The researchers believe their study provides evidence that the natural tendency of the body is to adapt to oxidative stress during healthy aging.
Oxidative stress damages cells by attacking DNA, proteins and lipids. It arises from an imbalance between generation of reactive oxygen species (ROS) and their removal by antioxidants.
In a study published in The Journal of Physiology, researchers at the University of Missouri School of Medicine in Columbia, describe how tests on mice reveal aging actually appears to offer significant protection against oxidative stress.
They say their findings suggest healthy aging triggers an adaptive response that counteracts the effect of oxidative stress on blood vessels.
Senior author Steven Segal, a professor of medical pharmacology and physiology, explains that while ROS are important for controlling cell function, if levels get too high they lead to oxidative stress which can lead to problems with cell growth and reproduction.
Oxidative stress led to abnormally high calcium in blood vessels of younger mice
To examine how aging affects blood vessels exposed to oxidative stress, the researchers studied the endothelium or inner lining of small, resistance arteries in mice. These blood vessels regulate the amount of blood that enters tissue and control systemic blood pressure.
The team used male mice aged 4 months and 24 months, equivalent to the early 20s and mid-60s in human years.
First they studied the endothelium at rest, in the absence of oxidative stress. Then they simulated oxidative stress by adding hydrogen peroxide.
The results showed that 20 minutes of oxidative stress resulted in abnormally high levels of calcium in the endothelium cells of the younger mice compared to the older mice.
"This finding is important," Prof. Segal says, "because when calcium gets too high, cells can be severely damaged."
Further tests showed that 60 minutes of oxidative stress led to a seven-fold increase in cell death in the endothelium of the younger mice compared to the older mice.
The researchers suggest the findings show that with age, the endothelium adapts to protect cells against abrupt increases in oxidative stress, ensuring that the arteries of older individuals can still function.
Prof. Segal says they were most surprised when they found the endothelium of the older mice appeared to be much less perturbed by oxidative stress. He concludes:
"This finding contrasts with the generally held belief that the functional integrity of the endothelium is compromised as we age.
Although more studies are needed to identify the mechanism by which the endothelium adapts to advanced age, our study provides evidence that the natural tendency of the body is to adapt to oxidative stress during healthy aging."
Earlier this year, Medical News Today learned about a new biodegradable material for making artificial blood vessels that appears to be more compatible with body tissue than those currently used. The team that is developing it - from Vienna University of Technology and Vienna Medical University - has successfully tested it in rats, and believes it will lead to greater use of artificial blood vessels in human patients.