Carbonated Drinks Trigger Pain Sensors

LOS ANGELESCarbon dioxide in carbonated beverages trigger the same pain sensors in the nasal cavity as mustard and horseradish, though at a lower intensity, according to research from the University of Southern California.

According to the findings, published in the Journal of Neuroscience, the burning sensation comes from a system of nerves that respond to sensations of pain, skin pressure and temperature in the nose and mouth.

Carbonation evokes two distinct sensations," said Emily Liman, senior author. It makes things sour, and it also makes them burn. We have all felt that noxious tingling sensation when soda goes down your throat too fast. What we did not know was which cells and which molecules within those cells are responsible for the painful sensation we experience when we drink a carbonated soda."

By flowing carbonated saline onto a dish of nerve cells from the sensory circuits in the nose and mouth, the researchers found that the gas activated only a particular type of cell. The cells that responded to CO2 were the same cells that detect mustard. Those cells, which express a gene known as TRPA1, serve as general pain sensors.

Cells from mice missing the TRPA1 gene showed a greatly reduced response" to carbon dioxide, while adding the TRPA1 genetic code to CO2-insensitive cells made them responsive to the gas.