Superoxide generation and granule enzyme release induced by ionophore A23187: Studies on the early events of neutrophil activation

Louis Simchowitz, Isaias Spilberg, John P. Atkinson

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


The responses of isolated human peripheral neutrophils to activation by the divalent cation ionophore A23187 (4 × 10−3M to 2 × 10−5M) were studied over the course of 15 min at 37 °C. Dose-dependent increases were noted in the following A23187-induced functions: (1) membrane depolarization, as assessed by a fluorescent cyanine dye, (2) altered membrane permeability to 22Na+ and 45Ca2+, (3) increased intracellular levels of cAMP, (4) O2 generation, and (5) granule enzyme release. Membrane depolarization and the cAMP response preceded the onset of O2 generation and exocytosis, which began after a latency period of approximately 30 sec. All five functions induced by 2 × 10−5M A23187 required ~1 mM Ca0 for optimal expression and declined substantially as Ca0 was reduced towards a nominal O mM. In contrast, the Na+ ionophore gramicidin D (0.1 to 10 μg/ml) caused cell depolarization and increased 22Na+ uptake but did not stimulate 45Ca2+ uptake, the cAMP response, O2 generation, or exocytosis of granule constituents. The observations dissociate membrane depolarization and altered Na+ permeability, on the one hand, from a Ca2+ influx, cAMP response, O2 release, and exocytosis on the other. These studies, then, are consistent with a hypothesis that a Ca2+ influx is required for the biologic expressions of cell activation.

Original languageEnglish
Pages (from-to)408-424
Number of pages17
JournalJournal of Laboratory and Clinical Medicine
Issue number3
StatePublished - Jan 1 1980


  • (O
  • 3
  • 3′-dipropylcarbocyanine [diS-C-(5)]
  • 5′-cyclic monophosphate
  • 5′-cyclic monophosphate
  • Ca
  • DMSO
  • EDTA
  • FMLP
  • LDH
  • Mg
  • adenosine 3′
  • cAMP
  • cGMP
  • dimethyl sulfoxide
  • ethylenediamine tetraacetate
  • extracellular Ca concentration
  • extracellular Mg concentration
  • formyl-methionyl-leucyl-phenylalanine
  • guanosine 3′
  • lactic dehydrogenase
  • superoxide radical


Dive into the research topics of 'Superoxide generation and granule enzyme release induced by ionophore A23187: Studies on the early events of neutrophil activation'. Together they form a unique fingerprint.

Cite this