Listening in on brain's 'music'

By ANGELA GREGORY

Ground-breaking research at Auckland University may help people with high blood pressure by turning down the volume of the "music" in their brains.

The "music" consists of electronic signals, sent out by the sympathetic nervous system, which control blood supply around the body.

Until now, blood pressure was thought to be controlled mainly by the heart and hormones.

But researchers at the university School of Medicine are demonstrating through their award-winning technology how the nervous system's signals play a more significant role in the long-term control of blood pressure than was previously thought.

The research has implications for the one in 10 New Zealanders who has high blood pressure, or hypertension, which increases the chance of strokes or heart disease.

The technology, designed by physiologists and electrical engineers, consists of a device which can record signals from the the sympathetic nervous system.

Team leader Dr Simon Malpas said the research opened up a new area for the control of blood pressure.

The sympathetic nervous system was usually thought of as a rapid-response system, for instance stopping a person fainting if he or she stood up suddenly.

"We now know that it is very much more than a short-term function and acts on the kidney to regulate the excretion of salt and water, as well as hormone production. Signals increase in the early stages of developing high blood pressure.

"What this means in the long term is that treatments for hypertension could target the sympathetic nervous system, turning the volume up or down."

Dr Malpas said research into blood pressure had been held back because there had been no way to monitor the sympathetic nervous system for more than a few hours.

"In the past we've had to insert a needle into a nerve, usually in the arm or leg. It's unpleasant and the reliability of the signals is not great."

The wireless technology allowed long-term monitoring of the signals from the system to the kidney, and could measure blood pressure at the same time.

A coin-sized unit, with an amplifier and transmitter, sends signals to a remote receiver, which processes the recordings on a computer using specifically designed software.

When amplified, the electrical signals sound like a chugging steam train.

Dr Malpas said potential long-term applications included stick-on, peel-off transmitters so patients no longer had to be tied to monitors in areas such as intensive care.

The team's work has been recognised by the American Physiological Society, which awarded Dr Malpas its Arthur C. Guyton Award for Excellence in Integrative Physiology.