Unsolved Problems, Biology 446         Albert Harris

Do Trans-Membrane Voltages Have Undiscovered Functions, Yet To Be Discovered?

(Nearly?) All the differentiated cell types in our body constantly use ATP energy to pump potassium ions through their plasma membranes, from the outside to the inside, simultaneously pumping sodium ions from the inside to the outside. As much as a third of their ATP gets used by the enzyme called the "Sodium Pump ". This voltage is proportional to the logarithm of the ratio of concentration differences (a hundred to one ratio produces twice the voltage as a ten to one ratio does.)

Having a higher concentration of potassium inside a plasma membrane, as compared with outside, when combined with the membrane being leaky to potassium ions, causes a negative voltage inside a cell relative to outside. This voltage difference is called the "Resting Potential". If a cell becomes more permeable to sodium ions, allowing them to leak inward, then the voltage inside the cell becomes positive, at least for a fraction of a second.

Many different functions are known to be served by the electrical voltages produced by diffusion gradients of concentrations of ions. Nerve impulses stimulate their own contraction by means of propagated action potentials. Egg cells (oocytes) use this same kind of propagated depolarization to prevent more than one sperm from fertilizing each egg. Before fertilization, oocytes have a resting potential; Fertilization stimulates leakage of calcium ions into oocytes; That leakage propagates all over the oocyte, causing a decrease in voltage difference; And sperm can't fuse with depolarized oocytes.

When a swimming Paramecium bumps into an external object, its resting potential depolarizes, causing calcium to leak into the cytoplasm. That, in turn, causes a reversal of the direction of the power stroke of the cilia of the paramecium, causing it to back up for about a second, until the resting potential returns to normal.

Venus Fly Trap plants use depolarization of their resting potentials to stimulate changes in osmotic pressures of some of their cells, causing closure of their trap.

Electric Eels, Electric Rays (which are called "Torpedoes", the original meaning of that word) and other kinds of electric fish use action potentials (due to synchronized increases in sodium permeability) to shock other animals. If the resting potential on one cell were a tenth of a volt, and an animal had a thousand of these cells stacked up on top of each other, and opened their sodium channels on only one side of each cell, then the action potentials will be additive. One tenth of a volt per cell, multiplied by a thousand such cells, would produce a hundred volts. In fact, as much as six hundred volts are produced by electric eels. They use this for protection, for paralyzing food animals, for detecting prey animals under the sand, and in many species for the equivalent of frog mating calls.

Although I don't believe that either telepathy or telekinesis actually occur in people or animals, I suggest that if either or both did occur, the mechanism would probably make use of some kind of resting potentials and/or action potentials. If you want to produce rapid effects, at relatively long ranges, then a good way to accomplish your goal would be to use plasma membrane voltages.

What additional functions, that nobody has discovered yet, might be accomplished by resting potentials or action potentials? Maybe osteocytes use voltages to control amounts and locations of bone formation. Please suggest some additional functions that might be served by voltages. Remember how much ATP gets constantly used up by all the two-hundred-plus differentiated cell types of the body. Surely so much energy can't be serving no function, can it? For nerves, muscles and oocytes, we know what functions are served by voltage depolarizations. It would be a major breakthrough for you to discover even just one additional function.