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Scientific article
English

Characterization of receptor-mediated and store-regulated Ca2+ influx in human neutrophils

Published inBiochemical journal, vol. 297 ( Pt 3), p. 595-601
Publication date1994
Abstract

1. It is not known to what extent the emptying of intracellular Ca2+ stores participates in the mediation of chemoattractant-induced Ca2+ influx in human neutrophils. To study this question, we compared the properties of bivalent-cation influx in response to the chemoattractant N-formyl-L-methionyl-L-leucyl-L-phenyl-alanine (f-MLP) and to the microsomal Ca(2+)-ATPase inhibitor thapsigargin. 2. The influx pathway activated by f-MLP and thapsigargin had identical properties of permeation. Mn2+ influx became saturated at around 1 mM extracellular Mn2+, whereas Ca2+ influx did not become saturated up to concentrations of 10 mM. 3. The influx of the two bivalent cations, Mn2+ and Ca2+, was activated to a similar extent and with identical kinetics of activation. 4. The Mn2+ influx activated by f-MLP and thapsigargin was blocked, with identical dose-inhibition curves, by four imidazole analogues. 5. The same relationship between the emptying of Ca2+ stores and bivalent-cation influx was observed for f-MLP and thapsigargin, with a half-maximal activation of the influx at 40% emptying of intracellular stores. 6. In conclusion, neutrophils possess a single type of Ca(2+)-influx pathway that is activated by receptor agonists and by store depletion. Receptor agonists activate this influx pathway to a large extent, if not completely, through the depletion of intracellular Ca2+ stores.

Keywords
  • Biological Transport/drug effects
  • Calcium/ metabolism
  • Humans
  • Imidazoles/pharmacology
  • Kinetics
  • Manganese/metabolism
  • N-Formylmethionine Leucyl-Phenylalanine/pharmacology
  • Neutrophils/drug effects/ metabolism
  • Receptors, Cell Surface/drug effects/ metabolism
  • Terpenes/pharmacology
  • Thapsigargin
Citation (ISO format)
DEMAUREX, Nicolas et al. Characterization of receptor-mediated and store-regulated Ca2+ influx in human neutrophils. In: Biochemical journal, 1994, vol. 297 ( Pt 3), p. 595–601.
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ISSN of the journal0264-6021
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