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Erdener ŞE, Tang J, Sajjadi A, Kılıç K, Kura S, Schaffer CB, Boas DA. Spatio-temporal dynamics of cerebral capillary segments with stalling red blood cells. J Cereb Blood Flow Metab 2019; 39:886-900. [PMID: 29168661 PMCID: PMC6501506 DOI: 10.1177/0271678x17743877] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Optical coherence tomography (OCT) allows label-free imaging of red blood cell (RBC) flux within capillaries with high spatio-temporal resolution. In this study, we utilized time-series OCT-angiography to demonstrate interruptions in capillary RBC flux in mouse brain in vivo. We noticed ∼7.5% of ∼200 capillaries had at least one stall in awake mice with chronic windows during a 9-min recording. At any instant, ∼0.45% of capillaries were stalled. Average stall duration was ∼15 s but could last over 1 min. Stalls were more frequent and longer lasting in acute window preparations. Further, isoflurane anesthesia in chronic preparations caused an increase in the number of stalls. In repeated imaging, the same segments had a tendency to stall again over a period of one month. In awake animals, functional stimulation decreased the observance of stalling events. Stalling segments were located distally, away from the first couple of arteriolar-side capillary branches and their average RBC and plasma velocities were lower than nonstalling capillaries within the same region. This first systematic analysis of capillary RBC stalls in the brain, enabled by rapid and continuous volumetric imaging of capillaries with OCT-angiography, will lead to future investigations of the potential role of stalling events in cerebral pathologies.
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Affiliation(s)
- Şefik Evren Erdener
- 1 Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Jianbo Tang
- 1 Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Amir Sajjadi
- 1 Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Kıvılcım Kılıç
- 2 Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Sreekanth Kura
- 1 Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Chris B Schaffer
- 3 Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - David A Boas
- 1 Optics Division, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,2 Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
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Hauck EF, Apostel S, Hoffmann JF, Heimann A, Kempski O. Capillary flow and diameter changes during reperfusion after global cerebral ischemia studied by intravital video microscopy. J Cereb Blood Flow Metab 2004; 24:383-91. [PMID: 15087707 DOI: 10.1097/00004647-200404000-00003] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The reaction of cerebral capillaries to ischemia is unclear. Based on Hossmann's observation of postischemic "delayed hypoperfusion," we hypothesized that capillary flow is decreased during reperfusion because of increased precapillary flow resistance. To test this hypothesis, we measured cerebral capillary erythrocyte velocity and diameter changes by intravital microscopy in gerbils. A cranial window was prepared over the frontoparietal cortex in 26 gerbils anesthetized with halothane. The animals underwent either a sham operation or fifteen minutes of bilateral carotid artery occlusion causing global cerebral ischemia. Capillary flow velocities were measured by frame-to-frame tracking of fluorescein isothiocyanate labeled erythrocytes in 1800 capillaries after 1-hour reperfusion. Capillary flow velocities were decreased compared to control (0.25 +/- 0.27 mm/s vs. 0.76 +/- 0.45 mm/s; P<0.001). Precapillary arteriole diameters in reperfused animals were reduced to 76.3 +/- 6.9% compared to baseline (P<0.05). Capillary diameters in reperfused animals (2.87 +/- 0.97 microm) were reduced (P<0.001) compared to control (4.08 +/- 1.19 microm). Similar reductions of precapillary (24%) and capillary vessel diameters (30%) and absolute capillary flow heterogeneity indicate that delayed (capillary) hypoperfusion occurs as a consequence of increased precapillary arteriole tone during reperfusion.
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Affiliation(s)
- Erik F Hauck
- Divison of Neurosurgery, University of Texas Medical Branch, Galveston, USA
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Lauro KL, LaManna JC. Adequacy of cerebral vascular remodeling following three weeks of hypobaric hypoxia. Examined by an integrated composite analytical model. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 411:369-76. [PMID: 9269451 DOI: 10.1007/978-1-4615-5865-1_47] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- K L Lauro
- Department of Pulmonary and Critical Care Medicine, Case Western Reserve University, Cleveland, Ohio, USA
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Bereczki D, Wei L, Otsuka T, Acuff V, Pettigrew K, Patlak C, Fenstermacher J. Hypoxia increases velocity of blood flow through parenchymal microvascular systems in rat brain. J Cereb Blood Flow Metab 1993; 13:475-86. [PMID: 8478406 DOI: 10.1038/jcbfm.1993.62] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The postulation that hypoxia increases local cerebral blood flow (lCBF) mainly by perfusing more capillaries (the capillary recruitment hypothesis) was tested in awake adult male Sprague-Dawley rats exposed to 10% O2 and control rats. The [14C]iodoantipyrine technique was used to measure lCBF. Local cerebral blood volume was determined by measuring plasma and red cell distribution spaces within the brain parenchyma with 125I-labeled serum albumin (RISA) and 55Fe-labeled red cells (RBC), respectively. Tissue radioactivity in 44 brain areas was estimated by quantitative autoradiography. Hypoxia raised lCBF by 25-90% in all brain areas. In about one-quarter of the brain areas, the rise in blood flow was associated with a small increase in microvascular plasma and blood volumes. This change in blood volume, which could be the result of perfusing more parenchymal microvessels and/or increasing parenchymal microvessel diameter, is not sufficient to account for the observed rise in lCBF. In the remaining areas the RISA, RBC, and blood spaces were either unchanged or only marginally increased by hypoxia. For this hypoxic perturbation, the major mechanism of raising blood flow appears to be increased velocity of microvessel perfusion and not perfusion of more capillaries. These findings provide only limited support for the capillary recruitment hypothesis.
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Affiliation(s)
- D Bereczki
- Department of Neurological Surgery, State University of New York, Stony Brook 11794-8122
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Hudetz AG. Computer simulation of erythrocyte transit in the cerebrocortical capillary network. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1992; 317:659-70. [PMID: 1288186 DOI: 10.1007/978-1-4615-3428-0_79] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The relationship between erythrocyte flow path length and transit time was studied using a probabilistic computer simulation of erythrocyte transit in morphometrically reconstructed cerebrocortical microvascular network of the rat. The results suggest (1) a near-cubic relationship between erythrocyte flow and vessel diameter, (2) preferential pathways of erythrocyte flow, (3) an exponential relationship between erythrocyte transit time and flow path length.
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Affiliation(s)
- A G Hudetz
- Department of Physiology, Medical College of Wisconsin, Milwaukee
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Hudetz AG. Dependence of cerebral capillary hematocrit on red cell flow separation at bifurcations: a computer simulation study. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1990; 277:31-4. [PMID: 2096637 DOI: 10.1007/978-1-4684-8181-5_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The influence of preferential red cell entry into microvascular branches with higher flow on microvessel hematocrit distribution was studied by mathematical modeling in a reconstructed cerebrocortical microvascular network. More heterogeneous hematocrit distribution was obtained at stronger cell partitioning. Small variations in the cell separation parameter resulted in significantly different hematocrit distributions. The significance of these findings in vivo should be further evaluated.
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Affiliation(s)
- A G Hudetz
- Department of Physiology, Medical College of Wisconsin, Milwaukee
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