The surgically implanted device reduced blood pressure in the animals by 40 percent and did not cause any major side effects, according to a study published May 9 in the Journal of Neural Engineering.
The creators of the device said it could one day offer a new option for people with high blood pressure who do not respond to existing treatments.
The device is a cuff that wraps around the vagal nerve, which extends from the brainstem to the thorax and abdomen. The nerve stimulates major blood vessels, the heart and other organs. The device affects only vagal nerve fibers that influence blood pressure, the researchers noted in a news release from the Institute of Physics.
In rats, the device lowered blood pressure but did not affect heart or breathing rate, according to the researchers at the University of Freiburg in Germany.
"As the device will require surgery, it is not intended to be the first port of call for treatment and will come into play when patients, for whatever reasons, are resistant to medication," study lead author Dennis Plachta said in the news release.
"Nevertheless, the long-term goal is to provide 'treatment-on-demand' for the patient, whereby the implantable device uses an intelligent circuit to record the activity of the patient, for instance when they are doing exercise, and adjust the blood pressure accordingly," he explained.
"We will now look to develop the implantable device further and investigate whether it interferes with existing medication, and ultimately test it on larger animals such as pigs and sheep," Plachta added.
Research carried out on animals often fails to produce similar results in humans.
The U.S. National Heart, Lung, and Blood Institute has more about high blood pressure.