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  • 1
    Electronic Resource
    Electronic Resource
    Transport of Lead-203 at the Blood-Brain Barrier During Short Cerebrovascular Perfusion with Saline in the Rat (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Lead transport at the blood-brain barrier has been studied by short (〈 1.5 min) vascular perfusion of one cerebral hemisphere of the rat with a buffered physiological salt solution at pH 7.4 without calcium, magnesium, or bicarbonate and containing 203Pb-labelled lead chloride. In the absence of complexing agents, 203Pb uptake was rapid, giving a space of 9.7 ml/100 g of wet frontal cortex at 1 min. Lead-203 influx was linear with lead concentration up to 4 μM. Five percent albumin, 200 μM cysteine, or 1 μM EDTA almost abolished 203Pb uptake. Lead-203 entry into brain was uninfluenced by varying the calcium concentration or by magnesium or the calcium blocker methoxyverapamil. Similarly, 1 μM bicarbonate or 50 μM 4,4′-diisothiocyanostilbene-2,2′-disulphonic acid was without effect. Increasing the potassium concentration reduced 203Pb uptake. Vanadate at 2 μM, 2 μM carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (a metabolic uncoupler), or 2 μM stannic chloride all markedly enhanced lead entry into brain, as did a more alkaline pH (7.80). In conclusion, there is a mechanism allowing rapid passive transport of 203Pb at the brain endothelium, perhaps as PbOH+. Lead uptake into brain via this system is probably made less important by active transport of lead back into the capillary lumen by the calcium-ATP-dependent pump.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb02337.x
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  • 2
    Electronic Resource
    Electronic Resource
    Transport of Zinc-65 at the Blood-Brain Barrier During Short Cerebrovascular Perfusion in the Rat: Its Enhancement by Histidine (1994)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 62 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Zinc-65 transport into different regions of rat brain has been measured during short vascular perfusion of one cerebral hemisphere with an oxygenated HEPES-containing physiological saline at pH 7.40. The [Zn2+] was buffered with either bovine serum albumin or histidine. In each case uptake was linear with time up to 90 s. 65Zn flux into brain in the presence of albumin followed Michaelis-Menten kinetics and for parietal cortex had a Km of 16 nM and a Vmax of 44 nmol/kg/min. Increasing concentrations of l-histidine enhanced 65Zn flux into brain at [Zn2+] values between 1 and 1,000 nM. The combined effect of [histidine] and [Zn2+] was best accounted for by a function of [ZnHis+], i.e., flux = 64.4 · [ZnHis+]/(390 + [ZnHis+]) + 0.00378 · [ZnHis+], with concentrations being nanomolar. d-Histidine had an influence similar to that of l-histidine. 65Zn flux in the presence of 100 µMl-histidine was not affected by either 500 µMl-arginine or 500 µMl-phenylalanine. The results indicate specific transport of Zn2+ across the plasma membranes of brain endothelium. The enhancement due to histidine has been attributed to diffusion of ZnHis+ across unstirred layers “ferrying” zinc to and from transport sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.62020665.x
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  • 3
    Electronic Resource
    Electronic Resource
    Rate of 59Fe Uptake into Brain and Cerebrospinal Fluid and the Influence Thereon of Antibodies Against the Transferrin Receptor (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 60 (1993), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Uptake of 59Fe from blood into brains of anaesthetized rats and mice has been studied by intravenous infusion of [59Fe]ferrous ascorbate or of 59Fe-transferrin, the results not being significantly different. Uptakes in the rat were linear with time, but increased at longer times in the mouse. Transfer constants, Kin (in ml/g/h × 103), for cerebral hemispheres were 5.2 in the adult rat and 5.6 in the mouse. These Kin values corresponded to 59Fe influxes of 145 and 322 pmol/g/h, respectively. 59Fe uptake into the mouse brain occurred in the following order: cerebellum 〉 brainstem 〉 frontal cerebral cortex 〉 parietal cortex 〉 occipital cortex 〉 hippocampus 〉 caudate nucleus. In genetically hypotransferrinaemic mice, 59Fe uptake into brain was 80–95 times greater than in To strain mice. Pretreatment of young rats and mice with monoclonal antibodies to transferrin receptors, i.e., the anti-rat immunoglobulin G OX 26 and the anti-mouse immunoglobulin M RI7 208, inhibited 59Fe uptake into spleen by 94% and 98%, respectively, indicating saturation of receptors. The antibodies reduced 59Fe uptake into rat brain by 35–60% and that into mouse brain by 65–85%. Although a major portion of iron transport across the blood-brain barrier is normally transferrin-mediated, non-transferrin-bound iron readily crosses it at low serum transferrin levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1993.tb05828.x
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  • 4
    Electronic Resource
    Electronic Resource
