Researchers have discovered that the Kidneys Act on Blood Differently Than We Think Before

Researchers have discovered that the Kidneys Act on Blood Differently Than We Think Before ...

Every drop of blood in your body will have passed through your kidneys dozens of times by this time tomorrow. Water saturated with waste is removed to form urine, and freshly cleaned blood returns into circulation.

A new research by Johns Hopkins mechanical engineer Sean Sun suggests this important task is unlikely to be quite as exact as previously thought.

"Everyone notices that kidneys filter blood, but conceptually that''s incorrect," says Sun.

"We showed that kidney cells are glands, not filters, and they are generating forces," says the author.

It is not for lack of looking that we did not realize this strange mechanical activity. Anatomists have known the kidney''s structure and its role in producing blood urine since the 17th century.

The organ''s ability to mix the passive osmosis and active shunting of various chemicals in order to balance our bodies'' salts, wastes, and water has been extensively studied in the body.

Pourtant, a kidney consists of kilometers of channels and tubules crammed into a space no bigger than your fist, thus posing a risk of sluggish plumbing deep inside.

Studies have shown that the tubules lining the cells can sense hydrostatic pressure and even respond; however, it''s not clear how or whether these changes might be rescheduled in some way.

It''s not easy to work out how fluids flow through these itty-bitty pipes, either. Any experiment to discover the hydraulics at work inside individual tubules would require some fantastic technology to detect stubborn forces.

Sun and colleagues from across the United States came up with a micro-fluidic kidney pump (MFKP) that involves patterned blocks and porous membranes capable of containing a growing of cells that line kidney tubules.

In response to squirts of fluid from a syringe, researchers examined variations in pressure across the tissue once the cells had settled into place.

As we''d expect, fluids near the cells were noticed in accordance with an increase in hydraulic pressure, which was greater towards one end of the tissue than the other.

Small changes in the pressure of fluids entering the tissues altered the arrangement of ion channels and its supporting structure, altering its shape and function, according to a close look at the proteins the cells were churning out.

Fluids, which flow from the blood into the kidney''s tubules, travel in part under the mechanical direction of the cells themselves, adding a substantial additional layer of operation that might help to explain a range of renal problems.

Researchers used antibodies obtained from individuals with the renal disease Autosomal dominant polycystic kidney disease (ADPKD) to measure how this behavior unfolds inside less-functional kidneys.

In this condition, cysts are often formed, distorting the tissue, increasing the likelihood of kidney stones and urinary tract infections. According to the research, the cells pumping in reverse, with the pressure gradient being changed from one end to another.

The dosage of ADPKD, which was approved by the FDA, was cleaned out of the cells, thus reducing stress on the tissues and thus reducing the rate at which cysts might form.

It''s possible that other tissues might have their own versions of a mechanical pumping system that allows them to adjust fluid pressures at their convenience. Sun and his team want to alter their device to test other tissues and organs.

Nature Communications has published this work.

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