title: Arteriole dilation to synaptic activation that is sub-threshold to astrocyte endfoot Ca2+ transients.
abstract: Ca(2+)-dependent pathways in neurons and astrocyte endfeet initiate changes in arteriole diameter to regulate local brain blood flow. Whether there exists a threshold of synaptic activity in which arteriole diameter is controlled independent of astrocyte endfeet Ca(2+) remains unclear. We used two-photon fluorescence microscopy to examine synaptically evoked synthetic or genetic Ca(2+) indicator signals around penetrating arterioles in acute slices of the rat neocortex. We discovered a threshold below which vasodilation occurred in the absence of endfeet Ca(2+) signals but with consistent neuronal Ca(2+) transients, suggesting endfoot Ca(2+) is not necessary for activity-dependent vasodilation under subtle degrees of brain activation.
authors.affiliation: Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.|Department of Physiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors.forename: Ádám
authors.initials: Á
authors.lastname: Institoris
authors.affiliation: Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: David George
authors.initials: DG
authors.lastname: Rosenegger
authors.affiliation: Hotchkiss Brain Institute, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Grant Robert
authors.initials: GR
authors.lastname: Gordon
mesh_terms: D000818:Animals; D001160:Arterioles / Q000502:physiology; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D008297:Male; D019579:Neocortex / Q000098:blood supply / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000378:metabolism*; D014664:Vasodilation / Q000502:physiology*