title: Temporal dynamics of brain tissue nitric oxide during functional forepaw stimulation in rats.
abstract: We report the first dynamic measurements of tissue nitric oxide (NO) during functional activation of rat somatosensory cortex by electrical forepaw stimulation. Cortical tissue NO was measured electrochemically with rapid-responding recessed microelectrodes (tips <10 microm). Simultaneous blood flow measurements were made by laser-Doppler flowmetry (LDF). NO immediately increased, reaching a peak 125.5 +/- 32.8 (SE) nM above baseline (P < 0.05) within 400 ms after stimulus onset, preceding any LDF changes, and then returned close to prestimulus levels after 2 s (123 signal-averaged trials, 12 rats). Blood flow began rising after a 1-s delay, reaching a peak just before electrical stimulation was ended at t = 4 s. A consistent poststimulus NO undershoot was observed as LDF returned to baseline. These findings complement our previous study (B. M. Ances et al., 2001, Neurosci. Lett. 306, 106-110) in which a transient decrease in rat somatosensory cortex tissue oxygen partial pressure was found to precede blood flow increases during functional activation.
authors.affiliation: Department of Physiology, Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Donald G
authors.initials: DG
authors.lastname: Buerk
authors.forename: Beau M
authors.initials: BM
authors.lastname: Ances
authors.forename: Joel H
authors.initials: JH
authors.lastname: Greenberg
authors.forename: John A
authors.initials: JA
authors.lastname: Detre
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D003196:Computer Graphics; D003626:Data Display; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005552:Forelimb / Q000294:innervation*; D017078:Laser-Doppler Flowmetry; D008297:Male; D008839:Microelectrodes; D009569:Nitric Oxide / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012815:Signal Processing, Computer-Assisted; D013003:Somatosensory Cortex / Q000098:blood supply / Q000502:physiology*
chemical_list: D009569:Nitric Oxide