CSU researcher examining chemical that could improve circulation, tissue oxygen levels

Steven Garcia and Frank Dinenno in lab

Frank Dinenno, right, demonstrates ultrasound techniques to one of his students, Steven Garcia, last spring. Photo by Bill Cotton

A CSU researcher is taking a closer look at a chemical that seems to be critical to the dilation of blood vessels and oxygen delivery in the body — and it could prove to be a game-changer for older adults, diabetics and others with circulation problems.

For years, Professor Frank Dinenno has studied the chemical adenosine triphosphate, or ATP, and its role in controlling how vessels expand and contract during exercise. The director of CSU’s Human Cardiovascular Physiology Laboratory in the Department of Health and Exercise Science, Dinenno describes ATP as a chemical released in the body when oxygen levels in red blood cells drop — such as when someone contracts their muscles when exercising. To help increase oxygen delivery to the active muscles, the ATP released by red blood cells causes blood vessels to expand, allowing for more blood flow and increasing tissue oxygen levels.

Frank Dinenno
Frank Dinenno

Now Dinenno, also a faculty member in the School of Biomedical Engineering, has launched a new study in which he’ll assess the true power of ATP by blocking its ability to bind to receptors along the lining of blood vessels. If the vessels don’t expand when those receptors are blocked, it will confirm that ATP plays a crucial role in dilation, and opens the door to the possibility that increasing circulating ATP could be a therapeutic target to enhance tissue blood flow and oxygen levels in various populations.

How key is ATP?

“If we can find a way to block the receptors that ATP binds to and we see very little dilation as a result, it would be really cool,” he says. “Can we knock it out completely, and is ATP really that important? At this point, nobody knows. I’m going to enjoy this project. Someone needs to do this, and we’re one of the only labs in the world capable of doing it.”

Typically, he says, older adults and diabetics exhibit low levels of circulating ATP, dilation and oxygen delivery to peripheral tissues. For example, diabetics often experience problems with their extremities because of poor circulation. ATP may become a key to enhancing their blood flow, if Dinenno’s hypothesis holds true.

His research project is supported by a three-year, $412,612 grant from the Institute on Aging at the National Institutes of Health. Dinenno is recruiting about 60 healthy young adults between the ages of 18 and 35, and about 20 healthy older adults above the age of 65. He’ll test the ability to block ATP by giving his subjects an injection of pyridoxine  (vitamin B-6) or pyridoxal 5’-phosphate (the active form of vitamin B-6), which are believed to block the purinergic receptors along the lining of the blood vessel called the endothelium. Then his lab will introduce ATP and monitor dilation, which can be affected by a variety of factors. The research team will also test relatives of ATP that have different levels of phosphate: adenosine diphosphate, adenosine monophosphate and adenosine.

Given the crucial role that the endothelium plays in vascular health, Dinenno’s findings could also have significant implications for people with high cholesterol, cardiovascular disease, high blood pressure and atherosclerosis. He’ll be working closely on the project with Dr. Scott Fahrner, who was recently hired to be the medical director of research for the Human Performance Clinical Research Laboratory.

Those interested in participating in the study can send an email to chhs-hes_cardiovascular_lab@mail.colostate.edu. The Department of Health and Exercise Science is part of CSU’s College of Health and Human Sciences.