FIGURE 8.
Propagation of SD across the dense cerebral vascular network and the neurovascular unit. SD invading the tissue profoundly impacts all cells and constituents of the cerebrovascular unit. The intense pandepolarization causes massive extracellular ionic, neurotransmitter, and metabolic changes. The cerebrovascular response is the result of numerous complex processes and interactions within the unit, mediated by key cell types and molecular signals, some of which are listed. The large number of mediators and modulators simultaneously released from multiple different cell types has made it extremely difficult to dissect the role of individual factors in the hemodynamic response, further complicated by the heterogeneity of the normal response among studies. Therefore, we have refrained from attempting a contrived representation of the vasomotor actions of each potential mediator or modulator, and instead summarized the available data in Table 1. EDHF, endothelium-derived hyperpolarizing factor; PACAP, pituitary adenylate cyclase activating peptide; NE, norepinephrine; NPY, neuropeptide Y; ACh, acetylcholine; SP, substance P; NK-A, neurokinin A.