Dr. Calvert and Dr. Lefer Authors of One of the 10 Most Read Articles of 2011 in Circulation Research

January 2012

As recently reported by Circulation Research, "Exercise Protects Against Myocardial Ischemia-Reperfusion Injury via Stimulation of ß3-Adrenergic Receptors and Increased Nitric Oxide Signaling: Role of Nitrite and Nitrosothiols" was one the journal's ten most downloaded articles between January 2011-December 2011. The introduction to the listing states that the ten articles "represent paradigms of scientific excellence, particularly with respect to the three criteria that we value most: conceptual and/or mechanistic novelty, scientific impact, and methodological rigor."

Dr. David Lefer, director of the Emory Cardiothoracic Research Laboratory, Dr. John Calvert, also affiliated with the lab, and their co-authors presented new evidence that the heart's ability to store the nitric oxide generated during exercise appeared to be an essential component to protecting the heart after a heart attack.

The researchers found that voluntary exercise boosted endothelial nitric oxide synthase (eNOS, an enzyme that produces nitric oxide), and that the level stayed high for a week after exercise ceased unlike other heart enzymes stimulated by exercise. Nitric oxide turns on chemical pathways that relax blood vessels to increase blood flow and activate survival pathways. The study found that both the chemical nitrite and nitrosothiols, nitric oxide attached to proteins via sulfur, appear to act as convertible reservoirs for nitric oxide in critical situations such as a lack of blood flow or oxygen.

In experiments with mice, the researchers showed that four weeks of being able to run on a wheel protected the mice from having a blocked coronary artery; the amount of heart muscle damaged by the blockage was less after the exercise period. Importantly, the mice were still protected a week after the wheel was taken away. However, the study found that the protective effects of exercise did not extend beyond four weeks after exercise ended, when nitrite and nitrosothiols in the heart returned to baseline.