Water extraction fraction and permeability-surface product after intravenous injection in rats.

Takagi, Shigeharu; Ehara, Kazumasa; Finn, Ronald D.

doi:10.1161/01.str.18.1.177

Cited by 19 publications

(24 citation statements)

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“…Whether primates differ from mammals in general is not known, because we Values are obtained from the literature (L) and the present study (P). Mean of four studies (Bailey et al, 2004;Hasegawa et al, 2010;Karbowski, 2007;Tajima et al, 1993); 11 Mean of four studies (Nakao et al, 2001;Ohno et al, 1979;Sakurada et al, 1978;Takagi et al, 1987); 12 Sato et al, 1999; 13 Macgowan et al, 2015;14 Christopher Macgowan (personal communication); ICA lumen radius from three mice; Foramen radius calculated from ICA lumen radius×1.4 (see note 6). are unable to gauge brain perfusion in other groups with the technique of this study.…”

Section: Discussionmentioning

confidence: 99%

“…We estimated the scaling of shear stress for the internal carotid artery from measured data from 70 kg humans (this study) and 375 g rats (Cai et al, 2012) using the shear stress equation and literature values. Blood flow rate in one internal carotid artery is taken as 3.83 cm 3 s −1 in humans (Boysen et al, 1970) and 0.028 cm 3 s −1 in rats (mean of four studies: Nakao et al, 2001;Ohno et al, 1979;Sakurada et al, 1978;Takagi et al, 1987). ICA lumen radius is taken as 0.221 cm in humans (mean of three studies: Kane et al, 1996;Krejza et al, 2006;Porsche et al, 2002) and 0.0304 in rats (Cai et al, 2012).…”

Section: Shear Stress (τ)mentioning

confidence: 99%

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Scaling of cerebral blood perfusion in primates and marsupials

Seymour

Angove

Snelling

et al. 2015

Journal of Experimental Biology

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The evolution of primates involved increasing body size, brain size and presumably cognitive ability. Cognition is related to neural activity, metabolic rate and rate of blood flow to the cerebral cortex. These parameters are difficult to quantify in living animals. This study shows that it is possible to determine the rate of cortical brain perfusion from the size of the internal carotid artery foramina in skulls of certain mammals, including haplorrhine primates and diprotodont marsupials. We quantify combined blood flow rate in both internal carotid arteries as a proxy of brain metabolism in 34 species of haplorrhine primates (0.116-145 kg body mass) and compare it to the same analysis for 19 species of diprotodont marsupials (0.014-46 kg). Brain volume is related to body mass by essentially the same exponent of 0.70 in both groups. Flow rate increases with haplorrhine brain volume to the 0.95 power, which is significantly higher than the exponent (0.75) expected for most organs according to 'Kleiber's Law'. By comparison, the exponent is 0.73 in marsupials. Thus, the brain perfusion rate increases with body size and brain size much faster in primates than in marsupials. The trajectory of cerebral perfusion in primates is set by the phylogenetically older groups (New and Old World monkeys, lesser apes) and the phylogenetically younger groups (great apes, including humans) fall near the line, with the highest perfusion. This may be associated with disproportionate increases in cortical surface area and mental capacity in the highly social, larger primates.

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Section: Discussionmentioning

confidence: 99%

Section: Shear Stress (τ)mentioning

confidence: 99%

Scaling of cerebral blood perfusion in primates and marsupials

Seymour

Angove

Snelling

et al. 2015

Journal of Experimental Biology

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“…This hypothesis led to the following simplified equation:

C B F = \frac{λ \cdot Δ M \cdot exp (|, D \cdot A T T)}{2 α \cdot M_{0}^{t}} {([]|, \frac{1 - e^{- J t^{'}}}{J} + A \cdot (|, \frac{J - C + C \cdot e^{- J t^{'}} - J \cdot e^{- C t^{'}}}{J \cdot C \cdot (|, J - C)}))}^{- 1} for A T T \leq t \leq A T T + τ

C B F = \frac{λ \cdot Δ M \cdot exp (|, D \cdot A T T)}{2 α \cdot M_{0}^{t}} {([]|, (|, \frac{1}{J} + \frac{A}{J (|, C - J)}) (|, e^{- J τ} - 1) e^{- J t^{'}} - \frac{A \cdot e^{- C t^{'}}}{C (|, C - J)} (|, e^{C τ} - 1))}^{- 1} normalf normalo normalr t \geq A T T + τ,

where t ′ = t‐ATT and t = τ + ω. Because ATT was 233 ms for the cortex and 177 ms for the striatum, according to Thomas et al , we used Equation for the cortex and Equation for the striatum, where A = PS/v bw , C = 1/T 1e , D = 1/T 1b , and J = A + D, with PS as the water permeability surface area product [PS = 155 mL · 100 g −1 · min −1 , ], T 1e as the T 1 of extravascular water and may be approximated by

