Action Potentials in Macrophages Derived from Human Monocytes

McCann, Frances V.; Cole, James J.; Guyre, Paul M.; Russell, Jerome A. G.

doi:10.1126/science.6823563

Cited by 50 publications

(27 citation statements)

References 9 publications

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“…5B) -activated K ϩ channels may explain the initial depolarization and subsequent hyperpolarization observed in mouse macrophages (8) and the transient outward current followed by a sustained inward current reported in human alveolar macrophages (10) following Fc␥R activation. Indeed, earlier microelectrode studies reporting action potentials in human monocyte-derived macrophages (25) may also be explained along similar lines.…”

Section: Discussionmentioning

confidence: 77%

Fcγ Receptor I Activation Triggers a Novel Ca2+-activated Current Selective for Monovalent Cations in the Human Monocytic Cell Line, U937

Floto

Somasundaram

Allen

et al. 1997

Journal of Biological Chemistry

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Section: Discussionmentioning

confidence: 77%

Fcγ Receptor I Activation Triggers a Novel Ca2+-activated Current Selective for Monovalent Cations in the Human Monocytic Cell Line, U937

Floto

Somasundaram

Allen

et al. 1997

Journal of Biological Chemistry

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“…Cultured macrophages derived from human monocytes have an excitable membrane (1) and changes in membrane potential are among the earliest detectable events upon stimulation of phagocytosis (2). So far, direct membrane potential or current measurements have been made with the use of intracellular glass microelectrodes (1,3,4). This type of electrode, however, seriously hampers the study of ionic currents in small cells such as macrophages (3).…”

Section: Introductionmentioning

confidence: 99%

Development of a delayed outward-rectifying K+ conductance in cultured mouse peritoneal macrophages.

Ypey¹,

Clapham²

1984

Proc. Natl. Acad. Sci. U.S.A.

119

100

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Patch clamp techniques were used to study ionic currents in cultured mouse peritoneal macrophages. Whole-cell voltage clamp studies of cells 1-5 hr after isolation showed only a high-resistance linear membrane. After 1 day in culture, 82 of 85 cells studied had developed a voltage-and time-dependent potassium (K+) conductance similar to the delayed outward rectifier in nerve and muscle cells. The current activated when the membrane was depolarized above -50 mV. The sigmoidally rising current rose to a peak at a rate that increased with depolarization. Inactivation proceeded exponentially with a time constant of -450 ms. Recovery from inactivation was slow (r = 12 s). The reversal potentials for varying extracellular K+ concentrations followed the Nernst predictions for a KV-specific channel. The conductance was blocked by extracellular 4-aminopyridine and by intracellular tetraethylammonium chloride, barium, and cesium. Singlechannel K+ currents comprising this net current had a conductance of 16 pS, exhibited bursting behavior, and inactivated with time. No inward currents were ever detected in macrophages cultivated for up to 4 days. Short-term exposure to chemoattractant and transmitter agents failed to activate an inward current. Macrophages may change their membrane electrophysiological properties depending on their state of functional activation. We postulate that the K+ conductance develops prior to depolarizing conductances involved in the macrophage's immunological functions.Ionic membrane currents in macrophages may serve as signals between membrane-ligand interactions and cellular reactions such as phagocytosis of microorganisms. Cultured macrophages derived from human monocytes have an excitable membrane (1) and changes in membrane potential are among the earliest detectable events upon stimulation of phagocytosis (2). So far, direct membrane potential or current measurements have been made with the use of intracellular glass microelectrodes (1,3,4). This type of electrode, however, seriously hampers the study of ionic currents in small cells such as macrophages (3). Therefore, we have applied the patch clamp technique (5), which allows high resolution of ionic currents in small cells (diameter, <20 jtm) up to high frequencies (<10 kHz). We report here that on the first day after isolation, mouse peritoneal macrophages develop an outward-rectifying potassium (Kt) conductance, similar to the delayed rectifier in nerve (6-8) and skeletal muscle membranes (9). The single channels underlying this conductance exhibit a linear current-to-voltage relationship and have a conductance of about 16 pS. Since Nat or Ca2t currents could not be detected in these cells up to 4 days after isolation, we suggest that this conductance is the first conductance expressed in the development of macrophage excitability. MATERIALS AND METHODSResident macrophages were isolated from the peritoneal cavity of male NMRI mice of 20-22 g (Charles River Wiga GmbH, Sulzfeld, Federal Republic of Germany) as described elsewhere ...

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“…Early measurements of Vm were misinterpreted as action potentials (McCann et al, 1983). Values of around -75 mV have been recorded (McCann et al, 1987;Gallin & Sheehy, 1985;Buisman et al, 1988), and it has been suggested that time of adherence is not important because rapid hyperpolarization was observed after only 30 minutes post-adhesion (Gallin & Sheehy, 1985).…”

Section: Macrophage Passive Membrane Propertiesmentioning

confidence: 99%

Electrical Membrane Properties in the Model Leishmania-Macrophage

Camacho¹

2012

Patch Clamp Technique

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Action Potentials in Macrophages Derived from Human Monocytes

Cited by 50 publications

References 9 publications

Fcγ Receptor I Activation Triggers a Novel Ca2+-activated Current Selective for Monovalent Cations in the Human Monocytic Cell Line, U937

Fcγ Receptor I Activation Triggers a Novel Ca2+-activated Current Selective for Monovalent Cations in the Human Monocytic Cell Line, U937

Development of a delayed outward-rectifying K+ conductance in cultured mouse peritoneal macrophages.

Electrical Membrane Properties in the Model Leishmania-Macrophage

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