Animal Models

Another important aspect of the research done by the SPH team is that they "study only non-painful types of stress," Kirby said. "This is because people who are under stress are usually frustrated, not in pain. We try to model this as best as we can in animals."

The experimenters do this by putting a group of pigs under non-painful stress--by such techniques as lifting their feet several inches off the ground--and comparing the levels of norepinephrine in these pigs to the levels of the hormone in a control group of non-stressed pigs.

The pigs were chosen because their hearts "are similar to those of humans," Kirby said. Models of the pigs' physiological response to stress have shown that the animals under stress have higher levels of norepinephrine than their counterparts in control groups. The pigs subjected to stress even develop ventricular fibrillation.

"We think this shows that stress can make arrythmia easier to induce," Kirby said.

One of the goals of the study, Kirby said, is to find ways to "predict why only some people develop fatal heart rhythms under stress." Such an understanding will not only help prevent sudden stress-caused deaths but will facilitate the discovery of drugs to aid the heart in times of frustration, she said.

The research is funded by the Lown Cardiovascular Research Foundation, a non-profit private organization founded by Bernard Lown, professor of cardiology in nutrition at the SPH, said Arlene Fortunato, director of the foundation.