August 1, 2012

Scientists Answer: Where Do Cold Feet Come From?

Michael Harper for - Your Universe Online

Cold feet are often equated to cowardice or second-thoughts when it comes to making a life-changing decision, such as going through with a marriage. Cold feet can also be more than just a joke people tell to be folksy. In fact, many people complain about their cold feet or the cold feet of a partner. Now, some physiologists have set their brains about figuring out why some people constantly have cold feet, saying a biological mechanism in a person´s feet might be to blame.

Scientists led by Selvi C. Jeyaraj of the Research Institute at Nationwide Children´s Hospital have conducted the study and have found an interaction between a series of molecules and receptors on muscle cells could give many people the chills in their toes.

Combining their study with that of an editorial by Martin C. Michel of Johannes Gutenberg University in Mainz, Germany, and Paul A. Insel of the University of California at San Diego, this new research finds contributors to cold feet and even finds that nearly everyone has experienced this condition at one point in their life. Some are plagued by it with some frequency, a symptom which could point to a more serious condition, such as Raynaud´s disease.

This new article, aptly titled, “Cyclic AMP-Rap1A Signaling Activates RhoA to Induce a2C-Adrenoceptor Translocation to the Cell Surface of Microvascular Smooth Muscle Cells” will appear in an upcoming issue of the American Journal of Physiology - Cell Physiology.

An accompanying editorial with a similar title, “Can You Blame Cold Feet on Epac (and Rap1A)? Focus on “Cyclic AMP-Rap1A Signaling Activates RhoA to Induce ?2C-adrenoceptor Translocation to the Cell Surface of Microvascular Smooth Muscle Cells,” will also be available for easy reading on the web.

In order to study how people contracted these frozen tootsies, Jeyaraj and her colleagues examined the smooth muscle cells from very small blood vessels, which they harvested from some skin biopsies and the occasional mouse tail artery.

The cells found in the biopsies and mouse tails contain receptors named a2C-AR. These receptors are responsible for constricting the blood vessels, thereby conserving heat when the temperatures drop below a certain point.

When the researchers dosed these cells with chemicals known to activate something called Rap1A either directly or indirectly through a protein called Epac, the cells moved their receptors closer to their surface, essentially rearranging the cell´s inner “skeleton,” thus the vessels constrict.

The authors of the study have said that while the series of events they noticed might be used to explain this common phenomenon, it could also be used to provide clues as to how blood flow is erroneously cut off, as often happens with Raynaud´s disease. Most with Raynaud´s disease complain of loss of circulation to their fingers and toes, especially in areas of colder weather. More serious cases of Raynaud´s disease, however, can lead to an atrophy of skin and muscle and even on very rare cases, gangrene.

Putting a lighter spin on the study, the authors said they´ve finally given cold-feet sufferers a hilarious response when someone complains about their chilly appendages.

“If your partner complains again about your cold feet,” say the authors, pushing up their glasses with a snort, “you have some new excuses: ℠It´s Epac´s fault!´ or ℠Rap1A should get the rap!´”

Get it?!  No, I don´t either.