Release of calcium from membranes and its relation to phagocytotic metabolic changes: A fluorescence study on leukocytes loaded with chlortetracycline

Metabolic requirements for maintenance of the chlortetracycline‐labeled pool of membrane‐bound calcium in human neutrophils

“…N-ethylmaleimide inhibited only lysosomal enzyme release. 2-Deoxyglucose is a glycolytic inhibitor and therefore Con A, the characteristic decrease in fluorescence which 12' has been attributed to the mobilization of intracellular calcium Naccache et al, 1979;Takeshige et al, 1980) was diminished. Thus, the release of membrane-bound calcium into the cytosol, wherein it might serve as a second…”

Neutrophil Degranulation

“…In fact, results of some very recent studies suggest that release of calcium from plasma membrane storage sites into the cytosol of neutrophils is crucial for degranulation (and other) responses to soluble and insoluble stimuli. For example, several investigators have demonstrated that neutrophils labeled with chlortetracycline (which forms fluorescent complexes with membrane-bound calcium and magnesium) rapidly lose fluorescence when exposed to a variety of soluble stimuli (Naccache et al, 1979b,c;Takeshige et al, 1980;Smolen and Weissmann, 1982). These findings have been interpreted as indicating translocation of calcium in stimulated neutrophils from membrane sites to the cytoplasm.…”

Monitoring of cytosolic free Ca2+ in C5a-stimulated neutrophils: loss of receptor-modulated Ca2+ stores and Ca2+ uptake in granule-free cytoplasts.

“…These changes are mimicked or modulated, or both, by Ca2+ ionophores and intracellular Ca2+ antagonists (6)(7)(8)(9)(10) and are associated with increased 45Ca uptake (5, [11][12][13]. Thus, the concept has emerged that a variation in the cytosolic Ca2+ concentration, caused by either Ca2+ mobilization from intracellular stores or increased inward Ca2+ diffusion, might promote and, perhaps, regulate the neutrophil response to surface stimulation.…”

“…Neutrophils and cytoplasts were loaded by incubation at 370C with quin2/AM (acetoxymethyl ester of quin2, which is 2-{[2-bis(acetylamino)-5-methylphenoxy]methyl-6-methoxy-8-bis(acetylamino)}quinoline, a gift of R. Y. Tsien) in Hepes medium. The usual procedure was to add 25 AM or 10 ,uM quin2/AM to 5 x 107 cells per ml or 1 x 108 cytoplasts per ml, respectively, incubate for 15 min, then dilute 1:5 with Hepes medium containing 0.5% bovine serum albumin, and continue the incubation at 37°C for 45 min. From these stock suspensions, which were maintained at room temperature, an aliquot was withdrawn before each measurement, centrifuged for a few sec at 12,000 x g, and resuspended in 1.5 ml of Hepes medium.…”