca2+ concentrations was not inhibited. These results indicate that LDCL response is regulated at least in part by the elevation of the intracellular Ca2+, and a rise in intracellular Ca2+ concentration, which may be mediated by specific receptors appears to be essential in the LDCL response of bovine neutrophils.

Topics: Animals; Antibodies, Monoclonal; Calcium; Cattle; CD18 Antigens; Concanavalin A; Fluorescent Dyes; Fura-2; Immunoglobulin G; In Vitro Techniques; Kinetics; Luminescent Measurements; Luminol; Neutrophils; Tetradecanoylphorbol Acetate; Zymosan

We used Fura-2 fluorometry to observe the effects of nitroglycerin (NG), isosorbide--2,5--dinitrate (ISDN) and sodium nitroprusside (NP) on basal and mitogen-induced (Con A, 25 micrograms/ml) cytoplasmic Ca++level ([Ca++]) in human blood lymphocytes. It is shown that nitrates dose-dependently decrease Con-A-induced increase in [Ca++]i. When compared for the effect on calcium metabolism, NP appeared most potent (IC50 = 4.1 x 10(-7) M). The drug action was not reported when the cells were exposed to Ca(++)-free solution. 120-min preincubation with 10(-4) M NG led to complete abolishment of the ISDN and NG effects. The results suggest that human lymphocytes may be used as an experimental model of nitrates action and mechanisms underlying tolerance to them.

Topics: Calcium; Concanavalin A; Cytosol; Dose-Response Relationship, Drug; Fluorescent Dyes; Fura-2; Humans; Isosorbide Dinitrate; Lymphocytes; Nitroglycerin; Nitroprusside; Time Factors