They studied anal breathing in mammals not to win an Ig Nobel Prize, but to save lives

Produced by: Science Popularization China

Author: Li Jinjuan (Chinese Academy of Agricultural Sciences)

Producer: China Science Expo

What? Mammals can breathe through their anuses?

Recently, scientists from Japan and the United States discovered that mammals can actually take in oxygen through their anuses. This research not only won them the 2024 Ig Nobel Prize in Physiology, but more importantly, it may open up a whole new path for treating severe respiratory failure.

(Image source: References)

The amazing breathing skills of animals

The diversity of breathing methods in the vast animal kingdom is a natural wonder. We humans and most land animals breathe through our lungs, which seems to be a normal thing. However, when we look at the wider natural world, we will find that the methods used by various species are amazingly diverse.

Fish are a perfect example. They have evolved sophisticated gill structures that can efficiently extract dissolved oxygen from water. This breathing method adapted to the aquatic environment allows fish to swim freely in the vast underwater world.

In stark contrast is the respiratory system of insects. These tiny organisms have a network of tracheae throughout their bodies that can deliver oxygen directly to every cell. This efficient breathing method provides a constant supply of energy to support the insects' high activity.

However, the creativity of nature goes far beyond this. In order to adapt to their special living environment, some animals have evolved more amazing breathing methods.

Some animals, such as earthworms and frogs, are able to exchange gases directly through their moist skin. This method, called "cutaneous respiration," allows them to maintain life activities even in an oxygen-deficient environment.

Prominent skin folds of the Titicaca frog increase surface area for cutaneous respiration

(Image source: Wikipedia)

Water spiders are even smarter. They weave a web of air-filled bubbles underwater. This small "oxygen tank" allows them to move freely underwater without having to surface frequently. Even more amazing is that some freshwater turtles can absorb oxygen from the water through special gill-like tissues near their anus. This unique "gill breathing" method allows them to stay underwater for longer periods of time.

Queensland lungfish (lungfish usually breathe with gills, and can use their swim bladder as lungs when the water dries up)

(Image source: Wikipedia)

Inspiration strikes! Can't mammals breathe through their intestines?

When it comes to strange breathing methods, loaches are the epitome. Who would have thought that inspiration for saving lives would come from this small fish? Scientists have learned that some aquatic animals, such as loaches, can breathe through their intestines in oxygen-deficient environments. This gave the research team a flash of inspiration: if fish can do this, why can't mammals?

Scientists carefully studied the intestinal structure of loach and found that its hind intestine has a very thin layer of epithelium, which is full of blood vessels and red blood cells, which is simply a natural respiratory organ. This discovery made scientists very excited and decided to try their hand on mammals.

How does the intestine breathe? From gas to liquid

The research team developed two novel breathing methods: gas enteric ventilation (g-EVA) and liquid enteric ventilation (l-EVA).

The gas intestinal ventilation experiment is like a special "beauty treatment" for the mouse intestine. Scientists tried to thin the intestinal mucosa of mice to make it easier for oxygen to enter the blood. The results showed that this method can indeed improve the efficiency of oxygen absorption.

However, imagine "grinding the intestines" of patients in the hospital. This scene is so beautiful that it is almost unbearable to watch. Therefore, scientists have come up with a method of liquid intestinal ventilation. They use a special liquid called perfluorodecane (PFD), which can dissolve a large amount of oxygen. When this "oxygen water" is injected into the rectum of mice, the blood oxygen level of the mice can be significantly improved.

Amazing discovery: Butt breathing really works

It has to be said that the initial experimental results were jaw-dropping. Under simulated severe respiratory failure conditions, mice that received the "anal breathing" treatment not only survived, but also were alive and well.

Even more surprising is that mice that received liquid intestinal ventilation not only had higher blood oxygen levels, but also had significantly enhanced mobility. Their performance in a low-oxygen environment was like chicken blood.

In order to prove that this is not a special ability of mice, the research team also conducted experiments on pigs. The results showed that pigs can also increase their blood oxygen levels through "anal breathing", and the effect can last for nearly 20 minutes. Now, "sticking onions in pig noses" may really have to be changed to "sticking oxygen tubes in pig buttocks".

Is it safe to breathe through your anus?

Any new medical technology must pass the safety test, and the research results on the biological safety of perfluorodecane are reassuring.

Scientists tested the levels of perfluorodecane in the treated animals and found that the levels were so low that they were almost undetectable. This shows that perfluorodecane did not travel around the animals through the intestines. At the same time, the biochemical indicators of the experimental animals were normal, and their internal organs looked no different from those of their companions who had not "inhaled oxygen".

Overall, anal breathing appears to be safe, at least in the short term, and it paves the way for possible human trials in the future.

Taking a different approach: Anal breathing brings new hope to medicine

For the medical and physiological communities, the significance of this research goes far beyond just a smile. In certain emergency situations, such as severe asthma attacks or neonatal suffocation, rapid oxygen delivery may be the key to saving lives. Traditional respiratory support methods, such as ventilators or artificial lungs, although effective, often require complex equipment and professionals. In contrast, the "anal breathing" method is simple and direct, and may become a new tool for saving lives.

If this seemingly fantastic "intestinal breathing" technology can be successfully applied to the human body, its impact may go far beyond the field of emergency treatment. In the medical field, it may open up new possibilities for some special surgeries. For example, in some complex surgeries that require temporarily stopping the patient's normal breathing, this technology may provide a new way to supply oxygen, giving the surgical team more time and space for operation.

Not only that, this technology may bring new hope to patients with some rare lung diseases. Imagine that for patients with severely impaired lung function, "intestinal breathing" may become an effective auxiliary treatment. It may help these patients better maintain their lives and improve their quality of life while waiting for lung transplantation or other treatments.

Of course, we must admit that these ideas are still in the theoretical stage. To turn them into reality, a lot of research is needed to verify their feasibility and safety. Nevertheless, these potential application scenarios are still exciting.

Maybe one day, when a doctor says, "Take a deep breath," we'll have to ask, "With which organ?"

References:

1.Mammalian enteral ventilation ameliorates respiratory failure