Isolation and Functional Analysis of Arteriolar Endothelium of Mouse Brain Parenchyma

Cerebral blood flow is conveyed by vascular resistance arteries and downstream parenchymal arterioles. Steady-state vascular resistance to blood flow increases with decreasing diameter from arteries to arterioles that ultimately feed into capillaries. Due to their smaller size and location in the parenchyma, arterioles have been relatively understudied and with less reproducibility in findings than surface pial arteries. Regardless, arteriolar endothelial cell structure and function-integral to the physiology and etiology of chronic degenerative diseases-requires extensive investigation. In particular, emerging evidence demonstrates that compromised endothelial function precedes and exacerbates cognitive impairment and dementia. In the parenchymal microcirculation, endothelial K⁺ channel function is the most robust stimulus to finely control the spread of vasodilation to promote increases in blood flow to areas of neuronal activity. This paper illustrates a refined method for freshly isolating intact and electrically coupled endothelial "tubes" (diameter, ~25 µm) from mouse brain parenchymal arterioles. Arteriolar endothelial tubes are secured during physiological conditions (37 °C, pH 7.4) to resolve experimental variables that encompass K⁺ channel function and their regulation, including intracellular Ca²⁺ dynamics, changes in membrane potential, and membrane lipid regulation. A distinct technical advantage versus arterial endothelium is the enhanced morphological resolution of cell and organelle (e.g., mitochondria) dimensions, which expands the usefulness of this technique. Healthy cerebral perfusion throughout life entails robust endothelial function in parenchymal arterioles, directly linking blood flow to the fueling of neuronal and glial activity throughout precise anatomical regions of the brain. Thus, it is expected that this method will significantly advance the general knowledge of vascular physiology and neuroscience concerning the healthy and diseased brain.