Hypoxia training suppresses harmful cardiac nitric oxide production during heart attack

May 23, 2008

Researchers at the University of North Texas Health Science Center, Fort Worth, Texas have demonstrated that, contrary to prevailing dogma, hypoxia can be remarkably beneficial to the heart. These discoveries, to be reported in the June 2008 issue of Experimental Biology and Medicine, may lead to a new paradigm to protect hearts of patients at risk of coronary disease. Hypoxia is generally considered harmful to the heart, since a steady supply of oxygen is required to maintain cardiac function. However, this research has demonstrated that a 20 day program of brief, repetitive, moderate reductions in the amount of oxygen in the arterial blood induce adaptations which increase the heart's resistance to the more severe insult of a heart attack. In particular, intermittent hypoxic treatment of dogs remarkably reduced myocardial infarction and lethal arrhythmias following coronary artery occlusion and reperfusion.

The research team, led by Robert T. Mallet, Associate Professor of Integrative Physiology, H. Fred Downey, Regents Professor of Integrative Physiology, and doctoral student Myoung-Gwi Ryou explored mechanisms that may be responsible for this remarkable cardioprotection. Specifically, the investigators tested the hypothesis that intermittent hypoxia treatment suppressed harmful over-production of nitric oxide, the precursor of a host of toxic compounds, by heart tissue upon coronary artery reperfusion. One day after completing 20 days of intermittent hypoxia treatment, dogs were anesthetized and a coronary artery was surgically obstructed for 60 minutes, and then the obstruction was removed and artery was reperfused. An explosive burst of cardiac nitric oxide production occurred during the first few minutes of reperfusion in untreated dogs, but this harmful burst was considerably dampened in hypoxia-treated dogs, without compromising recovery of coronary blood flow. Hypoxia treatment also suppressed cardiac activity of nitric oxide synthase (NOS), the enzyme that produces nitric oxide, as well as the heart's content of the principal NOS isoform, endothelial NOS.

According to Dr. Mallet, "reduced NOS activity may contribute to the cardiac benefits of hypoxia treatment by decreasing formation of a free radical, superoxide, as well as nitric oxide. Both of these compounds are produced by NOS. When these two compounds are produced simultaneously, they combine to form peroxynitrite, an extremely aggressive chemical by-product that injures the heart by damaging the molecular components of cells. By decreasing NOS activity in the heart, hypoxia treatment could minimize formation of peroxynitrite and other harmful products of nitric oxide and superoxide."

"Intermittent hypoxia treatment may be a powerful adjunctive therapy for patients at risk of heart disease" says Dr. Downey. "The brief periods of moderate hypoxia are easily tolerated by most people, require neither surgery nor expensive medications, and can be administered by the patient at home or work using available devices. Indeed, intermittent hypoxia has been used for several decades in Eastern Europe to treat heart and neurological diseases and high blood pressure." Dr. Steven R. Goodman, Editor-in-Chief of Experimental Biology and Medicine stated "This study by Robert Mallet and colleagues may suggest a simple treatment to minimize the impact of a heart attack and should stimulate further study of this phenomena".
-end-
Experimental Biology and Medicine is the journal of the Society of Experimental Biology and Medicine. To learn about the benefits of society membership visit www.sebm.org. If you are interested in publishing in the journal please visit www.ebmonline.org.

Society for Experimental Biology and Medicine

Related Heart Disease Articles from Brightsurf:

Cellular pathway of genetic heart disease similar to neurodegenerative disease
Research on a genetic heart disease has uncovered a new and unexpected mechanism for heart failure.

Mechanism linking gum disease to heart disease, other inflammatory conditions discovered
The link between periodontal (gum) disease and other inflammatory conditions such as heart disease and diabetes has long been established, but the mechanism behind that association has, until now, remained a mystery.

New 'atlas' of human heart cells first step toward precision treatments for heart disease
Scientists have for the first time documented all of the different cell types and genes expressed in the healthy human heart, in research published in the journal Nature.

With a heavy heart: How men and women develop heart disease differently
A new study by researchers from McGill University has uncovered that minerals causing aortic heart valve blockage in men and women are different, a discovery that could change how heart disease is diagnosed and treated.

Heart-healthy diets are naturally low in dietary cholesterol and can help to reduce the risk of heart disease and stroke
Eating a heart-healthy dietary pattern rich in vegetables, fruits, whole grains, low-fat dairy products, poultry, fish, legumes, vegetable oils and nuts, which is also limits salt, red and processed meats, refined-carbohydrates and added sugars, is relatively low in dietary cholesterol and supports healthy levels of artery-clogging LDL cholesterol.

Pacemakers can improve heart function in patients with chemotherapy-induced heart disease
Research has shown that treating chemotherapy-induced cardiomyopathy with commercially available cardiac resynchronization therapy (CRT) delivered through a surgically implanted defibrillator or pacemaker can significantly improve patient outcomes.

Arsenic in drinking water may change heart structure raising risk of heart disease
Drinking water that is contaminated with arsenic may lead to thickening of the heart's main pumping chamber in young adults, according to a new study by researchers at Columbia University Mailman School of Public Health.

New health calculator can help predict heart disease risk, estimate heart age
A new online health calculator can help people determine their risk of heart disease, as well as their heart age, accounting for sociodemographic factors such as ethnicity, sense of belonging and education, as well as health status and lifestyle behaviors.

Wide variation in rate of death between VA hospitals for patients with heart disease, heart failure
Death rates for veterans with ischemic heart disease and chronic heart failure varied widely across the Veterans Affairs (VA) health care system from 2010 to 2014, which could suggest differences in the quality of cardiovascular health care provided by VA medical centers.

Heart failure: The Alzheimer's disease of the heart?
Similar to how protein clumps build up in the brain in people with some neurodegenerative diseases such as Alzheimer's and Parkinson's diseases, protein clumps appear to accumulate in the diseased hearts of mice and people with heart failure, according to a team led by Johns Hopkins University researchers.

Read More: Heart Disease News and Heart Disease Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.