title: Key role of tissue plasminogen activator in neurovascular coupling.
abstract: The increase in blood flow evoked by synaptic activity is essential for normal brain function and underlies functional brain imaging signals. Nitric oxide, a vasodilator released by NMDA receptor activation, is critical for the flow increase, but the factors linking NMDA receptor activity to nitric oxide-dependent hyperemia are poorly understood. Here, we show that tissue plasminogen activator (tPA), a serine protease implicated in NMDA receptor signaling, is required for the flow increase evoked by somatosensory stimulation. tPA acts by facilitating neuronal nitric oxide release, but this effect does not involve enhancement of NMDA currents or the associated intracellular Ca(2+) rise. Rather, the evidence suggests that tPA controls NMDA-dependent nitric oxide synthesis by influencing the phosphorylation state of neuronal nitric oxide synthase. These findings unveil a previously unrecognized role of tPA in vital homeostatic mechanisms coupling NMDA receptor signaling with nitric oxide synthesis and local cerebral perfusion.
authors.affiliation: Division of Neurobiology, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10021, USA.
authors.forename: Laibaik
authors.initials: L
authors.lastname: Park
authors.forename: Eduardo F
authors.initials: EF
authors.lastname: Gallo
authors.forename: Josef
authors.initials: J
authors.lastname: Anrather
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.forename: Erin H
authors.initials: EH
authors.lastname: Norris
authors.forename: Justin
authors.initials: J
authors.lastname: Paul
authors.forename: Sidney
authors.initials: S
authors.lastname: Strickland
authors.forename: Costantino
authors.initials: C
authors.lastname: Iadecola
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D004594:Electrophysiology; D006940:Hyperemia / Q000139:chemically induced / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D012039:Regional Blood Flow; D010959:Tissue Plasminogen Activator / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate; D009569:Nitric Oxide; D016202:N-Methylaspartate; D052248:Nitric Oxide Synthase Type I; D010959:Tissue Plasminogen Activator; D002118:Calcium