Coupling between the blood lactate-to-pyruvate ratio and MCA Vmean at the onset of exercise in humans

2009 ◽  
Vol 107 (6) ◽  
pp. 1799-1805 ◽  
Author(s):  
Peter Rasmussen ◽  
Camilla A. Madsen ◽  
Henning B. Nielsen ◽  
Morten Zaar ◽  
Albert Gjedde ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Tissue ◽  
Oxygen Tension ◽  
Redox State ◽  
Mean Flow ◽  
Cerebral Capillary ◽  
Calculated Average ◽  
Exercise In Humans ◽  
Pyruvate Ratio

Activation-induced increase in cerebral blood flow is coupled to enhanced metabolic activity, maybe with brain tissue redox state and oxygen tension as key modulators. To evaluate this hypothesis at the onset of exercise in humans, blood was sampled at 0.1 to 0.2 Hz from the radial artery and right internal jugular vein, while middle cerebral artery mean flow velocity (MCA Vmean) was recorded. Both the arterial and venous lactate-to-pyruvate ratio increased after 10 s ( P < 0.05), and the arterial ratio remained slightly higher than the venous ( P < 0.05). The calculated average cerebral capillary oxygen tension decreased by 2.7 mmHg after 5 s ( P < 0.05), while MCA Vmean increased only after 30 s. Furthermore, there was an unaccounted cerebral carbohydrate uptake relative to the uptake of oxygen that became significant 50 s after the onset of exercise. These findings support brain tissue redox state and oxygenation as potential modulators of an increase in cerebral blood flow at the onset of exercise.

scholarly journals Local Cerebral Blood Flow and Glucose Consumption of Rats with Experimental Gliomas

1982 ◽  
Vol 2 (1) ◽  
pp. 25-32 ◽  
Author(s):  
K.-A. Hossmann ◽  
I. Niebuhr ◽  
M. Tamura
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Tumors ◽  
Brain Tissue ◽  
Glucose Utilization ◽  
Cell Clone ◽  
Tumor Development ◽  
Glucose Consumption ◽  
Contralateral Side ◽  
Opposite Hemisphere

Experimental brain tumors were produced in rats by intracerebral implantation of a neoplastic glial cell clone. Within 2–6 weeks, spherical brain tumors developed at the implantation site with a mean diameter of 6 mm. Local blood flow and local glucose utilization were measured under light barbiturate anesthesia by quantitative autoradiography in the tumor and peritumoral brain tissue. In solid parts of the tumor, blood flow was 57.8 ± 2.0 ml/100 g/min (mean ± SE), and glucose utilization was 87.2 ± 5.8 μmol/100 g/min, respectively. In necrotic regions, flow and glucose utilization were zero. In peritumoral brain tissue of the ipsilateral hemisphere blood flow was reduced by 13–23%, as compared to homologous regions of the opposite side, the greatest decrease being recorded in the ipsilateral thalamus. Flow in the opposite hemisphere was of the same order of magnitude as in normal control rats. Glucose consumption, in contrast, was distinctly reduced in both hemispheres: in the cortex and putamen, it was 40–50% lower than in normal controls. The following conclusions are drawn: (1) during tumor development the high glucose consumption in the tumor tissue is not coupled to an equal increase in blood flow; (2) peritumoral cerebral blood flow decreases on the ipsilateral but not on the contralateral side, and (3) the metabolic rate of glucose is distinctly inhibited in both hemispheres of tumor-bearing animals. The dissociation between blood flow and metabolism suggests that metabolic inhibition is not the consequence of a diaschitic depression of functional activity.

Abstract TP446: Independent Measures of Cerebral Blood Flow in Asymptomatic Carotid Artery Disease.

