Targeting endothelial ion signalling to rescue cerebral blood flow in cerebral disorders

The mechanism whereby an increase in neuronal activity (NA) leads to a local elevation in cerebral blood flow to supply the active neurons with oxygen and nutrients and remove the catabolic waste has been termed neurovascular coupling (NVC). Although it has long been thought that the vasoactive mediators involved in NVC are generated by neurons and astrocytes, recent evidence unveiled the crucial role of cerebrovascular endothelial cells in NVC. Brain capillary endothelial cells express a complement of ion channels, including inward-rectifier K⁺ (K_ir2.1) channels, Transient Receptor Potential Ankyrin 1 channels and N-methyl-d-aspartate receptors that enable them to sense NA and thereby initiate the retrograde transmission of both electrical (via endothelium-dependent hyperpolarization) and chemical (via intercellular Ca²⁺ waves also sustained by TRP Vanilloid 4 channels and inositol-1,4,5-trisphosphate receptors) signals that induce vasodilation in upstream pial arteries and parenchymal arteries. Notably, a defect in the endothelial ion channel machinery (particularly, K_ir2.1 channels) contributes to vascular cognitive impairment and dementia that features many cerebral disorders, including Alzheimer's disease, cerebral small vessel diseases, and traumatic brain injury. Targeting endothelial ion channels through appropriate pharmacological approaches might represent a hitherto unappreciated strategy to rescue CBF and prevent cognitive impairment and dementia in patients affected by cerebral disorders.