title: Initial oligemia with capillary flow stop followed by hyperemia during K+-induced cortical spreading depression in rats.
abstract: Local cerebral blood volume (CBV) and capillary flow changes in regions of depolarizing neurons during K(+)-induced cortical spreading depression (CSD) in the cerebral cortex of alpha-chloralose-urethane-anesthetized rats were examined employing a transillumination (550 nm) video system. Capillary flow was calculated as the reciprocal of mean transit times of blood in pixels of 40 microm x 40 microm, each of which contains a few capillaries. Potassium microinjection into the cortex evoked repetitive wave-ring spreads of oligemia at a speed of ca. 2.33 +/- 0.48 mm/min. During the spread of CSD, tracer (either saline or carbon black) was injected into the internal carotid artery. Colocated with the oligemic wave, we detected capillary flow stop as evidenced by disappearance of the hemodilution curves. At any location in the region of interest within the cerebral cortex, we observed cyclic changes of capillary flow stop/hyperperfusion in synchrony with oligemia/hyperemia fluctuations. The initial flow stop and oligemia were ascribed to capillary compression by astroglial cell swelling, presumably at the pericapillary endfeet, since the oligemia occurred before larger vessel changes. We conclude that local depolarizing neurons can decrease adjacent capillary flow directly and immediately, most likely via astroglial cell swelling, and that the flow stop triggers upstream arteriolar dilatation for capillary hyperperfusion.
authors.affiliation: Department of Neurology, School of Medicine, Keio University, Tokyo, Japan. mtomita@sc.itc.keio.ac.jp
authors.forename: Minoru
authors.initials: M
authors.lastname: Tomita
authors.forename: Istvan
authors.initials: I
authors.lastname: Schiszler
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tomita
authors.forename: Norio
authors.initials: N
authors.lastname: Tanahashi
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Takeda
authors.forename: Takashi
authors.initials: T
authors.lastname: Osada
authors.forename: Norihiro
authors.initials: N
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D002196:Capillaries / Q000502:physiology; D002540:Cerebral Cortex / Q000098:blood supply*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D013181:Cortical Spreading Depression / Q000187:drug effects / Q000502:physiology*; D006940:Hyperemia / Q000503:physiopathology*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D018715:Microscopy, Video / Q000379:methods*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D011188:Potassium