One Drink Of Red Wine Or Alcohol Is Relaxing To Circulation, But Two Drinks Are Stressful

Daily Science Journal (Feb. 13, 2008) — One drink of either red wine or alcohol slightly benefits the heart and blood vessels, but the positive effects on specific biological markers disappear with two drinks, say researchers at the Peter Munk Cardiac Centre of the Toronto General Hospital.

Researchers conducted a real-time study of thirteen volunteers to determine whether a red wine with a verified high polyphenol content differs from alcohol in its effects on specific markers associated with a greater risk of high blood pressure, coronary artery disease and heart failure.

A large number of population studies have shown a protective effect of light or moderate alcohol drinking against the risk of death and the development of heart disease. Many studies have also reported specific benefits of red wine.

Population surveys found lower rates of heart disease, despite high-fat diets, in some European countries where red wine was consumed regularly. Widely known at the French paradox, this has created a huge interest in exploring if and how red wine has a protective effect against heart disease.

However, the findings of this study* showed virtually identical effects of red wine and alcohol on the specific markers tested. After one drink of either red wine or alcohol, blood vessels were more “relaxed” or dilated, which reduced the amount of work the heart had to do. But, after two drinks, the heart rate, amount of blood pumped out of the heart, and action of the sympathetic nervous system all increased. At the same time, the ability of the blood vessels to expand in response to an increase in blood flow diminished. This counteracted the beneficial effect of one drink of red wine or alcohol.

“We had anticipated that many of the effects of one ethanol drink would be enhanced by red wine. What was most surprising was how similar the effects were of red wine and ethanol. Any benefits that we found were not specific to red wine,” said Dr. John Floras, Director of Cardiology Research at the Peter Munk Cardiac Centre, and at Mount Sinai Hospital, in whose laboratory the study was performed. However, Dr. Floras cautioned this study measured the effects of these drinks on one occasion only. The effects of daily wine or alcohol intake may be quite different.

The laboratory of Dr. Floras, who holds the Canada Research Chair in Integrative Cardiovascular Biology and is a Professor of Medicine at the University of Toronto, and a Career Investigator of the Heart and Stroke Foundation, is one of the few in the world equipped to measure simultaneously a broad spectrum of factors such as blood pressure, heart rate, sympathetic nerve firing and arterial diameter.

Healthy, non-smoking adults who were not heavy drinkers or total alcohol abstainers were studied. Participants attended three separate morning sessions during which “standard” drinks of red wine, ethanol or water were administered at random, single-blind, two weeks apart. A 4-oz glass of wine (120 ml), and a 1.5-oz (44 ml) shot of spirits is considered to be one standard drink. All blood alcohol levels alcoholic were below .08, the legal limit for drivers.

The Quality Assurance Laboratory of the Liquor Control Board of Ontario selected a moderately priced pinot noir with a verified high t-resveratrol content, a polyphenol compound found in plants, including red grapes, which exhibits antioxidant properties. Alcohol or substances in alcohol such as resveratrol may improve blood vessel function and also prevent platelets in the blood from sticking together, which may reduce clot formation and the risk of heart attack or stroke.

Select study findings:

One drink of either red wine or alcohol:

* Has no effect on heart rate, blood pressure or sympathetic nerve activity, which activates the “fight or flight” reaction and generally modulates heart rate and sets the diameter of blood vessels in order to redistribute blood;
* Dilates the brachial artery.

Two drinks of either alcohol or red wine:

* Increase sympathetic nerve activity, heart rate, and the amount of blood the heart pumps out, and also blunt the ability of the brachial artery to expand further in response to blood flow.
* Increases in heart rate and sympathetic nerve activity are recognized markers for hypertension (high blood pressure), heart failure and sudden death.

“Our findings point to a slight beneficial effect of one drink – be it alcohol or red wine – on the heart and blood vessels, whereas two or more drinks would seem to turn on systems that stress the circulation. If these actions are repeated frequently because of high alcohol consumption these effects may expose individuals to a higher risk of heart attacks, stroke or chronic high blood pressure,” noted Dr. Floras, adding that the American Heart Association (AHA) does not recommend that anyone start drinking alcohol to prevent heart disease. Reducing risk can be done using other methods such as exercise and following a healthy diet.

