BALTIMORE—Researchers at The Johns Hopkins University and Yale University have discovered that a specialized receptor, normally found in the nose, is also in blood vessels throughout the body, sensing small molecules created by microbes that line mammalian intestines, and responding to these molecules by increasing blood pressure. The finding suggests that gut bacteria are an integral part of the body’s complex system for maintaining a stable blood pressure.
A description of the research, conducted in mice and test tubes, appeared online Feb. 11 in the journal Proceedings of the National Academy of Sciences.
“The contribution that gut microbes apparently make to blood pressure regulation and human health is a surprise," said Jennifer Pluznick, PhD, assistant professor of physiology at the Johns Hopkins University School of Medicine. “There is still much to learn about this mechanism, but we now know some of the players and how they interact," she added.
Pluznick said that several years ago, thanks to a “happy coincidence," she found—in the kidney—some of the same odor-sensing proteins that give the nose its powers. Focusing on one of those proteins, olfactory receptor 78 (Olfr78), her team specifically located it in the major branches of the kidney’s artery and in the smaller arterioles that lead into the kidney’s filtering structures. Olfr78 also turned up in the walls of small blood vessels throughout the body, she says, particularly in the heart, diaphragm, skeletal muscle and skin.
To figure out which molecules bind and activate Olfr78, the scientists programmed cells to have Olfr78 protein receptors on their surface. They also gave these same cells the ability to start a light-producing chemical reaction whenever Olfr78 is activated. By adding different cocktails of molecules to the cells and measuring the light the cells produced, they homed in on a single mixture that activated Olfr78. They then tested each component in that mix and found that only acetic acid (a.k.a. vinegar) bound Olfr78 and caused the reaction.