MORGANTOWN, W.V. - When the circulation systems of young female rats behave differently than male and older rats' systems, it can make a researcher's day. "We had no idea that this was going to happen," Timothy R. Nurkiewicz, assistant professor at the West Virginia University School of Medicine, said of recent findings from his laboratory that have drawn a lot of attention. The research showed that diesel exhaust can compromise the arteries' abilities to regulate blood flow and that some people are more at risk than others. The findings help a little to clarify the still unclear science of cardiovascular dysfunction, according to Nurkiewicz. Air Pollution and the Heart Nurkiewicz described the problem at the center of his research. "Epidemiologists have identified over the past decade or so that on days when there are air pollution incidents, people are dying not of lung disease but of heart disease," he explained. "It flies counter to what we've been told for decades." As a microvascular specialist who studies the tiny blood vessels that deliver oxygen to the cells, Nurkiewicz works at the interface between the lungs and the circulation system -- the place where air pollution can cross into the body and affect the heart.
"We can breathe in larger particles without damaging the cardiovascular system," he explained -- they're filtered out in the nose or upper respiratory tract.
"But smaller particles, like ultra-fine particle matter and nanoparticles, penetrate deep into our lungs, where oxygen exchange occurs," he said.
Federal clean-air regulators classify air pollution particles in three sizes, Nurkiewicz said: coarse, up to 10 microns in diameter, about one-tenth the size of a human hair; fine, up to 2.5 microns; and ultra-fine, up to 0.1 micron.
"It's that ultra-fine fraction that has the ability to get across the membrane of the lung," he said. "They can leave the lungs and enter the body proper."
Two Heads Are Better
It was during a conversation over coffee one day, Nurkiewicz said, that he got into the topic with Judy Muller-Delp, a colleague at the WVU Center for Interdisciplinary Research in Cardiovascular Sciences who studies microcirculation with particular attention to gender and aging.
Nurkiewicz and Muller-Delp decided to conduct an experiment that would combine their interests, he said.
The two researchers, with colleague Rhonda D. Prisby, exposed the arteries of reproductive and post-reproductive male and female rats to a toxic component of diesel exhaust known as phenanthrenequinone, or PQ.
Then they measured the arteries' ability to dilate, or widen. "In the young males, the ability to dilate was impaired," Nurkiewicz said. "Then when you look in the older groups ... the ability is abolished." This finding has "ominous overtones" for what goes on in the human body, he said, with implications for heart health, as well as for immune function. But beyond that, in the younger female group, "the toxins had no effect," he added. "I thought the PQ would knock everything out across the board, so when the young females were resistant, I kind of initiated a lot of extra experiments to make sure what we were seeing was in fact true," he said. "It was a pleasant surprise." This result points to protective effects of estrogen against environmental pollutants, an American Physiological Society press release said when Nurkiewicz presented at the organization's annual meeting on May 1. "I've been involved in meetings now for 10 years, and not once has our work generated this much attention," he said of his APS presentation. "It's not novel that this toxin, this hydrocarbon that we studied, is bad. What is novel is that nobody's ever identified this level of vascular dysfunction with it," he said. With more research, the finding could lead to more effective air pollution regulations, he said. Source: The State Journal. Provided by ProQuest Information and Learning. Powered by Yellowbrix.
