Kidney cells do not They filter the blood, they pump it. The finding could help detect and treat kidney disease.
Researchers from the Johns Hopkins University of USA studied the mechanical forces on kidney function, and discovered a previously unknown ‘pumping’ action of kidney cells.
Whole blood of your body passes through the kidneys dozens of times a day, passing through small tubes and filtering devices, before returning, already ‘clean’, to the bloodstream. But the mechanism of this process has been incomprehensible, since the epithelial cells lining these tubes were considered immobile.
To discover the secrets of this transport process of fluids, Sean Sun, a mechanical engineer from the North American university, developed a device that measures the mechanical forces generated by kidney cells, both healthy and diseased. “What we show is that kidney cells are pumps, not filters, and they generate forces,” explained Sun, co-author of the study published in Nature Communications.
The team observed how kidney epithelial cells function as mechanical fluid pumps. These actively created a pressure gradient in the fluid that propelled it in a certain direction, much like a conventional domestic water pump.
Subsequently, the The team investigated possible changes in the function of these cells in disease and found that diseased cells pumped fluid in the opposite direction to healthy cells. This changed in the direction of pressure in the renal tubules, changed the pressure profile of the renal tube, resulting in a change in its shape and morphology.
The researchers then tested a drug called Tolvaptan, which is used to slow the progression of ADPKD, a common aggressive, inherited disorder in which the kidney develops fluid-filled cysts, resulting in an enlarged kidney.
Researchers found that the drug causes cells to decrease their pumping flux and pressure gradient, suggesting that the drug works by reducing stress on tissues and, thus, slowing down the rate at which cysts form.
The team notes that the device they developed could be used as a discovery tool for new methods of treatment of ADPKD and other kidney diseases.