Blood flow control

"Switch" in brain’s capillary network monitors activity

All it takes is the flip of a protein “switch” within the tiny wire-like capillaries of the brain to increase the blood flow that ensures optimal brain function. New research has uncovered that capillaries have the capacity to both sense brain activity and generate an electrical vasodilatory signal to evoke blood flow and direct nutrients to nourish hard-working neurons.

The brains vascular network, shown in this image, consists of arteries, which...
The brain's vascular network, shown in this image, consists of arteries, which penetrate into the brain to feed a vast capillary network, which is then drained by veins.
Source: Courtesy of Thomas Longden.

When there is an increase in brain activity, there is an increase in blood flow, says Thomas Longden, Ph.D., assistant professor of pharmacology at the Larner College of Medicine at the University of Vermont and first author of the study. “The area of the brain covered by the capillaries - the smallest blood vessels in the body - vastly surpasses the area covered by arterioles. This ideally positions them for monitoring neuronal activity and controlling blood flow.”

Understanding the mechanisms that precisely direct cerebrovascular blood flow to satisfy the brain’s ever-changing energy needs has, to date, eluded scientists. Neurons consume an enormous amount of the body’s energy supplies - about 20 percent - yet lack their own reserves, so are reliant on blood to deliver nutrients. Previously, capillaries were thought to be passive tubes and the arterioles were thought to be the source of action. Now, Longden and colleagues have discovered that capillaries actively control blood flow by acting like a series of wires, transmitting electrical signals to direct blood to the areas that need it most.

To achieve this feat, the capillary sensory network relies on a protein (an ion channel) that detects increases in potassium during neuronal activity. Increased activity of this channel facilitates the flow of ions across the capillary membrane, thereby creating a small electrical current that generates a negative charge—a rapidly transmitted signal—that communicates the need for additional blood flow to the upstream arterioles, which then results in increased blood flow to the capillaries.

The team’s study also determined that if the potassium level is too high, this mechanism can be disabled, which may contribute to blood flow disturbances in a broad range of brain disorders. “These findings open new avenues in the way we can investigate cerebral diseases with a vascular component,” says co-first author Fabrice Dabertrand, Ph.D., an assistant professor of pharmacology at the University of Vermont’s Larner College of Medicine.

Cerebrovascular illnesses like Alzheimer’s disease, CADASIL, and other conditions that cause cognitive decline can, in part, be a consequence of neurons not receiving enough blood flow and therefore not getting sufficient nutrients. “If you’re hungry, you’re not able to do your best work; it may be the same for neurons,” says Dabertrand, who adds that the group’s next phase of research will focus on exploring potential pathological factors involved in disabling the capillary potassium-sensing mechanism.


Source: University of Vermont

04.04.2017

Read all latest stories

Related articles

Photo

News • Large study

Blood test for Alzheimer’s highly accurate

When combined with genetic risk factors, the test was up to 93 percent accurate at identifying people at risk of Alzheimer's dementia.

Photo

News • Brain disorder

Using ultrasound to achieve permeability of blood vessels

CarThera, a French company based at the Brain and Spine Institute (ICM), that designs and develops innovative ultrasound-based medical devices to treat brain disorders, announces the publication on…

Photo

Article • Brain imaging

White matter hyperintensities: a valuable biomarker to assess mortality risk

White matter hyperintensities (WMH) on the brain seen on MRI represent a biomarker associated with a 50/50 risk of death within five years after a first incident acute ischemic stroke (AIS) or…

Related products

Alsachim - Dosimmune immunosupressant Alsachim – kit (CE-IVD or RUO)

Clinical Chemistry

Alsachim - Dosimmune immunosupressant Alsachim – kit (CE-IVD or RUO)

Alsachim, a Shimadzu Group Company
Alsachim – Dosinaco anticoagulant reagent kit (RUO)

Clinical Chemistry

Alsachim – Dosinaco anticoagulant reagent kit (RUO)

Alsachim, a Shimadzu Group Company
Beckman Coulter – Access Procalcitonin (PCT)

Immunoassays

Beckman Coulter – Access Procalcitonin (PCT)

Beckman Coulter Diagnostics
Beckman Coulter – Early Sepsis Indicator

Blood Cell Counter

Beckman Coulter – Early Sepsis Indicator

Beckman Coulter Diagnostics
Canon – Alphenix Biplane High Definition Detector

Bi-Plane

Canon – Alphenix Biplane High Definition Detector

Canon Medical Systems Europe B.V.
Canon – Vitrea Advanced Visualization

Reading

Canon – Vitrea Advanced Visualization

Canon Medical Systems Europe B.V.
Subscribe to Newsletter