If you put a tiny electrode inside almost any living cell — a neuron, a skin cell, a planarian worm cell — you will measure a voltage. The inside of the cell will be roughly seventy thousandths of a volt more negative than the outside. That difference is called the resting membrane potential, and it is one of the most universal facts in biology.
Until recently, this voltage was understood as a side-effect of the way ions are distributed across the cell membrane. A consequence. A bookkeeping detail. But over the last twenty years, a growing body of work — led in particular by Michael Levin’s lab at Tufts — has flipped the framing. The voltage is not the bookkeeping. The voltage is the message.
Why every cell holds a charge
Inside every cell, there are far more positively charged potassium ions (K+) than outside. Outside, there are more sodium ions (Na+) and chloride ions (Cl−) than inside. The membrane separating those two compartments is selectively permeable — protein channels embedded in it allow specific ions to cross at specific rates.
The mismatch is maintained, at constant metabolic cost, by a pump called the Na+/K+-ATPase. It throws three sodium ions out for every two potassium ions it pulls in, burning one ATP each cycle. The result is a stable disequilibrium: a tiny battery, in every cell, charged and waiting.
What the voltage does
Voltage shapes behaviour. In a neuron, a sudden depolarization — the inside becoming less negative — opens voltage-gated sodium channels, which lets in more sodium, which depolarizes further, which opens more channels. The resulting spike is an action potential, the unit of nervous-system communication. That part you may have learned in high-school biology.
The part you almost certainly didn’t learn: every cell uses voltage as a signal, not just neurons. Skin cells, liver cells, embryonic cells, cancer cells — all of them maintain a resting potential, all of them change it in response to development and injury, and all of them appear to read the resting potential of their neighbours.
“Voltage is not the bookkeeping. Voltage is the message.” — the bioelectric reframing
The Levin experiments
The most striking demonstration comes from planarian flatworms. Cut a planarian in half and each half regrows the missing end — head on the anterior side, tail on the posterior side — with extreme reliability. In Levin’s lab, researchers showed that the polarity of regeneration is determined by the voltage gradient across the wound, not by gene expression upstream. Change the voltage with ion-channel drugs and you can grow a two-headed planarian. Lock that voltage pattern in, and the worm will continue to regenerate two heads from any future cut, even though no gene has been edited.
This is the core of the bioelectric program: anatomical decisions are made in voltage, not in genes alone. The genome encodes the toolkit; the bioelectric pattern encodes the blueprint being followed.
Why it might matter for medicine
- Cancer. Tumour cells consistently have depolarized resting potentials. Some experiments have shown that re-polarizing tumour cells (driving them back toward normal voltage) can normalize their behaviour without killing them.
- Regeneration. If voltage encodes anatomical instructions, the right voltage pattern at the right time might trigger limb or organ regrowth in species — humans — that don’t normally regenerate.
- Aging. Resting potentials drift with age. Whether that drift is cause, consequence, or both is open. It is also a target.
What this lesson is not
It is not a settled clinical paradigm. Bioelectric medicine is, in 2026, where gene therapy was around 2005 — well past “cool experiment” and not yet at “FDA-approved.” What we have is a serious, replicable scientific program with at least one Nobel-plausible question at its centre: how does a body know what shape it’s supposed to be?
If the answer turns out to involve voltage patterns at least as much as gene expression, the implications for cancer, regenerative medicine, and aging are large. If it turns out to be a smaller story than that, you’ve still learned the universal fact that every cell in your body is a tiny charged battery, constantly signalling its neighbours in a language we’re only beginning to understand. Which, on its own, is enough.
For further reading
- Levin, M. (2014). “Molecular bioelectricity: how endogenous voltage potentials control cell behaviour and instruct pattern regulation in vivo.” Mol. Biol. Cell.
- Pai, V. P. et al. (2012). “Transmembrane voltage potential controls embryonic eye patterning in Xenopus laevis.” Development.
- Mad Sci Hub video catalog: 50 more bioelectricity lessons ·
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