Ask any runner what they eat before a long race, and you’ll likely get a variety of answers. Some suggest a light meal of fruit or lean protein an hour before the race, while others advise. Prepare the pasta the night before. But for vampire bats, it turns out that a bowl of amino acid-rich blood is sufficient.
Researchers at the University of Toronto captured several vampire bats and taught them to run on a treadmill. By analyzing the bats’ breath, the researchers found that the bats primarily use amino acids from their recent blood meals as their primary energy source for running. Those discoveries are published this week biology letterssuggesting that vampire bats may have evolved to develop a unique metabolism typically observed in blood-sucking insects.
No problem without carbohydrates
Bats are unique among mammals, and vampires are unique among bats. This creature, which inspired horror novels, lives solely on the blood of its victims. Vampire bats typically fly close to their prey and then use their thumbs and wrists to quickly walk or run to get closer. It then latches on to its target, a peccary or capybara, and uses its teeth to make a small incision and draw blood. If necessary, vampire bats can guzzle four times their body weight in liquid.
However, relying solely on blood severely limits what vampires can use for energy. Most mammals, including humans, promote exercise by burning carbohydrates and fats that are not normally present or present in the blood. Blood is rich in amino acids, which make up proteins, but they typically only account for about 10% of the fuel mammals use during exercise. Through generations of evolution, vampire bats have managed to flip that script and maintain themselves. mainly Turn off amino acids. not enough bats Genes required for insulin secretion Therefore, they have no choice but to make do with what is available.
“Amino acids are the fuel of last resort in most animals,” says study co-author Ken Welch, a professor at the University of Toronto’s Scarborough College. stated in a statement. “This is what the body burns off when there’s very little left, and this bat burns it off quickly.”
Researchers trained rats to jog on a treadmill
To scientifically measure this observation, the researchers captured 20 vampire bats from Belize and trained them to use a small treadmill typically used to measure metabolic rates in rats. The goal of the experiment was to first feed the bats cow blood, which is rich in two types of isotopically labeled amino acids, and then measure their breathing while running. The researchers sourced blood from a local slaughterhouse and gave it to the bats using a pipette. It took some time, but the researchers were eventually able to train the bats to stop jumping off the side of the treadmill, walk and run at a steady pace. Some bats could run at speeds of 100 feet per second and maintain that speed for more than 90 minutes.
When researchers measured the carbon dioxide exhaled by bats, they found trace amounts of the same amino acids found in blood feasts. The breakdown of two additional amino acids in the blood, glycine and leucine, is thought to be responsible for up to 60% of the bat’s total energy production during running. Ultimately, the experiment demonstrated that vampire bats can convert amino acids into energy within 10 minutes and use it as fuel for long endurance runs.
This process makes vampires unique among mammals. These findings suggest that vampire metabolism is actually closer to that of blood-drinking tsetse flies than other bat species. And although flying requires significantly more energy than running, researchers believe that vampires burn amino acids to fly as well.
“What’s even more surprising is that you can maintain this extremely high exercise rate for long periods of time simply by burning protein stores in your muscles,” Welch added. It’s something we can only dream of. ”
