Experiment 3: The effect of NBCe1 knockdown in astrocytes on neuronal activity-dependent increases in local cerebral blood flow in the somatosensory cortex

Fast scan cyclic voltammetry was used to record the neurovascular response in the S1FL region of the somatosensory cortex in mice. The expression of the neurovascular response was assessed from the recordings of changes in brain tissue PO₂, previously reported to accurately match BOLD responses to somatosensory stimuli²². Mice (3–4 months old) were anesthetized with a mixture of ketamine/xylazine (100 mg kg⁻¹/10 mg kg⁻¹, i.p.). The head was secured in a stereotaxic frame. Oxygen-enriched room air was supplied to the animal breathing unaided throughout the experiment. Electrical forepaw stimulations (300 µs pulse width, 3 Hz, 1.5 mA) were applied to activate somatosensory pathways and evoke the neurovascular response in the S1FL region. S1FL tissue PO₂ changes evoked by three stimulations (20 s long) were averaged within each animal to obtain a profile of the response for each subject. Peak of the response (difference in PO₂ between the value taken at the end of the stimulation period and the pre-stimulus baseline, expressed in mmHg) and integral (area under the curve, AUC) were compared between the astrocyte specific NBCe1 deficient (NBCe1^flox/flox:GLAST^CreERT2/+ animals treated with tamoxifen, n = 7) and two control groups of mice (NBCe1^flox/flox:GLAST^CreERT2/+ animals given vehicle, n = 7; and NBCe1^flox/flox:GLAST^+/+ mice treated with tamoxifen, n = 8).