Cool Science

Salt and blood pressure - what is the link?

Associate Professor Fiona McDonald

Ever thought about what your kidneys do? Yes, they produce urine, and that may not seem very exciting. But, did you know that by altering the amount of sodium and water in your urine, your kidneys actually control your blood pressure? You might have heard that eating too much salt (sodium chloride) is bad for you. In fact, our bodies only need about 0.5g of salt each day - this is the amount of salt in 4 slices of bread, or in a few potato chips. You may eat up to 10g of salt per day but the excess salt is lost in the urine - quite a handy system, because too much salt can lead to high blood pressure.

One of the key players in your kidney's control of blood pressure is a sodium ion channel, under study in our laboratory. This channel forms a pore, or hole, in the cell's plasma membrane, to allow sodium ions to pass into cells from the urine and then be transported into your blood. In some people this channel doesn't function correctly, and too much sodium is retained by the body instead of being lost in the urine. These individuals have very high blood pressure, or hypertension. High blood pressure puts strain on organs such as the heart (because it has to pump extra blood), and kidney (because it has to filter the extra blood), and these organs may eventually develop serious disease.

We are doing experiments to find out how the sodium ion channel is controlled by other proteins, so we can learn more about how blood pressure is controlled.

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