Nociceptor activation and damage by pulsed E-Fields.
11 November 2006
We assessed the capacity of ultrashort E-fields to activate rat cutaneous nociceptors. Experiments were conducted in vitro on nociceptive neurons representing hairy skin and glabrous skin. Electrical and optical recording methods were used to assess action potentials and membrane damage thresholds. Strength duration (SD) curves were formed for E-field pulses from 500 μsec to 350 ns. There were no differences in the SD time contant (taue (59 μsec) or ultrashort thresholds (129 V/cm at 350 ns) for hairy or glabrous skin nociceptors, for nociceptors with distinct geometry or for nociceptors expressing different combinations of voltage sensitive Na+ channels (TTXs and TTXr Nav) or hyperpolarization activated channels (HCN; IH).
Subthreshold activation was possible with high frequency pulsing at ultrashort durations (350 ns; 4,000 Hz). Relative to single pulse thresholds, activation threshold could be reduced over 50% by high frequency burst trains (4,000 Hz; 1-40 msec). Nociceptors were not damaged by E-field activation. Irreversible membrane disruption occurred at significantly higher field strength and varied by cell radius (3,266-4,240 V/cm, 350 ns, 40 Hz, 5 sec). Pulse frequency had no influence on acute membrane failure (10, 20, 40, 4,000 Hz; 5 sec).
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).
Nene, D., Jiang, N., Rau, K.K., Richardson, M. and Cooper, B.Y., 2006, May. Nociceptor activation and damage by pulsed E-Fields. In Defense and Security Symposium (pp. 621904-621904). International Society for Optics and Photonics.
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Category: Medical & Pharmaceutical