A team of Japanese scientists has shown it is possible for mammals to absorb oxygen via the anus. Intrigued by how certain sea creatures breathe through their intestines in emergencies, researchers at Tokyo Medical and Dental University were able to prove the same was true under experimental circumstances for mice, rats and pigs.
They say the finding, published in Med, might also apply to humans who are in respiratory distress when ventilators are not available or inadequate. For higher order animals, respiration involves breathing in oxygen and excreting carbon dioxide using lungs or gills.
Some species however have evolved alternate ventilatory mechanisms. Loaches, catfish, sea cucumbers and orb-weaving spiders can also use their hindgut to oxygenate to survive in emergencies. This is called enteral ventilation via anus, or EVA.
“The rectum has a mesh of fine blood vessels just beneath the surface of its lining, which means drugs given through the anus are readily absorbed into the bloodstream,” lead author Ryo Okabe said.