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
Randolph S Marshall ◽  
MaryKay Pavol ◽  
Ken Cheung ◽  
Isabelle Strom ◽  
Kevin Slane ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Carotid Artery ◽  
Function Analysis ◽  
Flow Regulation ◽  
Critical Element ◽  
Mean Flow ◽  
Blood Flow Regulation ◽  
Hemodynamic State ◽  
Transfer Function Analysis

Background: Cerebral blood flow (CBF) regulation is a critical element in cerebrovascular pathophysiology, particularly in large vessel disease. Different methods to assess hemodynamics may represent different aspects of blood flow regulation, however, uniquely affecting outcomes and management. We examined 4 different blood-flow related measures in patients with high-grade unilateral carotid disease, assessing asymmetry between the occluded vs non-occluded side, and the correlations among the measures. Methods: Thirty-three patients (age 50-93, 19M) with unilateral 80-100% ICA occlusion but no stroke underwent: 1) quantitative resting CBF using continuous arterial spin labeling (CASL) MRI, 2) mean flow velocity (MFV) in both middle cerebral arteries (MCAs) by transcranial Doppler, 3). Vasomotor reactivity (VMR) in response to 2 minutes of 5% CO2 inhalation, and 4) Dynamic cerebral autoregulation (DCA) using continuous insonation of both MCAs for 10 minutes at depth 56mm with a standard head frame. Phase shift (PS) between spontaneous oscillations in blood pressure (measured with finger photoplethysmography) and MCA MFV at frequencies .06-.12 Hz was calculated for each hemisphere using transfer function analysis. Lower PS indicated worse autoregulation. Paired T-tests and Pearson correlations were used to look for side-to-side differences within each measure, and correlations between measures (SPSS v.22). Results: CASL CBF (p=.001), MFV (p<.001), VMR (p=.008), and DCA (p=.047) all showed significantly lower values on the occluded side. The 4 measures were independent of each other on correlation analysis, even when controlling for age and anterior circle of Willis collateral (correlation coefficients all <0.40, p-values >0.09). Conclusions: These 4 measures showed high sensitivity to the occluded carotid artery, but appear to represent independent aspects of cerebral blood flow (CASL: resting gray matter CBF; MFV: whole-hemisphere CBF; VMR: cerebrovascular reserve, and DCA: homeostatic blood flow regulation) suggesting that any given measure only partially characterizes hemodynamic state. Further investigation will use these 4 measures to predict outcomes including vascular cognitive impairment.

Abstract P531: Cerebral Blood Flow Analysis Using Flow Wire Measurements and CFD Analysis

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Aichi Chien ◽  
Huy Dinh ◽  
Viktor Szeder ◽  
Fernando Vinuela
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Flow Velocity ◽  
Cfd Simulation ◽  
Cfd Analysis ◽  
Flow Data ◽  
Velocity Data ◽  
Mean Flow ◽  
Good Agreement ◽  
Cerebral Vascular

Introduction: Clinical reports show that cerebral blood flow conditions are indicative of cerebral vascular disease. While methods for characterizing cerebral vascular flow have been extensively reported in the past, comparative analyses between direct flow measurements (DM) and computational flow dynamic (CFD) analysis remain limited. We hypothesize that flow data can be reliably measured both directly and through CFD in normal vessels. Methods: A left heart replicator was used as a realistic cardiac pump which maintained systolic pressure at 120 mmHg and diastolic pressure at 80 mmHg. A stenotic model with 50% stenosis for the ICA was connected to the replicator. A ComboWire was used for DM and recorded flow pressure and velocity. CFD was used to study flow. Results: In areas at the proximal end of the stenosis, the pressure and flow velocity derived from DM and CFD were in good agreement. At the end of systole and diastole, DM pressure were 145.42 mmHg and 73.53 mmHg, respectively. CFD simulation for the same system obtained the pressure at the end of systole and diastole of 147.16 mmHg and 74.64 mmHg, respectively. The velocity data collected from DM was at 15.40 cm/s and 7.74 cm/s for systolic flow and mean flow velocity. CFD measured flow was 17.85 cm/s and 11.37 cm/s, respectively. In areas at the distal end of the stenosis, pressure data showed good agreement between DM and CFD analysis. The DM were 138 and 70.81 mmHg at the end of systole and diastole, respectively; CFD simulation yielded 145.95 and 74.51 mmHg, respectively. Variations in the velocity data were observed at this location (Fig, pink arrows). Conclusion: DM of pressure showed good agreement with CFD simulation in all areas of the vessel. DM of velocity using the flow wire were highly affected by location of the measurement. CFD analysis can provide more consistent flow data for flow information collection along the vasculature.

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