Red blood cells stabilize flow in brain microvascular networks

Area of Science:

• Physiology
• Biophysics
• Microcirculation Research

Background:

• Capillaries are crucial for tissue oxygen and nutrient exchange.
• Regulation of blood flow in cortical capillary beds remains incompletely understood.

Purpose of the Study:

• To investigate the impact of red blood cells (RBCs) on microvascular flow in cortical capillary beds.
• To explore how RBC dynamics influence perfusion and hematocrit distribution.

Main Methods:

• In vivo measurements of microvascular flow.
• Blood flow simulations in anatomically accurate microvascular networks.
• Analysis of RBC partitioning at capillary bifurcations and its effect on vessel resistance.

Main Results:

• RBCs promote "well-balanced bifurcations" by equalizing outflow velocities.
• RBC dynamics cause hematocrit heterogeneity through unequal partitioning.
• Capillary diameter changes significantly alter local flow and RBC distribution, with a 10% dilation increasing flow by 21%.

Conclusions:

• RBC dynamics play a key role in regulating microvascular flow and perfusion in the brain.
• Well-balanced bifurcations contribute to robust tissue perfusion.
• Capillary diameter modulation and RBC distribution are essential for efficient oxygen and energy substrate supply.