Most people know that nerves work by passing electrical currents from cell to cell. But you might be surprised to learn that no one knows exactly how anesthetics stop nerves from carrying pain signals.
That’s why two scientists believe that we really don’t know how nerves work after all.
According to their controversial theory, electricity is just a side effect of how nerves really operate: by conducting high-density waves of pressure that resemble sound reverberating through a pipe.
“Nerves are supposed to work like a series of electrical transistors,” said Andrew Jackson, a physicist at the Niels Bohr Institute in Copenhagen, Denmark. “This picture is at best flawed.”
If correct, Jackson and Thomas Heimburg, a Niels Bohr biophysicist and co-author of a recent paper describing their theory, would turn a long-held (and Nobel Prize-winning) theory on its head.
Alan Hodgkin and Andrew Huxley won the Nobel Prize in physiology or medicine in 1963 for describing the electric transmission of impulses along nerves — a now widely accepted theory known as the Hodgkin-Huxley model.
But Jackson and Heimburg say that the inability to explain how anesthesia works, combined with other counterintuitive aspects of the theory, mean that nerves don’t rely on electricity to carry messages.
For example, the Hodgkin-Huxley model still hasn’t accounted for observations made a century ago by scientists Hans Meyer and Charles Overton. They demonstrated that the strength of an anesthetic could be predicted by its solubility in olive oil rather than its chemical structure. The more soluble the anesthetic, the stronger it was.
Since olive oil is similar to the lipid molecules that make up nerve cells, Jackson and Heimburg started questioning the generally accepted belief that anesthetics block electrical pulses by fitting themselves into pain receptors on cells. That seems next to impossible, they said, because anesthetic molecules come in many shapes and sizes, and it’s difficult to imagine that they all happen to physically fit into all receptors.
“That is about as likely as tossing a coin 1,000 times and having it come down heads every time,” Jackson said.
Their theory, published in the Biophysical Journal, explains how nerves and anesthetics work as follows: Nerves are made of lipids that are liquid at body temperature. A yet-to-be-defined mechanism creates high-pressure, semisolid waves that move through the cells, delivering messages.
Anesthetics, they suggest, lower the temperature at which lipids become solid, making it difficult for the waves to form, thereby preventing nerves from sending pain signals. They also suggest that as the waves travel, they change the shape of the cell membrane, producing the electrical pulse that scientists currently mistake for the primary function of nerve cells.
I am extremely skeptical about this. But the reason I’m posting is that I think it’s awesome that people are challenging accepted ideas and assumptions, and doing research to back it up.
It’s important not to let science turn into an orthodoxy, and while we regularly talk about the “facts” of science in contrast to the many pseudo-scientific memes that are around, we mustn’t let those ridiculous ideas close our minds to all controversial ideas.
The key difference is approach. If the person is using science and some common sense, then it’s worth considering. After all, many of our well established and fundamental scientific facts were considered “crazy” at one point.
So keep thinking, keep imagining, and keep testing!
Science!
(via allaboutscience)
