Mammals and cold-hearted alligators share a common four-chambered heart structure with unique reptiles, but this is where the similarities end. Unlike humans and other mammals, whose hearts can vibrate during stress, alligators have built-in antiarrhythmic protection. The results of the new study were reported on January 27, 2021 in the journal Integrative Organic biology,
“Alligator hearts do not give up, no matter what we do. “They are very resilient,” said Flavio Fenton, a professor at the School of Physics at the Institute of Technology and a researcher at the Petit Institute of Biotechnology and Biology. Fibrillation is one of the most dangerous arrhythmias, which leads to a stroke of blood tissue when it occurs in the atrium, and dies within a few minutes when it occurs in the ventricles.
The study looked at the potential wavelengths of rabbit և young alligator hearts. Both species have four chamber hearts of similar size (about 3 cm); however, while rabbits maintain a stable heart temperature of 38 degrees Celsius, the body temperature of active, wild alligators ranges from 10 to 37 degrees Celsius. The heart pump is controlled by an electrical wave that tells the muscle cells to contract. The electrical signal drives this wave, which must occur in the same vein to maintain normal blood pumping. In a deadly arrhythmia, this electrical signal is no longer in tune!
“Arrhythmias can occur for many reasons, including a drop in temperature. “For example, if someone falls into the cold water and gets hypothermia, that person often has an arrhythmia and then drowns,” Fenton said.
During the study, the researchers recorded heart wave patterns at temperatures of 38 C և 23 C. “The agar’s heart rate wave decreased by more than half during temperature extremes, while the alligator’s heart showed a maximum change of about 10%,” said Conner Herndon, co-author of the Graduate School of Physics. “We found that when the spatial wavelength reaches the size of the heart, the rabbit may undergo spontaneous fibrillation, but the alligator will always maintain this wavelength in safe mode,” he added.
Although alligators can operate at high temperatures without the risk of heart injury, their built-in protection has one drawback. It limits their maximum heart rate, which allows them to expend extra energy in emergencies. Rab agars և other warm-blooded mammals may harbor higher heart rates required to maintain active, endothermic metabolism, but are at risk for cardiac arrhythmias և possible vulnerability to temperature changes.
Georgia Tech physicists collaborated on the study with two biologists, including Henry Estley, a former Georgia Tech postdoctoral fellow and now an associate professor at the Center for Biochemical Research and Innovation at Akron University.
“I was a little surprised how big the difference is. The transparency of the crocodile heart and the fragility of the rabbit heart. “I did not expect the rabbit’s heart to split like a jar like a seam,” said Estley.
Low temperatures are one of the causes of electrophysiological arrhythmias of the heart, when rapidly circulating electrical waves can cause the heart to beat rapidly, leading to cardiac arrest and sudden cardiac death. Lowering body temperature, which is often done for patients before certain surgeries, can also cause arrhythmias.
The researchers agree that this study may help to better understand how the heart works – what can cause a fatal arrhythmia, which is what happens when the heart no longer pumps blood properly.
The authors also consider the study to be a promising step towards a better understanding of cardiac electrophysiology and how to reduce the risk of fibrillation. By December 2020, when Covid-19 topped the list, heart disease was the leading cause of death in the United States, in many industrialized countries, where more people were dying from heart disease than the next two causes of death combined.
Astlyn said the study provides a deeper insight into the natural world, the various mechanisms by which cold, warm-blooded animals cope.
Tomas Overkovic, an associate professor at the Department of Biology at San Bernardino State University in California, says the results are “another piece of the puzzle that helps us understand how much non-human animals really are, how many different tricks they have.”
He hoped that more researchers would follow suit and use a non-traditional animal model in future research.
“Everyone studies mammals, fruit flies and zebras. There is so much wealth of resources among wildlife that has not been brought to the laboratory, where there are neat physiologies waiting to be discovered. “All we have to do is look,” he said.
Reference. “To you later defibrillation, alligator; Q10 scale և fire resistance keeps alligators back from fibrillation ”by C Herndon, HC Astley, T Owerkowicz և FH Fenton, January 27, 2021 Integrative organism biology,
DOI: 10.1093 / iob / obaa047: