Getting older may offer blood vessels protection from oxidative stress, which is thought to play a critical role in several diseases, including hypertension and cancer.
“Molecules known as reactive oxygen species, or ROS, play an important role in regulating cellular function,” says Steven Segal, a professor of medical pharmacology and physiology at the University of Missouri School of Medicine and senior author of the study. “However, the overproduction of ROS can help create a condition referred to as oxidative stress, which can alter the function of cells and interfere with their growth and reproduction.”
To understand the effects of aging on the function of blood vessels when they are exposed to oxidative stress, Segal’s team studied the inner lining, or endothelium, of small resistance arteries. Resistance arteries are important to cardiovascular function because they regulate both the amount of blood flow into tissues and systemic blood pressure.
“We studied the endothelium from resistance arteries of male mice at 4 months and 24 months of age, which correspond to humans in their early 20s and mid-60s,” Segal says. “We first studied the endothelium under resting conditions and in the absence of oxidative stress.
“We then simulated oxidative stress by adding hydrogen peroxide. When oxidative stress was induced for 20 minutes, the endothelial cells of the younger mice had abnormal increases in calcium when compared to the endothelial cells of the older mice. This finding is important because when calcium gets too high, cells can be severely damaged.”
When oxidative stress was extended to 60 minutes, Segal’s team found that the death of endothelial cells in the younger mice was seven times greater than those from the older mice.
“The most surprising thing we found is that the endothelium was much less perturbed by oxidative stress during advanced age when compared to younger age,” Segal says. “This finding contrasts with the generally held belief that the functional integrity of the endothelium is compromised as we age.
“Our study suggests that blood vessels adapt during the aging process to regulate ROS and minimize cell death when subjected to an abrupt increase in oxidative stress. This adaptation helps to ensure that the arteries of older individuals can still do their jobs.”
The study, funded by the National Institutes of Health, appears in the Journal of Physiology.