Gordon, Grant Robert J.Shin, Steven Seungjae2018-05-152018-05-152018-05-10Shin, S. S. (2018). Fundamental Mechanisms of Astrocyte and Cerebrovascular Regulation by Potassium in the Neocortex (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/31919http://hdl.handle.net/1880/106638Astrocytes can control local cerebral arteriole tone through Ca2+ dependent mechanisms. Modest elevations of the external K+ concentration in the brain are thought to have little effect on astrocyte free Ca2+, yet K+ dilates parenchymal arterioles. It remains unclear whether fluctuations in external K+, within the low to moderate range, controls arteriole diameter through an astrocyte Ca2+ dependent mechanism. Using relative and quantitative two-photon fluorescence Ca2+ imaging in acute brain slices of the somatosensory cortex from Sprague Dawley rats, we found that elevations in external K+ from 2.5 mM to 3.5 or 5.0 mM decreased astrocyte free Ca2+ and caused arteriole dilation. The phenomenon relied on external Ca2+, Cl-, and bicarbonate, as well as, unexpectedly, the potassium chloride cotransporter (KCC). These data highlight novel aspects of K+-astrocyte dynamics that involve the subtle regulation of free astrocyte Ca2+ via Cl- and bicarbonate fluxes with corresponding changes to arteriole tone.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.AstrocyteCalcium ImagingCerebrovasculaturePotassiumTwo-Photon MicroscopyNeurosciencemaster thesis10.11575/PRISM/31919