A molecule in red blood cells protects against heart attack
Researchers at Karolinska Institutet have discovered that nitric oxide can be released from red blood cells and protects against myocardial infarction. In an article published in the scientific journal PNAS they describe a new function of red blood cells that has potential significance as a novel treatment of the disease.
Nitric oxide (NO) is formed in the vascular wall, and mediates an important function by increasing the flow of blood in the organs, including the heart by dilating the coronary arteries. Results from earlier research indicates that red blood cells can also bind and deliver NO, but as yet the effect of this has been unclear since the main function of red blood cells is to deliver oxygen to all cells of the body.
In the present study, the researchers found that red blood cells from humans, rats and mice are able to release NO through the regulation of an enzyme called arginase. Tests on mice showed that the damage caused by myocardial infarction (heart attack) decreased significantly when arginase was blocked in the red blood cells. This protective effect was produced by NO that was formed in and released from red blood cells.
"Our results indicate a hitherto unknown function of red blood cells, namely the ability to produce and release NO following arginase blockade, a finding that increases our understanding of the cause of myocardial infarction and how it can be treated." says Professor John Pernow who headed the study.
Cardiovascular disease is the most common cause of death amongst men and women in Sweden. Every year, some 30,000 people in Sweden suffer a myocardial infarction. The study was conducted with grants from the Swedish Research Council, the Swedish Heart & Lung Foundation, Karolinska Institutet/Stockholm County Council's Theme Centre for Cardiovascular Disease, the Stockholm County Council's ALF project fund, the Novo Nordisk Foundation, the Torsten Söderberg Foundation, and King Gustav V and Queen Victoria's Foundation.
Arginase regulates red blood cell nitric oxide synthase and export of cardioprotective nitric oxide bioactivity.
Proc. Natl. Acad. Sci. U.S.A. 2013 Sep;110(37):15049-54