13 September 2016
Size is everything when it comes to high blood pressure
The body's smallest organ dictates your blood pressure
The size of a grain of rice, the
carotid body, located between two major arteries that feed the
brain with blood, has been found to control your blood
pressure.
A team of clinical scientists at the
University of Bristol have found a new way to treat high blood
pressure (hypertension). The research study, entitled "Unilateral
carotid body resection in resistant hypertension: a safety and
feasibility trial," was led by
Professor Julian Paton at the University of Bristol, and
Dr Angus Nightingale (Cardiology Consultant) at the
Bristol Heart Institute, Bristol, and was published recently in
theJournal of American College of Cardiology: Basic to
Translational Science.
The research indicates that the carotid bodies appear to be a
cause of high blood pressure, and as such now offer a new target
for treatment.
The clinical team have shown that removing one carotid body from
some patients with high blood pressure caused an immediate and
sustained fall in blood pressure.
Dr Nightingale said: "The falls in blood pressure we have seen
are impressive - more than you would see with pharmacological
medication - and demonstrate the exciting potential there now is
for targeting the carotid body to treat hypertension."
The carotid bodies "sniff" the levels of oxygen in blood, and
when this falls they raise the alarm of a potential emergency by
signaling to the brain to increase breathing and blood pressure.
The effect is similar to having the thermostat in your home set too
high all the time.
Professor Paton explained: "Treating the carotid body is a novel
approach and a potential game changer as we believe we are reducing
one of the maincausesfor hypertension in many patients. High blood
pressure treatment typically tackles the symptoms targeting the end
organs such as the heart, kidneys and blood vessels, and not the
causes.
"Most importantly, we have developed some unique tests to assess
which patients have overactive carotid bodies. This now gives us a
way to personalise treatment, which is essential as there are
multiple reasons why high blood pressure develops" said Dr
Nightingale.
The clinical trial demonstrated that the carotid bodies in
patients who responded to resection had raised carotid body
activity. These patients breathed more at rest and produced
exaggerated breathing responses when the oxygen level in their
blood was lowered.
High blood pressure is the world's leading contributor to
mortality. In the UK, its cost to the National Health Service is
around £2 billion per year, and it remains poorly controlled,
triggering heart and renal failure, and strokes. The World Health
Organization has identified high blood pressure as the single most
important risk factor for the global burden of disease and
death.
"Although this surgical approach to controlling high blood
pressure was successful, we don't think this will be the solution
in the long term. We now need to find a drug that dampens down an
overactive carotid body and resets the blood pressure thermostat to
a normal level," Dr Nightingale said.
Professor Paton's team may have found such an alternative.
Recent animal studies published last week in
Nature Medicine, discovered that the energy molecule adenosine
tri-phosphate appears to be responsible.
"We are very excited by finding that we can turn down the alarm
signals emanating from the carotid body in conditions of
hypertension, yet it remains fully operational should an emergency
situation occur. The new drug target we found within the
carotid body is a receptor for the ATP molecule called the P2X3
receptor" explained Professor Paton.
Professor Paton said: "This approach may lead us to the first
novel anti-hypertensive treatment strategy in more than 15
years. It has taken almost 10 years of research effort,
working with colleagues from the University of Bristol, The
University Hospitals Bristol NHS Foundation Trust, Medical
University of Gdansk, Poland, the William Harvey Research
Institute, London, Dartmouth Medical School, USA, the University of
Sao Paulo, Brazil, the University of Auckland, New Zealand, Cibiem
Inc., and Afferent Pharmaceuticals. Nor would it have been possible
without funding from The British Heart Foundation."
Paper
'Purinergic
receptors in the carotid body as a new drug target for controlling
hypertension' by Julian Paton et al in Journal of American
College of Cardiology: Basic to Translational Science.
To arrange an interview with Professor Paton, please contact
Simon Davies at the University of Bristol press office on 0117 928
8086 or simon.l.davies@bristol.ac.uk
To arrange an interview with Dr Nightingale, please contact
Hannah Allen in the press office at University Hospitals Bristol
NHS on hannah.allen@uhbristol.nhs.uk
or 0117 342 3629
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