Astrocyte-mediated control of cerebral blood flow.
Local increase in blood flow during neural activity forms the basis for functional brain imaging, but its mechanism remains poorly defined. Here we show that cortical astrocytes in vivo possess a powerful mechanism for rapid vasodilation. We imaged the activity of astrocytes labeled with the calcium (Ca(2+))-sensitive indicator rhod-2 in somatosensory cortex of adult mice. Photolysis of caged Ca(2+) in astrocytic endfeet ensheathing the vessel wall was associated with an 18% increase in arterial cross-section area that corresponded to a 37% increase in blood flow. Vasodilation occurred with a latency of only 1-2 s, and both indomethacin and the cyclooxygenase-1 inhibitor SC-560 blocked the photolysis-induced hyperemia. These observations implicate astrocytes in the control of local microcirculation and suggest that one of their physiological roles is to mediate vasodilation in response to increased neural activity.
Takano
Takahiro
T
Center for Aging and Developmental Biology, Department of Neurosurgery, University of Rochester Medical School, 601 Elmwood Avenue, Rochester, New York 14642, USA. Takahiro_Takano@URMC.Rochester.edu
Tian
Guo-Feng
GF
Peng
Weiguo
W
Lou
Nanhong
N
Libionka
Witold
W
Han
Xiaoning
X
Nedergaard
Maiken
M
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001921:Brain / Q000098:blood supply* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D051545:Cyclooxygenase 1 / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008833:Microcirculation; D014664:Vasodilation / Q000502:physiology*
D008565:Membrane Proteins; D051545:Cyclooxygenase 1; C496512:Ptgs1 protein, mouse; D002118:Calcium