The following story by Jeff Hansen, of The Birmingham News is being carried by AL.com. At left, University of Alabama biologist Stephen Secor holds a Burmese python.
University of Alabama biologist Stephen Secor fell in love with snakes in college.
He then spent his graduate years chasing coachwhip snakes and venomous sidewinders across the Mojave Desert, learning what and when they ate. And for the past 15 years, Secor has studied the Burmese python -- a docile ambush-feeder that may eat only every other month or even just once a year in the wild.
The Burmese python, it turns out, is a prime model for intense physiological changes after breaking its long fast, as Secor detailed in a 1998 Nature cover story. Within 48 to 72 hours after swallowing its prey, pythons show intense increases in metabolism -- up to 44-fold -- and rapid growth of organs, including a 40 percent increase in its heart size.
That change in heart size is the focus of recent research at the universities of Alabama and Colorado -- and payoff from the research may lead toward treatment for human congestive heart failure.
In 2006, Secor was contacted by cardiac biologist Leslie Leinwand of the University of Colorado. She wanted to discover what molecular mechanism caused the cells of the python's heart to increase in size so rapidly, and see if that same trigger had an effect in mammals.
One early experiment in their collaboration was simple but startling, and showed that there seemed to be some factor in the blood of the python that made the heart suddenly increase in size.
In the experiment, done by co-author and post-doctoral student Cecilia Riquelme at Colorado, blood plasma from a just-fed python was added to a culture of rat heart muscle cells. The plasma caused a significant increase in the size of the rat muscle cells.
"When they found that, they said, 'Ooo, we've got something,'" Secor said. The hunt for the underlying cause of this increased cell size began.
Findings
In a paper published in Science in October, the researchers found that:
The blood plasma of a just-fed python had a superabundance of fatty acids.
That plasma, when fed to a fasting Burmese python, made its heart grow in size, similar to eating a meal.
A mixture of three of those fatty acids given to pythons intravenously duplicated this heart growth.
That same mixture of fatty acids, given to living mice, significantly increased the size of their left ventricles -- the major pumping chamber of the heart -- and the size of their heart muscle cells.
Leinwand is pursuing possible application of this discovery to human heart disease.
"I think congestive heart failure would be the first and most prevalent thing to consider," she said. "It's important that people distinguish between congestive heart failure, which is chronic and debilitating, from a heart attack, which is very different and acute."
About 5 million people in the United States have heart failure, according to the National Institutes of Health, and it contributes to about 300,000 deaths each year.
Secor, meanwhile, has returned his focus to changes in the digestive system of the Burmese python as it begins or ends its meal.
"Hearts are OK," he said, "but it's nothing like the intestine."
The stomach of the Burmese python, for example, stops producing acid within minutes of the snake clearing its stomach. The intestines reduce their size, and their hair-like microvilli shorten dramatically.
"The Burmese python does all sorts of interesting things," Secor said.
The snakes that Secor uses in research studies are usually "no longer than this table," he said, pointing at his desk. Each weighs about one or two pounds.
Secor has done hundreds of snake surgeries over the years. In the experiments to give blood plasma of fed snakes to snakes that have been fasting, for example, he had to place a thin catheter into the liver vein of the snake.
His office shows his roots in general biology.
On the wall he has the 13-foot skin from his former family pet, a Burmese python named Linus. He also has long rows of animal skulls he uses in some of his biology classes. In cages next door he keeps some of the pythons and other animals that he takes during visits to schools.
"I do biology," Secor said, "for the love of biology."
