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. Author manuscript; available in PMC: 2010 Aug 16.
Published in final edited form as: Ann Neurol. 2010 Feb;67(2):221–229. doi: 10.1002/ana.21871

FIGURE 1.

FIGURE 1

Microembolic hypoperfusion triggers cortical spreading depression (CSD). (A) Representative tracings show the time course of cerebral blood flow (CBF) reduction after intracarotid air, microsphere, or cholesterol injection (blue circles). Both air and microspheres abruptly but transiently decreased CBF to ≤25% of baseline, whereas the hypoperfusion after cholesterol microemboli was less predictable and fluctuated over time (note the compressed time scale for the cholesterol data). CSD (red circles) occurred within a few minutes after air or microsphere embolization, but was more delayed after cholesterol microemboli. CSDs were detected by the characteristic slow extracellular direct current (DC) shift shown in C and by a propagating wave of hypoperfusion. (B) Full-field images of CBF taken at the denoted time point between microembolization (red arrows in A) and CSD onset showing the spatial extent of hypoperfusion. Air and microspheres reduced CBF within the ipsilateral middle cerebral artery (MCA) and bilateral anterior cerebral artery territories, whereas cholesterol-induced hypoperfusion was more restricted to ipsilateral MCA branches. Red squares show the regions of interest within which the CBF time courses (shown in A) were quantified for each type of microemboli. The orientation of the imaging field over the mouse skull is shown in the inset (left). The inset shows the position of the rectangular imaging field. (C) Extracellular DC potential shifts characteristic of CSD were triggered by intracarotid microembolization with air (left), microsphere (middle), or cholesterol (right), and recorded by intracortical glass micropipettes within the ipsilateral MCA territory simultaneously with the laser speckle flowmetry. (D) The timing of CSD after air (triangles), microsphere (crosses), and cholesterol microemboli (squares) is shown for each animal. Both air and microspheres evoked a CSD within a few minutes after microembolization, whereas the onset of CSD was significantly delayed after cholesterol microemboli.