scholarly journals Precapillary sphincters control cerebral blood flow

2019 ◽  
Author(s):  
Søren Grubb ◽  
Changsi Cai ◽  
Bjørn O. Hald ◽  
Lila Khennouf ◽  
Jonas Fordsmann ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Functional Neuroimaging ◽  
Smooth Muscle Actin ◽  
Cell Activity ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen Level ◽  
Brain Capillary ◽  
Blood Flow Control ◽  
Precapillary Sphincter

AbstractActive nerve cells produce and release vasodilators that increase their energy supply by dilating local blood vessels, a mechanism termed neurovascular coupling, which is the basis of the BOLD (blood-oxygen-level-dependent) functional neuroimaging signals. We here reveal a unique mechanism for cerebral blood flow control, a precapillary sphincter at the transition between the penetrating arteriole and the first capillary that links blood flow in capillaries to the arteriolar inflow. Large NG2-positive cells, containing smooth muscle actin, encircle the sphincters and rises in nerve cell activity cause astrocyte and neuronal Ca2+ rises that correlate to dilation and shortening of the sphincter concomitant with substantial increases in the RBC flux. Global ischemia and cortical spreading depolarization constrict sphincters and cause vascular trapping of blood cells. These results reveal precapillary sphincters as bottlenecks for brain capillary blood flow.

scholarly journals BOLD and Perfusion Response to Finger-Thumb Apposition after Acetazolamide Administration: Differential Relationship to Global Perfusion

2003 ◽  
Vol 23 (7) ◽  
pp. 829-837 ◽  
Author(s):  
Gregory G. Brown ◽  
Lisa T. Eyler Zorrilla ◽  
Bassem Georgy ◽  
Sandra S. Kindermann ◽  
Eric C. Wong ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Blood Oxygen Level Dependent ◽  
Bold Response ◽  
Blood Oxygen Level ◽  
Individual Subject ◽  
Cerebrovascular Reserve ◽  
Global Cerebral Blood Flow ◽  
Hand Area ◽  
Cortical Perfusion

The authors studied the effects of altering global cerebral blood flow on both blood oxygen level–dependent (BOLD) response and perfusion response to finger-thumb apposition. A PICORE/QUIPSS II protocol was used to collect interleaved BOLD-weighted and perfusion-weighted images on eight finger-thumb apposition trials. Subjects were studied on a drug-free day and on a day when acetazolamide was administered between the second and third trials. After acetazolamide administration, resting cortical perfusion increased an average of 20% from preadministration levels, whereas the BOLD response to finger-thumb apposition decreased by an average of 35% in the S1M1 hand area. Contrary to predictions from the exhausted cerebrovascular reserve hypothesis and the oxygen limitation model, an effect of acetazolamide on cerebral blood flow response in the S1M1 hand area was not observed. Across the acetazolamide trials, BOLD response was inversely correlated with resting cortical perfusion for individual subject data. These results suggest that resting perfusion affects the magnitude of the BOLD response and is thus an important confounding factor in fMRI studies, and that the physiologic systems that increase cerebral blood flow in response to acetazolamide administration and systems that increase cerebral blood flow in response to altered neural activity appear to have additive effects.

scholarly journals Interictal cortical hyperresponsiveness in migraine is directly related to the presence of aura

Cephalalgia ◽  
2013 ◽  
Vol 33 (6) ◽  
pp. 365-374 ◽  
Author(s):  
Ritobrato Datta ◽  
Geoffrey K Aguirre ◽  
Siyuan Hu ◽  
John A Detre ◽  
Brett Cucchiara
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Visual Stimulus ◽  
Visual Stimulation ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen Level ◽  
Visual Discomfort ◽  
Bold Fmri ◽  
Control Subjects ◽  
And Control

Objective The objective of this study was to compare the interictal cortical response to a visual stimulus between migraine with aura (MWA), migraine without aura (MwoA), and control subjects. Methods In a prospective case-control study, blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) was used to assess the response to a visual stimulus and arterial spin labeled perfusion MR to determine resting cerebral blood flow. A standardized questionnaire was used to assess interictal visual discomfort. Results Seventy-five subjects (25 MWA, 25 MwoA, and 25 controls) were studied. BOLD fMRI response to visual stimulation within primary visual cortex was greater in MWA (3.09 ± 0.15%) compared to MwoA (2.36 ± 0.13%, p = 0.0008) and control subjects (2.47 ± 0.11%, p = 0.002); responses were also greater in the lateral geniculate nuclei in MWA. No difference was found between MwoA and control groups. Whole brain analysis showed that increased activation in MWA was confined to the occipital pole. Regional resting cerebral blood flow did not differ between groups. MWA and MwoA subjects had significantly greater levels of interictal visual discomfort compared to controls ( p = 0.008 and p = 0.005, respectively), but this did not correlate with BOLD response. Conclusions Despite similar interictal symptoms of visual discomfort, only MWA subjects have cortical hyperresponsiveness to visual stimulus, suggesting a direct connection between cortical hyperresponsiveness and aura itself.

