A Brock-led research team has found for the first time that a chemical released by the sympathetic nervous system regulates blood pressure under resting conditions, a discovery that may lead to new treatments for high blood pressure.

The sympathetic nervous system is involved in the “fight or flight” response in stressful situations. Electrical impulses that travel along nerves release chemicals called neurotransmitters that cause the heart to beat faster and blood vessels to constrict, leading to high blood pressure.

The release of one of these chemicals, Neuropeptide Y, has traditionally been thought to be reserved for periods when the body is under stress, like during maximal exercise.

But Assistant Professor of Kinesiology Stephen Klassen and his research team have found that this chemical participates in blood pressure regulation when the body is at rest, which he says, “may have important implications for the development of high blood pressure.”

Six healthy young people were recruited for the study. Researchers measured the levels of neuropeptide Y and another neurotransmitter called norepinephrine in the participants’ blood while they were laying down.

During continuous blood pressure measurements, the researchers recorded electrical impulses travelling from participants’ brains to their blood vessels instructing the blood vessels to constrict.

Participants then received a drug called dexmedetomidine, which reduced sympathetic nerve activity and allowed the team to study sympathetic nerve release of neuropeptide Y.

Through “letting off the gas pedal” in charge of constricting blood vessels, the reduction in sympathetic activity caused a decrease in blood pressure, says Klassen.

When the researchers examined the levels of neuropeptide Y and norepinephrine, they had also dropped significantly.

“The team interprets these findings to mean that sympathetic nerves release neuropeptide Y, which is important for resting blood pressure regulation,” says Klassen.

Health Sciences PhD candidate Nathan Iannarelli, one of the researchers on the 12-member North American team, says the study “reveals that the brain uses neuropeptide Y to communicate with the blood vessels and regulate resting blood pressure.”

Klassen says this new knowledge can lay the groundwork for innovative blood pressure interventions.

“Many individuals with hypertension are not able to lower their blood pressure with currently available medications,” says Klassen. “Perhaps researchers need to consider developing blood pressure lowering medications that target neuropeptide Y.”

The findings of Klassen and his team are described in their study “Human sympathetic neuronal discharge and recruitment patterns regulate neuropeptide Y bioavailability,” published late last year in American Journal of Physiology.

Brock researchers  Klassen, Iannarelli and first-year master’s student Julia Spafford worked with investigators from Western University and the Mayo Clinic in Minnesota.

Supporting the team’s research were grants from the Natural Sciences and Engineering Research Council of Canada, which is funded by the Government of Canada, the Ontario Graduate Scholarship Program, Brock University and the U.S. National Institutes of Health.