Getting to the heart of aging:

Dr. Susan Howlett explores the impact of aging on heart-cell function

What changes in the heart to make us more vulnerable to heart disease as we get older? Dr. Susan Howlett, a professor in Dalhousie’s Department of Pharmacology, wants to know – so the world-renowned heart researcher is investigating the impact of aging on heart function, and the impact of heart disease on aging hearts.

“First, we want to see how heart cells change their function in a healthy aging situation,” says Cardiovascular Research Group member Dr. Howlett, who has been studying heart cells for more than 20 years. “Then, we’ll expose heart cells to disease conditions to see if the older cells die, or change more rapidly or profoundly, than the younger cells.” She and her colleagues have developed an experimental model using isolated heart cells that creates, in effect, ‘heart attack in a dish.’ By lowering oxygen levels and increasing carbon dioxide, acidity, sugar, nitrogen and other factors, the model mimics what happens in a human heart during a heart attack.

Dr. Howlett aims to identify and measure specific changes to heart cell function in both healthy and unhealthy aging situations. “We’ll be looking for changes in such areas as contractile function, electrical activity, and rhythm,” she says, noting that these are the functions most often disrupted in heart failure. “If we can find specific mechanisms that make aging hearts more vulnerable to heart disease, they will lead us to targets for preventive therapy. But of course, the best preventive therapy of all is exercise and a healthy diet!”

Dr. Howlett has also discovered gender differences in heart-cell function. It seems that male heart cells show age-associated deficits, while cells from females of the same age do not. “It might be that females will eventually show deficits, but we do not know this for certain yet,” she says. “We are also pursuing this aspect of the work.”