scholarly journals A critical role for the ATP-sensitive potassium channel subunit KIR6.1 in the control of cerebral blood flow

2018 ◽  
Vol 39 (10) ◽  
pp. 2089-2095 ◽  
Author(s):  
Patrick S Hosford ◽  
Isabel N Christie ◽  
Arun Niranjan ◽  
Qadeer Aziz ◽  
Naomi Anderson ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Potassium Channel ◽  
Cerebral Oxygenation ◽  
Critical Role ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen Level ◽  
Functional Changes ◽  
A Subunit ◽  
Brain Parenchymal

KIR6.1 (KCNJ8) is a subunit of ATP sensitive potassium channel (KATP) that plays an important role in the control of peripheral vascular tone and is highly expressed in brain contractile cells (vascular smooth muscle cells and pericytes). This study determined the effect of global deletion of the KIR6.1 subunit on cerebral blood flow, neurovascular coupling and cerebral oxygenation in mice. In KIR6.1 deficient mice resting cerebral blood flow and brain parenchymal partial pressure of oxygen ( PO2) were found to be markedly lower compared to that in their wildtype littermates. However, cortical blood oxygen level dependent responses triggered by visual stimuli were not affected in conditions of KIR6.1 deficiency. These data suggest that KATP channels containing KIR6.1 subunit are critically important for the maintenance of normal cerebral perfusion and parenchymal PO2 but play no significant role in the mechanisms underlying functional changes in brain blood flow.

scholarly journals Test-retest reliability of task-based and resting-state blood oxygen level dependence and cerebral blood flow measures

PLoS ONE ◽  
2018 ◽  
Vol 13 (11) ◽  
pp. e0206583 ◽  
Author(s):  
Štefan Holiga ◽  
Fabio Sambataro ◽  
Cécile Luzy ◽  
Gérard Greig ◽  
Neena Sarkar ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Resting State ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Blood Oxygen Level ◽  
Retest Reliability ◽  
Test Retest Reliability ◽  
Blood Oxygen Level Dependence

Parallel changes of blood flow and heterogeneity of capillary plasma perfusion in rat brains during hypocapnia

1996 ◽  
Vol 270 (4) ◽  
pp. H1441-H1445
Author(s):  
J. Vogel ◽  
R. Abounader ◽  
H. Schrock ◽  
K. Zeller ◽  
R. Duelli ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Coefficient Of Variation ◽  
Blue Dye ◽  
Capillary Perfusion ◽  
Brain Capillary ◽  
Arterial Pco2 ◽  
Transit Times ◽  
The Brain ◽  
Experimental Group

Plasma perfusion patterns were investigated in brain capillaries during decreased cerebral blood flow induced by hyperventilation. Anesthetized rats were decapitated 3-4 s after being given an intravenous bolus injection of Evans blue dye. the measured steep increase of the arterial dye concentration at this moment ensures that different capillary plasma transit times are reflected in different intracapillary dye concentrations. The observed heterogeneity of capillary plasma transit time was expressed as the coefficient of variation (means +/- SD) of the intracapillary dye concentrations. For comparison, cerebral blood flow was determined at comparable PCO2 values in a second experimental group. At arterial PCO2 values between 40 and 25 mmHg, the cerebral blood flow and the coefficient of variation of the intracapillary dye concentration decreased with decreasing PCO2, whereas at PCO2 values <25 mmHg cerebral blood flow and coefficient of variation did not correlate with the arterial PCO2. However, it cannot be excluded that the coefficient of variation of the intracapillary dye concentration increases between 25 and 14 mmHg and decreases between 14 and 10 mmHg. It is concluded that the reduction of cerebral blood flow measured during moderate hypocapnia is paralleled by a decreased heterogeneity of the brain capillary perfusion. During severe hypocapnia this relationship is lost, indicating a potential disturbance of the cerebral microcirculation.

scholarly journals Isn't functional neuroimaging all about Ca2+ signaling in astrocytes?

2015 ◽  
Vol 114 (3) ◽  
pp. 1353-1356 ◽  
Author(s):  
Mauro DiNuzzo
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Functional Neuroimaging ◽  
Local Cerebral Blood Flow ◽  
The Past ◽  
Cereb Blood Flow ◽  
Intracellular Ca ◽  
Flow Through ◽  
Experimental Findings ◽  
Paradigm Shifting

Extensive research over the past decades about the multifaceted roles of brain astrocytes led to the suggestion that the signals observed with functional neuroimaging might primarily reflect astrocytic rather than neuronal activity. The basis for this paradigm-shifting concept was the evidence for an involvement of astrocytes in the control of local cerebral blood flow through intracellular Ca2+ signaling. In this Neuro Forum, I discuss new important experimental findings obtained by Jego et al. (Jego P, Pacheco-Torres J, Araque A, Canals S. J Cereb Blood Flow Metab 34: 1599–1603, 2014) as well as other closely related studies published recently, prompting a dismissal of substantial astrocytic contribution in functional neuroimaging.

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