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New findings on the role of calcium channels in brain blood flow


Calgary, AB – Researchers at the University of Calgary have identified how calcium channels in the cerebral arteries play an important role in controlling blood flow to the brain. Scientists performed the first human-based study to look at human cerebral circulation — the movement of blood through the network of blood vessels that go to the brain. The results of their study were recently published in the Journal of General Physiology.

With the study’s main focus on smooth muscle cells, the study’s lead author, Osama Harraz, PhD, along with his research team studied the contraction activity of smooth muscle cells of human brain arteries in response to pressure changes. This type of constriction, known as arterial tone, regulates blood flow to the brain and occurs if calcium is present to enter the cell.

“Calcium ion is one of the most essential second messengers in a biological system,” said Harraz, a previous PhD candidate in the Cumming School of Medicine and member of the Hotchkiss Brain Institute (HBI) and the Libin Cardiovascular Institute. “It controls all cellular functions including smooth muscle contraction; once calcium enters the cell there is a change in blood vessel diameter which alters blood flow to the brain.”

To reveal the identities and roles of the calcium channels for the first time in humans, Harraz and his research team collaborated with physicians in the Foothills Medical Centre and dissected smooth muscle cells from brain tissue from patients undergoing brain surgery.

Harraz said that for the first time they are able to use not only animal models but also to look at human cerebral circulation.

“By doing so, we are able to have a better understanding how different calcium channels control the arterial diameter and blood flow to the brain,” said Harraz, who is also a Vanier scholar.

Prior to the team’s discovery, only the L-type calcium channels were known to control human brain arteries. Researchers would typically use medications to try and treat reactions such as vascular spasms (constriction of the blood vessel) but occasionally that would be ineffective.

The team’s study has identified another subtype called T-type calcium channels and with this novel understanding, researchers can better identify new therapeutic targets and novel avenues for further studies.

“This study will assist with understanding the problems initiated in the human brain arteries,” said Harraz. “By now being able to identify the channels, we can better understand how to control this contraction which takes us one step closer to identifying new therapeutic targets for cardiovascular issues such as cerebral vasospasm and stroke.”

The study was funded by the Canadian Institutes of Health Research and Alberta Innovates Health Solutions.