IEven if a person eats 50% of their body weight at one time, their body may not be able to accept it. Their stomachs swell and their hearts begin pumping blood furiously to maintain the metabolism needed to digest such a meal. But this happens to pythons many times, and in the wild Burmese and ball pythons rarely encounter food and can go up to two years without eating. Therefore, they eat as much as they can when they get the chance, sometimes consuming half their body weight.
Researchers are currently studying the python’s organs, especially heartdeal with such stress.1 In a new study published in Proceedings of the National Academy of Sciences, The researchers showed that the heart muscle fibers of fed pythons were less stiff, while still producing more force than those of starved pythons. Many heart diseases are characterized by heart stiffness, so understanding this extreme adaptation could provide insight into heart health in other animals, including humans.
“[The study] This provides some of the first molecular insights into how the heart functions under very long and intense demands such as digestion. ” tobias wanHe is an animal physiologist at Aarhus University but was not involved in the study.
leslie rainwanda molecular biologist at the University of Colorado Boulder and co-author of the study, first started looking at how pythons live. adapted Back in 2011 to deal with these huge feeds.2 She and her team discovered the heart of a Burmese python. swollen After breastfeeding.3
“We wanted to better understand these heart changes because no other mammal does anything close to what these pythons do,” Reinwand said.
So Reinwand’s team acquired ball pythons and studied cardiac output, or how much blood the heart can pump. Cardiac output increases after feeding to maintain metabolic activity. Specifically, the research team studied heart muscle activity in two groups of ball pythons. One group was fasted for 28 days, and the other group was fed a large meal containing 25 percent of the rats’ body weight 24 hours before the experiment.
The researchers found that the hearts of fed pythons increased by about a quarter compared to those of starved pythons. Using a rheometer that applies force to the sample, the researchers found that the heart tissue of fed pythons was less stiff than that of unfed pythons.
The researchers then isolated the heart muscle cells (cardiomyocytes) and the fibers within the cells (myofibrils) and looked at how these adapted after being fed large amounts of food, comparing them to those of a starving python. compared. Cardiomyocytes from fed pythons appeared to have longer-lasting calcium currents, an important aspect of heart function. The team then attached the myofibrils to the rig, and by moving them between a calcium-free solution and a solution containing high concentrations of calcium, which activates the muscle fibers, the myofibrils were stimulated, measured by force sensors. We measured how much force it generated. They found that fed pythons produced more force. By improving the effectiveness of contractile proteins in the heart, pythons have a way to increase the amount of blood pumped out, Wang said.
“For an animal to change the nature of its heart within 24 hours is astonishing both in its magnitude and in its speed,” Reinwand said. To find out exactly how quickly this is happening, the research team looked for signs that indicate how accessible genes are to translation. For example, the researchers showed that compared to fasted pythons, fed pythons had higher activity in enzymes involved in regulating accessibility, which may open up chromatin to allow translation. I have confirmed that it is. The research team stained the nuclei of muscle cells and calculated a parameter called chromatin condensation. In fact, chromatin was more condensed in starved pythons than in fed animals.
Next, they looked at changes in gene expression during feeding that might be driving these effects. RNA sequencing of fed and unfed pythons revealed that feeding increased genes involved in endoplasmic reticulum processes and proteins. Reinwand says this suggests that the body has ramped up protein production to make the organ, in this case the heart, bigger.
Wang hopes future studies will investigate epigenetic changes and the drivers of changes in gene expression. “Is it some kind of factor circulating in the plasma, or does it occur as a result of mechanical stress on the heart?” he wondered. “Such experiments would be very interesting.”
Understanding how pythons rapidly remodel their hearts to become bigger and stronger after eating large meals could offer new ways to make stiff, diseased human hearts more flexible and functional. , Reinwand said. Wang agreed, saying that the python’s extreme physiological adaptations provide a unique biological model, although it is years away from real-world applications. “If it were to be used and seen as something that could manipulate human disease, snakes would have been an inspiration,” he says.
