Two-Photon Imaging of Cortical Surface Microvessels Reveals a Robust Redistribution in Blood Flow after Vascular Occlusion (original) (raw)
Figure 1
TPLSM of Fluorescently Labeled Cortical Vasculature In Vivo
(A) Low-magnification TPLSM image of fluorescently labeled brain vasculature in rat parietal cortex. The axes indicate the rostral (R) and medial (M) directions. In the inset is an image of latex-filled brain vasculature taken from Scremin [1], with a box that indicates the approximate size and location of a typical craniotomy and an arrow that identifies the MCA.
(B) Tracing of the surface arterial vascular network from the image in (A). Branches of the MCA are indicated, as are representative examples of the communicating arterioles (CA) that form the surface network and diving arterioles (DA) that supply cortex.
(C) Maximal projection of a TPLSM image stack through a cortical arteriole. The dark line indicates the location where the line-scan data were taken, and the arrow represents the direction of flow obtained from these scans.
(D) Line-scan data from the vessel in (C) to quantify the flow of RBCs. Each scan is displayed below the previous one, forming a space–time image with time increasing from top to bottom of the image. The dark streaks running from upper right to lower left are formed by the motion of the non-fluorescent RBCs. The RBC speed is given by the inverse of the slope of these streaks; the direction of flow is discerned from the sign of the slope.
(E) RBC speed along the center of the arteriole shown in (C) and (D) as a function of time. The periodic modulation of the RBC speed occurs at the approximately 6-Hz heart rate. The dotted line represents the temporal average of the speed.
(F) RBC speed in an arteriole, averaged over 40 s, as a function of the transverse position in the vessel along horizontal (y) and vertical (z) directions. The parabolic curve represents the laminar flow profile that most closely matches the data, i.e., s = _A_·(1 − r/R)2 where s is the speed of the RBCs, r is a radius from the origin and corresponds to either the y or z direction, R is the measured vessel radius of 26 μm, and A is a free parameter (A = 10 mm/s).