Are there functional gap junctions or junctional hemichannels in macrophages?

Luiz A. Alves, Robson Coutinho-Silva, Pedro Muanis Persechini, David C. Spray, Wilson Savino, Antônio C. Campos De Carvalho

Research output: Contribution to journalArticle

66 Scopus citations

Abstract

The existence of functional gap junctions in migratory cells of the immune system is a controversial issue. In this report, we have focused on one particular cell type, namely the macrophages, because connexin-43, a protein that forms gap junctions, has been described in peritoneal macrophages and a macrophage cell line (J774), by Northern and Western blot analysis. To test whether these cell types expressed functional gap junctions, we assayed dye coupling by intracellular injection of Lucifer Yellow. We observed that nonstimulated macrophages are not coupled among themselves and did not form functional gap junctions with an epithelial cell line, which expresses functional gap junctions formed by connexin-43. Dye coupling was also not detected between macrophages previously activated by lipopolysaccharide or interferon-γ. We further examined the presence of functional coupling using the more sensitive technique of dual whole cell patch-clamp, and again, did not find electrical coupling between macrophages, consistent with the dye microinjection data. We also examined the possible presence of hemigap junction channels activated by extracellular adenosine triphosphate (ATP) using a dye uptake assay and the whole cell patch-clamp technique. Conditions expected to close gap junction hemichannels (exposure to octanol and low intracellular pH) did not decrease ATP-induced Lucifer Yellow uptake, whereas conditions expected to increase hemichannel opening either did not affect ATP permeabilization (dibutyryl adenosine monophosphate) or decreased it (zero extracellular Ca2+). Finally, in experiments using resident macrophages derived from conexin-43 knockout mice, we observed ATP induced dye uptake. Our experimental data thus indicate that macrophages in vitro do not form functional gap junctions and that the permeability pathway activated by extracellular ATP is not formed by a hemigap junction channel.

Original languageEnglish (US)
Pages (from-to)328-334
Number of pages7
JournalBlood
Volume88
Issue number1
StatePublished - Jul 1 1996
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

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  • Cite this

    Alves, L. A., Coutinho-Silva, R., Persechini, P. M., Spray, D. C., Savino, W., & Campos De Carvalho, A. C. (1996). Are there functional gap junctions or junctional hemichannels in macrophages? Blood, 88(1), 328-334.