Carbon dioxide's new-found signalling role could be applied to blood flow, birth and deafness

November 13, 2013

New research reveals exactly how the body measures carbon dioxide and suggests that far from being a metabolic waste product, it could play a key role as a biological signalling molecule.

Researchers led by Professor Nick Dale in the School of Life Sciences at the University of Warwick have shown that the body senses carbon dioxide directly through the protein Connexin 26, which acts as a receptor for the gas. Connexin 26 is better known as forming a direct channel of communication between cells. This new work shows an unexpected function for Connexin 26 -as a receptor for carbon dioxide.

The study demonstrates at a molecular level exactly how Connexin 26 interacts with carbon dioxide. This finding therefore adds carbon dioxide to the list of gaseous signalling molecules, such as nitric oxide, carbon monoxide and hydrogen sulphide already known to be active in mammals.

Given that Connexin 26 is found in many tissues and organs - and, for example, mutations in it are the commonest genetic cause of deafness - the findings could have far-reaching effects as they open up potential new ways to control physiological processes such as brain blood flow, breathing, hearing, reproduction and birth.

Carbon dioxide is the by-product of metabolism in all cells. Dissolved carbon dioxide can combine with water to increase acidity in the blood. As mammals produce carbon dioxide at a fast rate, it is vital that the body measures its levels so that breathing rates can be adjusted to exhale excess carbon dioxide and thus regulate blood pH within the narrow limits compatible with life.

Until now the body's regulation of blood acid levels was thought to be triggered by measuring pH levels of the blood. However the new findings from Warwick indicate that the body can sense carbon dioxide levels directly through Connexin 26.

Professor Nick Dale said: "Carbon dioxide is the unavoidable by-product of our metabolic system - human beings and other mammals produce huge amounts of it every day.

"The exciting implication of our study is that carbon dioxide is much more than just a waste product: it can directly signal physiological information, and our work shows the mechanism by which this happens via Connexin 26.

"As Connexin 26 is present in many tissues and organs, for example the brain, skin, inner ear, liver and the uterus during pregnancy, this discovery should herald a re-evaluation of the potential for carbon dioxide signalling in many different processes such as the control of blood flow, breathing, hearing, reproduction and birth."

Connexin 26 comprises six identical subunits. Carbon dioxide makes a chemical bond to the side chain a particular amino acid. This modified side chain can then form a bridge to a closely oriented amino acid in the adjacent subunit. A total of six carbon dioxide molecules can bind to make six bridges between subunits. These bridges force the Connexin 26 protein to alter its conformation thereby signalling the presence and concentration of carbon dioxide.
-end-
The study CO2 directly modulates connexin 26 by formation of carbamate bridges between subunits was published in the open access journal eLife. It was co-authored by Louise Meigh, Sophie Greenhalgh and David Roper of the University of Warwick and Thomas Rodgers and Martin Cann of the University of Durham.

University of Warwick

Related Blood Flow Articles from Brightsurf:

Brain regions with impaired blood flow have higher tau levels
In Alzheimer's disease, impaired blood flow to brain regions coincides with tau protein buildup.

3D ultrasound enables accurate, noninvasive measurements of blood flow
A 3D ultrasound system provides an effective, noninvasive way to estimate blood flow that retains its accuracy across different equipment, operators and facilities, according to a new study.

Blood flow recovers faster than brain in micro strokes
Work by a Rice neurobiologist shows that increased blood flow to the brain is not an accurate indicator of neuronal recovery after a microscopic stroke.

Exercise improves memory, boosts blood flow to brain
Scientists have collected plenty of evidence linking exercise to brain health, with some research suggesting fitness may even improve memory.

3D VR blood flow to improve cardiovascular care
Biomedical engineers are developing a massive fluid dynamics simulator that can model blood flow through the full human arterial system at subcellular resolution.

MRI shows blood flow differs in men and women
Healthy men and women have different blood flow characteristics in their hearts, according to a new study.

Brain blood flow sensor discovery could aid treatments for high blood pressure & dementia
A study led by researchers at UCL has discovered the mechanism that allows the brain to monitor its own blood supply, a finding in rats which may help to find new treatments for human conditions including hypertension (high blood pressure) and dementia.

Blood flow monitor could save lives
A tiny fibre-optic sensor has the potential to save lives in open heart surgery, and even during surgery on pre-term babies.

Changes in blood flow tell heart cells to regenerate
Altered blood flow resulting from heart injury switches on a communication cascade that reprograms heart cells and leads to heart regeneration in zebrafish.

Blood flow command center discovered in the brain
An international team of researchers has discovered a group of cells in the brain that may function as a 'master-controller' for the cardiovascular system, orchestrating the control of blood flow to different parts of the body.

Read More: Blood Flow News and Blood Flow Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.