The study entitled “Dose-related effects of red wine and alcohol on hemodynamics, sympathetic nerve activity, and arterial diameter”, was published in the February edition of the American Journal of Physiology, Heart and Circulatory Physiology. This study was supported by the Heart and Stroke Foundation of Ontario, the Canadian Institutes of Health Research, and the Canada Research Chairs Program.

Adapted from materials provided by University Health Network, via Newswise.

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Diabetes Makes It Hard For Blood Vessels To Relax

Daily Science Journal (Feb. 1, 2008) — One way diabetes is bad for your blood vessels is by creating too much competition for an amino acid that helps blood vessels relax, researchers say.

One way diabetes is bad for your blood vessels is by creating too much competition for an amino acid that helps blood vessels relax, researchers say. (Credit: Image courtesy of Medical College of Georgia)

That amino acid, L-arginine, is broken down by the enzyme arginase to urea, which helps the body eliminate toxins resulting from the proteins we eat. Diabetics have a lot of arginase activity, which means they use a lot more L-arginine, says Dr. Maritza Romero, postdoctoral fellow at the Medical College of Georgia and lead author of the paper published in the current issue of Circulation Research.

It also means too little L-arginine is available to help nitric oxide synthase make nitric oxide, the powerful vasodilator that helps blood vessels relax, says Dr. Romero, who works in the lab of Dr. R. William Caldwell, chair of the MCG Department of Pharmacology and Toxicology and the study's corresponding author.

Researchers also found the amino acid, L-citrulline, as well as statins, compounds known to lower cholesterol, prevent elevation of arginase activity, restoring normal dilation abilities in animal models of type 1 diabetes. In fact, L-citrulline can be recycled into L-arginine.

Now they want to know specific factors and pathways involved in arginase activation and develop pharmaceutical agents to combat excessive arginase activity in diabetes. They also suggest clinical trials of L-citrulline as a supplemental therapy for diabetics with vascular problems.

Their findings also help explain why L-arginine supplement, marketed to treat hypertension, chest pain, heart failure and more, may not work long term. In the January 4, 2006 issue of the Journal of the American Medical Association, Johns Hopkins researchers reported that a clinical trial of patients taking an L-arginine supplement following a heart attack didn't improve in their vascular tone or their hearts' ability to pump. In fact, more patients died who were taking L-arginine than placebo and the study was closed with the recommendation the supplement not be used by heart attack patients. The supplement still is widely marketed.

"The findings of increased arginase I activity in diabetes may limit other therapeutic approaches proposed for early endothelial dysfunction such as oral L-arginine supplementation," Drs. Thomas L. Luscher and Jan Steffel, of the University of Zurich Cardiovascular Research Institute write in an accompanying editorial. "Although dietary L-arginine supplementation has been shown to exert vascular protective effects in certain clinical settings, this approach is unlikely to be effective in diabetes, if the results of this study can be confirmed by patients in vivo. In fact, the findings of Romera et al may provide a possible explanation for the unexpected neutral or even adverse effects of oral L-arginine in some clinical studies, in particular patients with coronary artery disease and infarction."

A short intravenous course of L-arginine may provide short-term improvement in blood vessel tone, Dr. Romero notes. However most of L-arginine ingested goes directly to the liver to be broken down, not the bloodstream where it can promote relaxation of blood vessels, Dr. Romero says.

Arginase also is associated with vascular problems related to aging, hypertension, sickle cell disease, atherosclerosis and erectile dysfunction, Dr. Romero says. L-citrulline already is taken by some sickle cell patients to reduce breath-taking fibrosis in their lungs. In addition to helping the body turn toxins into urea that can be safely eliminated from the body, arginase also helps in collagen formation and cell proliferation, but too much can be bad. In fact, Drs. Caldwell and Romero are pursuing studies of how increased arginase activity may harden blood vessel walls.

Adapted from materials provided by Medical College of Georgia.

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