May 10, 2000
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PIGS HAVE IMPORTANT MESSAGE FOR HUMANS -- INACTIVITY CAN KILL YOU
NIH Renews Grant for $8 Million to Continue Study of Exercise
by Jason L. Jenkins
COLUMBIA, Mo. -- Pigs on treadmills? Although the idea might evoke comical images, it has proven to University of Missouri-Columbia researchers the importance of exercise in preventing heart disease. According to their research, exercise can help promote healthy heart function and fend off one of the nation's biggest killers, heart disease.
"In the United States, coronary heart disease remains the No. 1 cause of death for both men and women, and one of the primary risk factors for the disease is a sedentary, or inactive, lifestyle," said Harold Laughlin, principal investigator on the project and chair of the Department of Veterinary Biomedical Sciences. "Sixty percent of the adult population is inactive at a rate that doubles the chance of heart disease. We need to gain a better understanding of the cellular and molecular mechanisms responsible for exercise-induced changes, otherwise activity related diseases are going to get worse."
In 1995, an interdisciplinary team of researchers from the College of Veterinary Medicine's Department of Veterinary Biomedical Sciences, the School of Medicine's Department of Physiology and the Dalton Cardiovascular Research Center combined their efforts to study exercise's structural and functional impacts on the cardiovascular system using miniature Yucatan pigs. Since then, the researchers have discovered many different ways in which exercise benefits humans.
Laughlin himself has studied the benefits of exercise for almost 30 years. As a graduate student, he worked with Yucatan pigs because of the advantages they offer. "Because they are a miniature breed, they're easier to work with and don't require as much food or space," he said. "In addition, their coronary anatomy is very similar to humans, as is their sedentary nature, which makes them a sufficient model for study."
The National Institutes of Health-funded project has been a combination of many related projects that share a common goal, the prevention of heart disease. One project has focused on smooth muscle cells. These cells, which allow functions such as breathing, digestion and blood flow to occur involuntarily, are less likely to contract in large arteries of exercise subjects. Because coronary disease causes arteries to contract more often, exercise may help to offset effects of coronary disease.
A second project has focused on cells that line blood vessels, called endothelial cells. Laughlin said experts thought these cells only functioned as a lining for the blood vessels. However, research has shown that endothelial cells release chemical signals that prompt a number of responses, including blood vessel contraction. "We have found that exercise improves the ability of these cells to tell smooth muscle to relax, which could be beneficial in coronary heart disease," he said.
Other projects have studied the role intracellular calcium plays in contraction and the flow of nutrients from blood to heart tissue. As the project enters its second five-year funding period, Laughlin said ongoing projects will continue with their original objectives. "Because of the changes we have seen in smooth muscle and endothelial cells, we're interested in the molecular mechanisms that caused them," he said. "We're also going to continue to study the effects of exercise on pigs, this time on those that have been fed a high-fat diet."
As more is learned about the importance of exercise to cardiovascular health, Laughlin suggests that those looking to optimize their health follow the recommendations of the National Heart Association. "Since the Industrial Revolution, society has tried to make life easier, but we have gone too far," he said. "Our bodies are designed to be active, and we need to do more. Inactivity itself is a disease."
The original project was funded with a five-year, $6.8 million grant from the NIH. Following the results of the first study, the NIH renewed the grant for $8 million over the next five years.
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