T_{1}^{t}

, and v bw as the blood water volume fraction in the voxel, which correspond to 70% of the total blood volume fraction . For the total blood vo...…”

Section: Methodsmentioning

confidence: 99%

Impact of tissue T₁on perfusion measurement with arterial spin labeling

et al. 2016

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A low dose of Mn reduces the tissue T without modifying CBF. Heterogeneous T impacts the ASL estimate of CBF in a region-dependent way. In animals, and when T modifications exceed the accuracy with which the tissue T can be determined, an estimate of tissue T should be obtained when quantifying CBF with an ASL technique. Magn Reson Med 77:1656-1664, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

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“…Measurements with tritiated water have shown that 70–90% of the water molecules in the blood perfusing the brain cross the blood–brain barrier and enter the brain tissues in a single pass ([chapter 4 in 16], [36–42]). If cerebral blood flow is 800 ml min −1 [43] then brain blood water flow, the water flow along the capillaries, is perhaps 0.85 × 800 ml min −1 = 680 ml min −1 (the rest is made up of solutes such as haemoglobin).…”

Section: Transfers Of Water O2 Co2 and Major Nutrients Between Bloomentioning

confidence: 99%

Fluid and ion transfer across the blood–brain and blood–cerebrospinal fluid barriers; a comparative account of mechanisms and roles

Hladky

Barrand

2016

Fluids Barriers CNS

229

253

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The two major interfaces separating brain and blood have different primary roles. The choroid plexuses secrete cerebrospinal fluid into the ventricles, accounting for most net fluid entry to the brain. Aquaporin, AQP1, allows water transfer across the apical surface of the choroid epithelium; another protein, perhaps GLUT1, is important on the basolateral surface. Fluid secretion is driven by apical Na+-pumps. K+ secretion occurs via net paracellular influx through relatively leaky tight junctions partially offset by transcellular efflux. The blood–brain barrier lining brain microvasculature, allows passage of O2, CO2, and glucose as required for brain cell metabolism. Because of high resistance tight junctions between microvascular endothelial cells transport of most polar solutes is greatly restricted. Because solute permeability is low, hydrostatic pressure differences cannot account for net fluid movement; however, water permeability is sufficient for fluid secretion with water following net solute transport. The endothelial cells have ion transporters that, if appropriately arranged, could support fluid secretion. Evidence favours a rate smaller than, but not much smaller than, that of the choroid plexuses. At the blood–brain barrier Na+ tracer influx into the brain substantially exceeds any possible net flux. The tracer flux may occur primarily by a paracellular route. The blood–brain barrier is the most important interface for maintaining interstitial fluid (ISF) K+ concentration within tight limits. This is most likely because Na+-pumps vary the rate at which K+ is transported out of ISF in response to small changes in K+ concentration. There is also evidence for functional regulation of K+ transporters with chronic changes in plasma concentration. The blood–brain barrier is also important in regulating HCO3 − and pH in ISF: the principles of this regulation are reviewed. Whether the rate of blood–brain barrier HCO3 − transport is slow or fast is discussed critically: a slow transport rate comparable to those of other ions is favoured. In metabolic acidosis and alkalosis variations in HCO3 − concentration and pH are much smaller in ISF than in plasma whereas in respiratory acidosis variations in pHISF and pHplasma are similar. The key similarities and differences of the two interfaces are summarized.

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Water extraction fraction and permeability-surface product after intravenous injection in rats.

Cited by 19 publications

References 13 publications

Scaling of cerebral blood perfusion in primates and marsupials

Scaling of cerebral blood perfusion in primates and marsupials

Impact of tissue T₁on perfusion measurement with arterial spin labeling

Fluid and ion transfer across the blood–brain and blood–cerebrospinal fluid barriers; a comparative account of mechanisms and roles

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Water extraction fraction and permeability-surface product after intravenous injection in rats.

Cited by 19 publications

References 13 publications

Scaling of cerebral blood perfusion in primates and marsupials

Scaling of cerebral blood perfusion in primates and marsupials

Impact of tissue T1on perfusion measurement with arterial spin labeling

Fluid and ion transfer across the blood–brain and blood–cerebrospinal fluid barriers; a comparative account of mechanisms and roles

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Product

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Impact of tissue T₁on perfusion measurement with arterial spin labeling