To study the membrane phospholipid rearrangement that appears after ultrashort pulse exposure and to evaluate the electrophysical boundaries of the pulsed field exposures that produce membrane phospholipid translocation.
Phosphatidylserine (PS) is a key phospholipid component of eucaryotic cell membrane and found almost exclusively on inner leaflet of the plasma membrane lipid bilayer in normal healthy cells. PS externalization is an important physiological signal.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
20 Hz
Modulation type:
pulsed
Exposure duration:
50 pulses
|
|
|
Exposure 2:
2 Hz–2 kHz
Modulation type:
pulsed
Exposure duration:
50 pulses
|
|
Exposure 3:
Modulation type:
pulsed
Exposure duration:
not given in the article
|
|
Exposure 4:
Modulation type:
pulsed
Exposure duration:
not given in the article
|
|
| Frequency | 20 Hz |
|---|---|
| Type | |
| Exposure duration | 50 pulses |
| Modulation type | pulsed |
|---|---|
| Pulse width | 7 ns |
| Rise time | 2 ns |
| Exposure source |
|
|---|---|
| Setup | Cells were placed in a rectangular channel (100 µm wide, 30 µm deep, 12 mm long) with gold plated electrode walls microfabricated on a glass microscope slide |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 4,000 kV/m | maximum | - | - | 0, 1, 1.5, 2.5, 3.5, 4 MV/m |
| Modulation type | pulsed |
|---|---|
| Pulse width | 7 ns |
| Rise time | 2 ns |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 2,500 kV/m | - | - | - | - |
| Frequency |
|
|---|---|
| Type | |
| Exposure duration | not given in the article |
| Modulation type | pulsed |
|---|---|
| Pulse width | 1 µs |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 1,000 kV/m | - | - | - | with 30 µJ/pulse |
| Frequency |
|
|---|---|
| Type | |
| Exposure duration | not given in the article |
| Modulation type | pulsed |
|---|---|
| Pulse width | 30 ns |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 2,500 kV/m | - | - | - | with 5µJ/pulse |
1.5 MV/m pulses produce an intermediate level of PS translocation, above background but less than maximum response observed with higher amplitudes, indicating that the field threshold for PS externalization with 7 ns pulses lies between 1.0 and 1.5 MV/m. At higher field strengths a plateau in the response is revealed. Pulses of 2.5, 3.5, and 4.0 MV/m induce PS translocation in approximately the same fraction of the population (30-40% of the cells). Varying the pulse repetition rate over three orders of magnitude for 50 pulses, 7 ns, 2.5 MV/m exposures reveals a decline in PS externalization at 2000 Hz and an enhancement at 2 Hz.
It is also shown that nanoelectropulse-induced phosphatidylserine translocation does not require calcium in the external medium, and that the pulse regimens used in these experiments do not cause significant intra- or extracellular Joule heating.
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