Penetrating arterioles are a bottleneck in the perfusion of neocortex. Proc Natl Acad Sci U S A

Department of Physics, University of California at San Diego, La Jolla, CA 92093, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 02/2007; 104(1):365-70. DOI: 10.1073/pnas.0609551104
Source: PubMed


Penetrating arterioles bridge the mesh of communicating arterioles on the surface of cortex with the subsurface microvascular bed that feeds the underlying neural tissue. We tested the conjecture that penetrating arterioles, which are positioned to regulate the delivery of blood, are loci of severe ischemia in the event of occlusion. Focal photothrombosis was used to occlude single penetrating arterioles in rat parietal cortex, and the resultant changes in flow of red blood cells were measured with two-photon laser-scanning microscopy in individual subsurface microvessels that surround the occlusion. We observed that the average flow of red blood cells nearly stalls adjacent to the occlusion and remains within 30% of its baseline value in vessels as far as 10 branch points downstream from the occlusion. Preservation of average flow emerges 350 mum away; this length scale is consistent with the spatial distribution of penetrating arterioles. We conclude that penetrating arterioles are a bottleneck in the supply of blood to neocortex, at least to superficial layers.

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Available from: Nozomi Nishimura
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    • "Two-photon microscopy [9] was the first technology to perform cellular imaging at depths of several hundred µm in the living brain, and has significantly impacted neuroscience research over the past 15 years. Recently, two-photon microscopy has emerged as an in vivo method to investigate changes in hemodynamics [10]–[12] and synaptic networks [13]–[16] in ischemic stroke and spreading depression [17], [18]. However, while two-photon microscopy achieves subcellular spatial resolution, the imaging speed, penetration depth, and field-of-view are limited. "
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    • "Physiologically, the intravascular oxygen tensions may indicate extreme tissue hypoxia surrounding the vessel. Microcirculation studies observing substantial cell death in the cortical layers around single descending arterioles following occlusion may have sampled similar latent branching vessels [24,30]. The inherent sensitivity of the phosphorescent quenching oximetry technique noted in Figs. "
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    • "In addition to visualizing vascular topology, we measured the diameter and blood flow speed and direction in individual vessels, as described previously [26]. For hemorrhages, we targeted cortical penetrating arterioles (PA), i.e. arterioles that branch from the surface arteriole network and dive into the brain to feed capillary beds [27]. These vessels were identified by tracing through the vascular network from readily-identifiable surface arterioles and we confirmed they were penetrating arterioles by checking that the blood flow direction was into the brain. "
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