A new study on rats has shed light on the relationship between salt intake and blood pressure regulation.
The study has been conducted by researchers at the University of Erlangen, the Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch and Regensburg, in collaboration with scientists from Finland and Austria.
Within the skin, they have detected a new storage area for salt in the body. They also found out that if the process behind this storage is defected, animals become hypertensive.
Salt is responsible for water regulation in the body. It is taken up by the gastro-intestinal (GI) tract and, in large part, excreted by the kidneys.
However, salt is also stored in cells and in the interstitium, the area between cells in the body.
Dr. Jens Titze and colleages have now shown that a high-salt diet in rats leads to the accumulation of salt in the interstitium in the skin. This process is carefully regulated by special white blood cells, the macrophages.
In those macrophages, the scientists found a gene regulator (transcription factor) called TonEBP (tonicity-responsible enhancer binding protein). TonEBP is activated in these cells in response to high salt and turns on a gene (VEGF-C - vascular endothelial growth factor C) that controls the production of lymphatic blood vessels. With high-salt diet the lymphatic vessels increase.
The researchers found that when these macrophages are depleted or if the receptor for VEGF-C is absent, the animals are not able to "store their salt" and become hypertensive.
However, this process and its relevance to human disease are not yet completely understood, researchers said.
The study is published in Nature Medicine.