The Modular Organization of the Pial Arterial System in Phylogeny

Mchedlishvili, G. I.; Kuridze, Nina

doi:10.1038/jcbfm.1984.57

Cited by 48 publications

(31 citation statements)

References 13 publications

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“…The effect of Paco2 on ECBV (Fig. 1) strongly supports the prominent role of extraparenchymal vascular bed in the vasodilatory adaptation to hypercapnia (Raper et aI., 1971;Mchedlishvili and Kuridze, 1984). Under these circumstances, ECBV, which can increase at the most by 55%, appears to be the main location of the cerebral vascular reserve.…”

Section: Cerebral Blood Volumementioning

confidence: 63%

“…In the case of continuous capillary perfusion, blood flow regulation is under the unique control of vasomotion. This muscular control is located mainly outside the parenchyma itself, in the cere bral arteries, as well as in pial arteries and arterioles (Mchedlishvili and Kuridze, 1984); these vessels, acting as regulators of the cerebral vascular re-serve, determine the flow rate in the brain capillary network. By contrast, if the total capillary network is intermittently perfused, the adaptation of the ce rebral blood flow to high-flow conditions could also be dependent on the opening of previously closed capillaries.…”

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confidence: 99%

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Induced Response to Hypercapnia in the Two-Compartment Total Cerebral Blood Volume: Influence on Brain Vascular Reserve and Flow Efficiency

Keyeux

Ochrymowiczbemelmans

Charlier

1995

J Cereb Blood Flow Metab

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Summary: This study was undertaken to investigate the mechanisms of CBF increase as induced by hypercapnia. It was achieved in anesthetized rats by determining total cerebral blood volume (TCBV), parenchymal blood (CBV), plasma (CPV), erythrocyte (CEV) volumes and cerebral hematocrit (CHct) as well as CBF at about 40, 60, and 80 mm Hg Pac0 2 • TCBV was measured by a non invasive blood dilution method using [99mTc)pertechne tate. CBV, CPV, and CEV were measured on isolated brain by 1 2 5I_serum albumin and 5ICr-erythrocytes. CBF was measured by both ['31I114Cjiodoantipyrine and 57CO_ microsphere extractions. The extraparenchymal blood volume (ECBV) was evaluated by subtracting CBV from TCBV. Under normocapnia, ECBV was 2.8 times larger than CBV. Under moderate hypercapnia; ECBV in creased by 44%, CBV was not modified, and CBF inBlood supply to the brain ongmates from the aorta and is provided by the two internal carotid arteries and the two vertebral arteries. The blood entering the skull is then distributed between three pairs of cerebral arteries, of which terminal branches are interconnected through arterioarterial pial anastomoses (Van den Bergh and Van der Eecken, 1968). These interconnecting series of small distributing arteries branch over the surface of the brain, sending off arteries and arterioles that penetrate the brain to varying depths before divid-

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Section: Cerebral Blood Volumementioning

confidence: 63%

mentioning

confidence: 99%

Induced Response to Hypercapnia in the Two-Compartment Total Cerebral Blood Volume: Influence on Brain Vascular Reserve and Flow Efficiency

Keyeux

Ochrymowiczbemelmans

Charlier

1995

J Cereb Blood Flow Metab

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“…1-4 and Table 1). We conjecture, based on comparative studies of pial vasculature (38), that a similar topology is found in higher mammals.…”

Section: Discussionmentioning

confidence: 99%

Topological basis for the robust distribution of blood to rodent neocortex

Blinder¹,

Shih²,

Rafie³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

165

224

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The maintenance of robust blood flow to the brain is crucial to the health of brain tissue. We examined the pial network of the middle cerebral artery, which distributes blood from the cerebral arteries to the penetrating arterioles that source neocortical microvasculature, to characterize how vascular topology may support such robustness. For both mice and rats, two features dominate the topology. First, interconnected loops span the entire territory sourced by the middle cerebral artery. Although the loops comprise <10% of all branches, they maintain the overall connectivity of the network after multiple breaks. Second, >80% of offshoots from the loops are stubs that end in a single penetrating arteriole, as opposed to trees with multiple penetrating arterioles. We hypothesize that the loops and stubs protect blood flow to the parenchyma from an occlusion in a surface vessel. To test this, we assayed the viability of tissue that was sourced by an individual penetrating arteriole following occlusion of a proximal branch in the surface loop. We observed that neurons remained healthy, even when occlusion led to a reduction in the local blood flow. In contrast, direct blockage of a single penetrating arteriole invariably led to neuronal death and formation of a cyst. Our results show that the surface vasculature functions as a grid for the robust allocation of blood in the event of vascular dysfunction. The combined results of the present and prior studies imply that the pial network reallocates blood in response to changing metabolic needs.anastomoses | imaging | networks | stroke | vasculature

