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  • 1
    Electronic Resource
    Electronic Resource
    Ionic lanthanum passage across cerebral endothelium exposed to hyperosmotic arabinose (1983)
    Springer
    Acta neuropathologica 60 (1983), S. 49-60 
    Details
    ISSN: 1432-0533
    Keywords: Blood-brain barrier ; Ionic lanthanum ; Tight Junctions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Hyperosmotic media infused into the cerebral circulation open the blood-brain barrier to protein and colloid. The mechanism whereby such substances cross the affected vessels is still disputed. We describe here the transendothelial route taken by ionic lanthanum (La3+), a small electron-dense tracer which, unlike colloidal lanthanum, can be administered to the living animal. In adult rats, 2.9 ml of hyperosmotic (1.4 M) arabinose was infused into the internal carotid artery as a 30-s bolus, followed by 5 mM LaCl3. To find the extravasated La3+, which is invisible by light microscopy, horseradish peroxidase (HRP) was injected simultaneously into the femoral vein. The hyperosmotic treatment resulted in exudation of both HRP and La3+ primarily around cerebral arterioles. The La3+ crossed arterioles through successive tight junctions between endothelial cells. Although the tight junctions were not discernibly opened, they must have become permeable because the extracellular pools between successive tight junctions were penetrated by the La3+. These pools are normally inaccessible to La3+. Luminal and abluminal pits and cytoplasmic vesicles, some of them containing La3+, formed intraendothelial clusters. Their role, if any, in the transfer of ion remains remains uncertain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685347
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  • 2
    Electronic Resource
    Electronic Resource
    The blood-brain barrier to horseradish peroxidase at the onset of bicuculline-induced seizures in hypothalamus, pallidum, hippocampus, and other selected regions of the rabbit (1986)
    Springer
    Acta neuropathologica 69 (1986), S. 1-16 
    Details
    ISSN: 1432-0533
    Keywords: Blood-brain barrier ; Epileptic seizures ; Pinocytosis ; Hypothalamus ; Pallidum ; Hippocampus ; Septum ; Thalamus ; Periaque-ductal gray ; Cerebellar cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rabbits were subjected to bicuculline-induced generalized seizures of 15-min duration to elucidate the mechanism by which the macromolecule horseradish peroxidase (HRP) traverses the blood-brain barrier (BBB) in specific brain areas. Transendothelial pinocytosis at the level of arterioles was the main route of passage. In addition, in thalamus and hippocampus pinocytotic vesicles were observed in capillaries. In thalamus, hypothalamus and septum vesicles in the endothelium of venules were also present. Repeatedly, pinocytotic vesicles were ejecting their content into the interendothelial clefts, so that the presence of HRP reaction product between adjacent tight junctions cannot be considered a conclusive evidence for their opening. The HRP, which had reached the neuropil due to the seizure-evoked BBB opening, accumulated in the interstitial spaces and penetrated the synaptic cleft. Uptake of the tracer in vesicular form into presynaptic boutons, presumably excitatory ones as diagnosed by their ultrastructural features, was observed in all brain regions. The uptake was rare in septum, periaqueductal gray, hypothalamus, and cerebellar cortex; frequent in pallidum, hippocampus, and medulla oblongata; and very intense in thalamus. Uptake in postsynaptic dendrites was present mostly in the vicinity of boutons. Incorporation into glial processes was rare and confined to perivascular astrocytes. It is suggested, that HRP traverses the BBB by regionally selective, transmitter-controlled pinocytotic transport and that the neuronal uptake of the foreign protein is at least partially dependent on the involvement of synapses of particular brain regions in the paroxysmal activity during the generalized seizures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00687032
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  • 3
    Electronic Resource
    Electronic Resource
    Role of extracellular proteins in the dynamics of vasogenic brain edema (1985)
    Springer
    Acta neuropathologica 66 (1985), S. 3-11 
    Details
    ISSN: 1432-0533
    Keywords: Blood-brain barrier ; Serum proteins ; Water content ; Vasogenic brain edema
