Boosting production of one of the body's all-purpose molecules may fix a signaling problem in the heart's blood vessels that causes them to narrow instead of widen during physical stress, a Johns Hopkins study shows.
Results will be presented at 2:30 p.m., Nov. 11 at the American Heart Association's 69th annual Scientific Sessions in New Orleans.
Researchers restored the blood vessels' normal response in four people with coronary artery disease by giving them arginine, an amino acid the body uses to make nitric oxide for many tasks, including regulating blood pressure and transmitting messages along signal pathways between cells.
Normally, nitric oxide produced by cells lining the inside of blood vessels causes coronary arteries to widen to increase blood flow to the heart and other muscles during times of stress, but the arteries constrict in people with coronary artery disease, limiting blood flow and possibly contributing to ischemia and heart attack.
Eight people, four with coronary artery disease and four without it, underwent stress tests to stimulate their sympathetic nervous system before and while receiving arginine to determine if the abnormal blood vessel response is caused in part by a defect in the signaling pathways of nitric oxide.
"These findings suggest that inappropriate coronary responses to sympathetic stimulation in people with coronary artery disease may be related to changes in the arginine-nitric oxide pathway and may be improved by increasing production of nitric oxide," says Joel Gellman, M.D., the study's lead author and a cardiology fellow.
Researchers had participants put their hands in ice water, which activated the body's sympathetic nervous system. This system increases heart and breathing rates and blood flow to the muscles, as if to prepare the body for a "fight or flight" response during times of stress or fear.
The study's other authors were Joshua M. Hare, M.D., Charles J. Lowenstein, M.D., Gary Gerstenblith, M.D., Vicki J. Coombs, M.D., Jeffrey A. Brinker, M.D., and Jon R. Resar, M.D.
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