# One Volt per Centimetre: The Skin's Epithelial Battery and the Electric Field That Heals Wounds

> **Tissue Bioelectricity · Current of Injury**  
> Published at: https://mariuscomper.uk/un-volt-pe-centimetru/en/  
> Author: Marius Comper

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## Executive Summary & Key Figures

Intact human skin functions as a living bioelectric battery, maintaining a transepithelial potential (TEP) of **20 to 50 millivolts** via continuous asymmetric sodium ion transport.

The instant the epidermis is breached, the local short-circuit establishes an invisible lateral electric field of **1 to 2 volts per centimetre (100–200 V/m)** that guides keratinocyte migration directly toward the wound bed via *electrotaxis (galvanotaxis)* long before chemical gradients can diffuse.

- **1–2 V/cm (100–200 V/m)**: Lateral electric field gradient at the wound margin.
- **20–50 mV**: Resting transepithelial potential sustained by apical ENaC sodium channels and basolateral Na+/K+-ATPase pumps.
- **1.5–2.5 µm/min (90–150 µm/h)**: Directed keratinocyte migration velocity guided by bioelectricity.
- **48–72 hours**: Duration that a moist hydrocolloid dressing sustains the closed ionic circuit.

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## 1. The Injury Short-Circuit: Genesis of the Lateral Field

Most explanations depict wound repair as an exclusively biochemical cascade driven by cytokines. However, diffusion of large protein ligands through extracellular matrix is slow and Brownian-noise limited.

The human body deploys a permanently charged epithelial battery:
1. In the *stratum granulosum* and *stratum spinosum*, cells pump sodium ions ($Na^+$) from the external surface inward.
2. Paracellular tight junctions provide an electrical resistance of ~100 kΩ·cm², maintaining a transepithelial potential (TEP) of 20–50 mV.
3. A cut drops local resistance to < 1.5 kΩ·cm², and the potential at the wound bed collapses to 0 V (cathode).
4. The voltage difference between the cut margin (0 mV) and adjacent intact tissue (30–40 mV) generates a radial lateral electric field ($E = -\nabla V$) of **100–200 V/m (1–2 V/cm)**.

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## 2. Electrotaxis: The Molecular PI3K / PTEN Switch

Epidermal keratinocytes detect electric fields as low as $10\text{ mV/mm}$ ($10\text{ V/m}$).

Under physiological gradients of 100–200 mV/mm:
- The electric field clusters **PI3K** and PIP3 messengers at the cell face oriented toward the cathode (wound).
- The phosphatase **PTEN** localizes to the trailing anodal pole.
- This spatial segregation triggers actin polymerization and filopodia extension strictly toward the cut, propelling keratinocytes at a sustained velocity of $1.5-2.5\ \mu\text{m/min}$.

When sodium transport is pharmacologically blocked (amiloride/ouabain) or an opposing external field is applied, cells lose orientation or reverse direction, fleeing the wound.

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## 3. Biophysics of Moist vs Dry Healing

- **Dry environment (air-exposed)**: water evaporates into a dehydrated scab. Electrical resistance surges >1,000-fold, isolating the surface and extinguishing the injury current ($I = V/R \to 0$). Cells are forced to tunnel beneath the eschar via slow chemotaxis.
- **Moist environment (hydrocolloid / saline)**: a conductive liquid electrolyte layer ($\sigma \approx 1.4\text{ S/m}$) preserves the closed ionic circuit for 48–72 hours, accelerating re-epithelialization by 40–50%.

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## Scientific References

1. Barker, A. T., Jaffe, L. F., & Vanable, J. W. (1982). The transcutaneous electrical potential profile in humans and its relationship to the current of injury. *American Journal of Physiology*, 242(3), R358–R366.
2. Zhao, M., Song, B., Pu, J., et al. (2006). Electrical signals control wound healing through Phosphatidylinositol-3-OH kinase-γ and PTEN. *Nature*, 442(7101), 457–460.
3. McCaig, C. D., Rajnicek, A. M., Song, B., & Zhao, M. (2005). Controlling cell behavior electrically: current views and future potential. *Physiological Reviews*, 85(3), 943–978.
4. Winter, G. D. (1962). Formation of the scab and the rate of epithelization of superficial wounds in the skin of the domestic pig. *Nature*, 193(4812), 293–294.
5. Nuccitelli, R., et al. (2003). A pulsed electric field heals dermal wounds faster in clinical trials. *Wound Repair and Regeneration*, 11(6), A18.
6. Reid, B., Song, B., McCaig, C. D., & Zhao, M. (2005). Wound healing in rat cornea: the role of electric currents. *FASEB Journal*, 19(3), 379–386.