Vasomotion delineates cerebral vascular dynamic features and participates in the homeostatic cerebral blood flow regulation

Myogenic spontaneous vasomotion refers to intrinsic ultra-slow (~ 0.1 Hz) oscillations in vessel tone, crucial for stabilizing cerebral blood flow and regulating cerebrospinal cord fluid flow. Recently developed quantification methods for quantitative study of vasomotion used diameter or radius indices to characterize vasomotion. However, the advantages of the radius index remain underexplored. Given the asymmetric movement of vascular walls, the radius index offers greater potential for finely describing vasomotion. A comprehensive radius vasomotion index is introduced to characterize vascular dynamics under various physiological and pathological conditions. Leveraging the enhanced sensitivity of radius index, we identified in arterioles not only the myogenic vasomotion, but also prominent oscillatory components at respiratory and heartbeat frequencies, validated by concurrent respiration and heart rate recordings. We also observed differences in vasomotion between the inner and outer sides of arteriolar bifurcations, including a notable weakening of vasomotion at inner side. Using blebbistatin, we demonstrated the regulatory role of vasomotion in cerebral blood flow. Notably, we found that myogenic vasomotion was profoundly disrupted in awake mice during the reperfusion phase following ischemic stroke. In venules, vasomotor activity was observed within both the myogenic and cardiac frequency bands and was markedly suppressed under anesthesia, while calcium oscillations in venular smooth muscle cells were not associated with myogenic vasomotion. In summary, our quantitative analysis of cerebral vascular network provides greater sensitivity and stability than the diameter index in characterizing vasomotion. Our findings underscore the utility of the radius-based approach in detecting subtle vascular dynamics and demonstrate the physiological authenticity of vasomotion frequency components.