A team of Japanese researchers at Tokyo Medical and Dental University wanted to know whether humans could one day absorb oxygen via their anus, so they decided to test the theory on mice, rats and pigs.
“The rectum has a mesh of fine blood vessels just beneath the surface of its lining, which means that drugs administered through the anus are readily absorbed into the bloodstream,” lead author Ryo Okabe said.
The team wondered whether oxygen could be delivered into the bloodstream in the same way. To answer the question, they decided to carry out experiments on mice, pigs and rats who were not given oxygen until they were almost dead.
First, the researchers pumped oxygen gas in their anus, but the mice only absorbed the oxygen if their intestinal wall was scraped to make it thinner.
The researchers rubbed the lining of the rectum so hard until the skin was broken to increase blood flow, which improved the effectiveness of oxygen delivery.
However, since breaking the skin of the rectum of humans would be unacceptable, the researchers looked at other ways to insert oxygen. They broke the skin of the anuses of animals to conclude they would never do that to humans.
They then tried delivering oxygen in liquid form. Mice and pigs were deprived of oxygen again until they were nearly dead before they got the liquid through their rectum. The scientists were happy that it worked.
They did not say how many animals died to do these tests and what level of suffering the animals endured.
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