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“…The optical depth of the mea surement in the capillary region is unknown. How ever, because the pial arterioles and venules pene trate tangentially into the cortex (Mchedlishvili and Kuridze, 1984), the reflected light originating from these thick vessels may not include the spectrum of the capillary region.…”

Section: Evaluation Of Present Systemmentioning

confidence: 99%

Intravital Microreflectometry of Individual Pial Vessels and Capillary Region of Rat

Watanabe

Harada

Kosaka

et al. 1994

J Cereb Blood Flow Metab

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Summary: A microscopic reflectance spectrophotometer was constructed to obtain the spectra of single pial ves sels and of a region containing only capillaries (capillary region). The difference in the oxygen saturation (S02) of hemoglobin between the regional arteriole and venule [R(A -V)] and that between the regional arteriole or capillaries [R(A -C)] were calculated. The reduction of cytochrome aa3 was also estimated in the capillary re gion. This method was applied to the brain surface of spontaneously breathing rats subjected to hypoxic and anemic hypoxia. On decreasing the inhaled O2 from 100 to 15%, elevation of R(A -V) and R(A -C) with slight arteriolar dilatation (though statistically not significant) was observed. Below 10% O2 (especially at 4 and 3% O2), Optical techniques provide valuable information for the study of tissue oxygen metabolism (Chance, 1991). The advantages of such methods include a capability of continuous monitoring in living ani mals with minimal damage to the tissue. Therefore, many optical methods have been developed, e.g., determination of the redox state of NADH by ultra violet fluorometry (Chance, 1954) and monitoring of the O2 saturation of flowing blood cells and/or the redox state of cytochrome aa3 by visible (Millikan, 1942; Sato et aI., 1979; Seiyama et aI., 1991) and infrared (Jobsis, 1977; Hazeki and Tamura, 1988) spectroscopy.Macroscopic reflectance spectroscopy measures the degree of oxygenation in blood and tissue. Thus, it has been conventionally used for studying Received June 24, 1992; final revision received April 29, 1993; accepted May 4, 1993. Address correspondence and reprint requests to Dr. T. Shiga at Department of Physiology, Medical School, Osaka Univer sity, 2-2 Yamadaoka, Suita, Osaka 565, Japan.Abbreviations used: Hb, hemoglobin; Ht, hematocrit; OD, op tical density; R(A -V), regional arteriole-venule difference in O2 saturation; R(A -C), regional arteriole-capillary difference in O2 saturation. 75the R(A -V) and R(A -C) decreased in spite of signif icant arteriolar dilatation with progressive reduction of cytochrome aa3, indicating suppression of oxygen trans port to mitochondria. In the case of hemodilution down to 37% hematocrit (Ht), elevation of R(A -V) and R(A -C) occurred with a slight tendency toward arteriolar di latation. Below 32% Ht, the R(A -V) decreased but the R(A -C) remained steady, while reduction of cy tochrome aa3 progressed. Altogether, the S02 in the cap illary region decreased and the reduction of cytochrome aa3 progressed with the decline of arteriolar O2 supply in both hypoxic and anemic hypoxia.

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The Modular Organization of the Pial Arterial System in Phylogeny

Cited by 48 publications

References 13 publications

Induced Response to Hypercapnia in the Two-Compartment Total Cerebral Blood Volume: Influence on Brain Vascular Reserve and Flow Efficiency

Induced Response to Hypercapnia in the Two-Compartment Total Cerebral Blood Volume: Influence on Brain Vascular Reserve and Flow Efficiency

Topological basis for the robust distribution of blood to rodent neocortex

Intravital Microreflectometry of Individual Pial Vessels and Capillary Region of Rat

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