King’s College researchers have discovered that nitric oxide, which controls blood pressure, originates in nerves rather than in blood vessels as previously thought. Developing new drugs that target the nerves could help the millions of patients whose hypertension is not adequately controlled by drugs.
The team gave healthy patients a drug that blocked an enzyme in the nerves from producing nitric oxide. They found that cutting nitric oxide production boosted vascular resistance and raised blood pressure.
“Until now the majority of blood pressure drugs have focused on other pathways,” said Ajay Shah, lead scientist on the trial, in a statement. “Establishing that nerves releasing nitric oxide influence blood pressure, provides a new target for drugs and could eventually lead to more effective treatments for patients.”
About one-third of U.S. adults—around 75 million people—have high blood pressure, but only half of them have it under control, a CDC report says. Of the 35 million people with uncontrolled hypertension, about one-third don’t know they have high blood pressure, one-fifth are not being treated for it, and nearly half of them—more than 16 million—are being treated, but drugs and lifestyle changes aren’t enough to control their condition.
A range of medications may be used to control high blood pressure. They include beta blockers, which cause the heart to beat more slowly and with less force, and ACE inhibitors that block a hormone that narrows blood vessels. There are also "central-acting agents" such as clonidine, which dampen the nerve signals in the brain that cause blood vessels to contract.
But some patients have resistant hypertension, which doesn’t respond to treatment with a diuretic and at least two blood pressure meds.
“This study adds a very unexpected piece to the puzzle of blood pressure regulation," said Jeremy Pearson, associate medical director at the British Heart Foundation, which funded the study alongside King’s, the NIHR Biomedical Research Centre at Guy’s and St Thomas’ NHS Foundation Trust. "These results provide hope of new treatments for people with poorly controlled high blood pressure, which could prove crucial in preventing a heart attack or stroke.”