Nanosecond electric pulse-induced calcium entry into chromaffin cells

Bioelectrochemistry · 2008 · Unclear · Low evidence

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UnclearLow evidencePaper 6745

Study snapshot

PublicationBioelectrochemistry · 2008

Study typein_vitro

Reported directionUnclear

Evidence ratingLow

Abstract

Electrically excitable bovine adrenal chromaffin cells were exposed to nanosecond duration electric pulses at field intensities ranging from 2 MV/m to 8 MV/m and intracellular calcium levels ([Ca(2+)](i)) monitored in real time by fluorescence imaging of cells loaded with Calcium Green. A single 4 ns, 8 MV/m pulse produced a rapid, short-lived increase in [Ca(2+)](i), with the magnitude of the calcium response depending on the intensity of the electric field. Multiple pulses failed to produce a greater calcium response than a single pulse, and a short refractory period was required between pulses before another maximal increase in [Ca(2+)](i) could be triggered. The pulse-induced rise in [Ca(2+)](i) was not affected by depleting intracellular calcium stores with caffeine or thapsigargin but was completely prevented by the presence of EGTA, Co(2+), or the L-type calcium channel blocker nitrendipine in the extracellular medium. Thus, a single nanosecond pulse is sufficient to elicit a rise in [Ca(2+)](i) that involves entry of calcium via L-type calcium channels.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typein_vitro

Effect directionunclear

PopulationBovine adrenal chromaffin cells (electrically excitable)

Sample sizeNot supplied

Exposuresingle 4 ns pulse; multiple pulses also tested

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

Chromaffin cells exposed to nanosecond electric pulses (2–8 MV/m) showed a rapid, short-lived increase in intracellular calcium after a single 4 ns, 8 MV/m pulse, with response magnitude dependent on field intensity. The calcium rise was unaffected by depletion of intracellular stores (caffeine or thapsigargin) but was prevented by extracellular EGTA, Co2+, or the L-type calcium channel blocker nitrendipine, consistent with calcium entry via L-type channels.

Outcomes measured

Intracellular calcium levels ([Ca2+]i) measured by fluorescence imaging (Calcium Green)
Dependence of calcium response on electric field intensity
Effect of pulse number and refractory period on calcium response
Role of intracellular calcium stores vs extracellular calcium entry
Involvement of L-type calcium channels (pharmacologic blockade)

Limitations

In vitro cell model (bovine adrenal chromaffin cells); generalizability to in vivo exposures not addressed in abstract
No sample size or replication details provided in abstract
Exposure described as high-intensity nanosecond pulses; relevance to typical environmental/consumer EMF exposures not stated

View raw extracted JSON

{
  "study_type": "in_vitro",
  "exposure": {
    "band": null,
    "source": "nanosecond electric pulses",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "single 4 ns pulse; multiple pulses also tested"
  },
  "population": "Bovine adrenal chromaffin cells (electrically excitable)",
  "sample_size": null,
  "outcomes": [
    "Intracellular calcium levels ([Ca2+]i) measured by fluorescence imaging (Calcium Green)",
    "Dependence of calcium response on electric field intensity",
    "Effect of pulse number and refractory period on calcium response",
    "Role of intracellular calcium stores vs extracellular calcium entry",
    "Involvement of L-type calcium channels (pharmacologic blockade)"
  ],
  "main_findings": "Chromaffin cells exposed to nanosecond electric pulses (2–8 MV/m) showed a rapid, short-lived increase in intracellular calcium after a single 4 ns, 8 MV/m pulse, with response magnitude dependent on field intensity. The calcium rise was unaffected by depletion of intracellular stores (caffeine or thapsigargin) but was prevented by extracellular EGTA, Co2+, or the L-type calcium channel blocker nitrendipine, consistent with calcium entry via L-type channels.",
  "effect_direction": "unclear",
  "limitations": [
    "In vitro cell model (bovine adrenal chromaffin cells); generalizability to in vivo exposures not addressed in abstract",
    "No sample size or replication details provided in abstract",
    "Exposure described as high-intensity nanosecond pulses; relevance to typical environmental/consumer EMF exposures not stated"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "nanosecond electric pulses",
    "chromaffin cells",
    "intracellular calcium",
    "Calcium Green",
    "electric field intensity",
    "L-type calcium channels",
    "nitrendipine",
    "EGTA",
    "Co2+",
    "caffeine",
    "thapsigargin"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1016/j.bioelechem.2008.02.003
PubMed: 18407807

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