Young at heart
Cardiovascular disease is the greatest killer of humans the world over, presenting huge financial and quality-of-life issues. It is well known that the heart becomes less efficient with age in all mammals studied to date, even in the absence of overt cardiac disease.
But scientists still don’t have a good understanding of how to prevent these functional declines.
The longest-lived rodent, the naked mole rat, beats these odds and escapes cardiovascular aging, at least in ages equivalent to 92-year-old humans, researchers from the School of Medicine reported.
Kelly Grimes, a graduate student in the Health Science Center’s Barshop Institute for Longevity and Aging Studies, has conducted the first studies of naked mole rat cardiovascular function. Her findings of maintained cardiovascular function during aging support earlier studies that this species resists the common signs of aging.
She found that, at rest, the heart of the naked mole rat beats very slowly at 250 beats per minute. The rodent should have a heart rate twice as fast for its body size. The blood pressure in naked mole rats is also very low, as is the amount of blood the heart pumps and how hard it contracts to pump the blood.
“However, if they need to, for example during exercise, naked mole rats can ramp up their cardiac function with ease,” Grimes said. “Their entire cardiovascular system seems to be optimized.”
These data are from two papers recently published by Grimes and Rochelle Buffenstein, Ph.D., as part of a study supported by the American Heart Association. Dr. Buffenstein emphasized that the naked mole rat is unlike any other cardiovascular aging model studied.
“It looks like the naked mole rat maintains heart function at youthful levels at least till age 90,” Dr. Buffenstein said. “Clearly these animals hold the secret to healthy hearts in aging humans.”
Why do humans, rats, mice, monkeys, dogs and other animals show declines, but not the naked mole rat? Grimes is studying molecular mechanisms that might be protecting the naked mole rats’ cardiovascular structure and function. These protective mechanisms are likely closely linked to their natural subterranean environment and exceptional stress resistance.
The two papers are in the American Journal of Physiology-Heart and Circulatory Physiology published by the American Physiological Society.