    Transport of Iron in the Blood-Brain-Cerebrospinal Fluid System (1997)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 69 (1997), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Iron is an important constituent in brain and, in certain regions, e.g., the basal nuclei, reaches concentrations equivalent to those in liver. It has a role in electron transfer and is a cofactor for certain enzymes, including those involved in catecholamine and myelin synthesis. Iron in CSF is likely to be representative of that in interstitial fluid of brain. Transferrin in CSF is fully saturated, and the excess iron may be loosely bound as Fe(II). Brain iron is regulated in iron depletion, suggesting a role for the blood-brain barrier (BBB). Iron crosses the luminal membrane of the capillary endothelium by receptor-mediated endocytosis of ferric transferrin. This results in an initial linear uptake of radioactive iron into brain at an average rate relative to serum of about 3.3 × 10−3 ml·g of brain−1·h−1 in the adult rat. This corresponds to about 80 nmol·kg−1·h−1. Much higher rates occur in the postnatal rat. These increase during the first 15 days of life and decline thereafter. Within the endothelium, most of the iron is separated from transferrin, presumably by the general mechanism of acidification within the endosome. Iron appears to be absorbed from the vesicular system into cytoplasm and transported across the abluminal plasma membrane into interstitial fluid as one or more species of low molecular weight. There is some evidence that ionic Fe(II) is involved. Certainly Fe(II) ions presented on the luminal side rapidly cross the complete BBB, i.e., luminal and abluminal membranes. Within interstitial fluid, transported iron will bind with any unsaturated transferrin synthesized or transported into the brain-CSF system. Oligodendrocytes are one site of synthesis. From interstitial fluid, ferric transferrin is taken up by neurones and glial cells by the usual receptor-mediated endocytosis. Calculations of the amount of iron leaving the system with the bulk flow of CSF indicate that most iron entering brain across the capillary endothelium finally leaves the system with the bulk outflow of CSF through arachnoid villi and other channels. A system in which influx of iron into brain is by regulated receptor-mediated transport and in which efflux is by bulk flow is ideal for homeostasis of brain iron.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1997.69020443.x
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  • 5
    Electronic Resource
    Electronic Resource
    Stimulation of the Sodium Pump in the Red Blood Cell by Lithium and Potassium (1972)
    [s.l.] : Nature Publishing Group
    Nature 239 (1972), S. 399-401 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A deficit in sodium transport has been reported in some patients with depressive illness1 ~3, and the administration of lithium has been observed to reduce intracellular sodium as measured by the 24Na and 82Br spaces4'5. A similar reduction in the intracellular sodium concentration in rabbits ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/239399a0
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  • 6
    Electronic Resource
    Electronic Resource
    Brain Endothelium and Interstitium as Sites for Effects of Lead (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 529 (1988), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1988.tb51414.x
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  • 7
    Electronic Resource
    Electronic Resource
    Introductory Remarks: The Developing Experimental Approach to the Idea of a Blood–Brain Barrier (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 481 (1986), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1986.tb27146.x
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  • 8
    Electronic Resource
    Electronic Resource
    Rate of Uptake of Lead-203 into Brain and Other Soft Tissues of the Rat at Constant Radiotracer Levels in Plasma (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 481 (1986), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1986.tb27147.x
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  • 9
    Electronic Resource
    Electronic Resource
    The distribution of 125I-metrizamide and 125I-diatrizoate between blood, brain and cerebrospinal fluid in the rabbit (1980)
    Springer
    Neuroradiology 19 (1980), S. 171-180 
    Details
    ISSN: 1432-1920
    Keywords: Metrizamide ; Diatrizoate ; Blood-brain barrier ; Diffusion in brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The entry of 125I-metrizamide and of 125I-diatrizoate from blood into brain has been studied in rabbits. The blood-brain barrier is very tight to both molecules, all cerebral regions having spaces between 0.5 and 2% after maintenance of constant blood levels for 4 h. In extraneural tissues both compounds appear to distribute in extracellular fluid except for accumulation of metrizamide by the liver and perhaps the small intestine. Profiles of radioactivity through cerebral gray matter have been obtained following ventriculocisternal perfusion of artificial cerebrospinal fluid containing 125I-metrizamide. The nature of these profiles and their behavior with time suggest that metrizamide passes through gray matter by simple diffusion, that it is largely distributed in the extracellular fluid and that back movement across the blood-brain barrier is small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00376705
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