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationship between extravasation of protein into extracellular spaces of brain parenchyma and the water content of such regions were evaluated in an experimental model. In this model, a temporary opening of the blood-brain barrier (BBB) to proteins was produced without significant injury to the cellular elements of brain tissue. Rabbits were subjected to bolus injection of their own blood under 360–400 mm Hg pressure via the internal carotid artery. The opening of the barrier and its duration were evaluated with Evans blue (EB), horseradish peroxidase (HRP), and sodium fluorescein (NaFl) tracers. The water content of brain tissue was assessed by specific gravity (SG) measurements in 1-mm-diameter tissue samples. Quantitative evaluation of protein penetration into brain tissue was carried out using125I bovine serum albumin (BSA). The opening of the BBB to proteins persisted up to 9 h, whereas the barrier remained permeable to small molecular NaFl for 24 h. The SG measurements indicated in the areas of EB extravasation a progressive increment in water content up to 9 h, i.e., the duration of BBB opening to proteins. Following this, there was a progressive clearance of edema in spite of the BBB remaining open for NaFl for 24 h. Quantitative evaluations of125I-BSA and SG in the same tissue samples, supported by statistical analysis, indicated approximately linear relationship between albumin and water, implying a strong correlation between the development of vasogenic edema and extravasation of proteins into extracellular spaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698288
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  • 4
    Electronic Resource
    Electronic Resource
    Granule swelling in stimulated bovine adrenal chromaffin cells: regulation by internal granule pH (1994)
    Springer
    Cell & tissue research 279 (1994), S. 85-92 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Exocytosis ; Chromaffin cells ; Catecholamine secretion ; Membrane fusion ; Freeze substitution ; Cow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Adrenal medullary chromaffin cells secrete catecholamines through exocytosis of their intracellular chromaffin granules. Osmotic granule swelling has been implicated to play a role in the generation of membrane stress associated with the fusion of the granule membrane. However, controversy exists as to whether swelling occurs before or after the actual fusion event. Using morphometric methods we have determined the granule diameter distributions in rapidly frozen, freeze-substituted chromaffin cells. Our measurements show that intracellular chromaffin granules increase in size from an average of 234 nm to 274 nm or 277 nm in cells stimulated to secrete with nicotine or high external K+, respectively. Granule swelling occurs before the formation of membrane contact. Ammonium chloride, an agent which inhibits stimulated catecholamine secretion by approximately 50% by altering the intragranular pH, also inhibits granule swelling. In addition, ammonium chloride-treated secreting cells show more granule-plasma membrane contacts than untreated secreting cells. Sodium propionate induces granule swelling in the absence of secretagogue and has been shown to enhance nicotine- and high K+- induced catecholamine release. These results indicate that in adrenal chromaffin cells granule swelling is an essential step in exocytosis before fusion pore formation, and is related to the pH of the granule environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050264
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  • 5
    Electronic Resource
    Electronic Resource
    Granule swelling in stimulated bovine adrenal chromaffin cells: Regulation by internal granule pH (1995)
    Springer
    Cell & tissue research 279 (1995), S. 85-92 
    Details
    ISSN: 1432-0878
    Keywords: Exocytosis ; Chromaffin cells ; Catecholamine secretion ; Membrane fusion ; Freeze substitution ; Cow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Adrenal medullary chromaffin cells secrete catecholamines through exocytosis of their intracellular chromaffin granules. Osmotic granule swelling has been implicated to play a role in the generation of membrane stress associated with the fusion of the granule membrane. However, controversy exists as to whether swelling occurs before or after the actual fusion event. Using morphometric methods we have determined the granule diameter distributions in rapidly frozen, freeze-substituted chromaffin cells. Our measurements show that intracellular chromaffin granules increase in size from an average of 234 nm to 274 nm or 277 nm in cells stimulated to secrete with nicotine or high external K+, respectively. Granule swelling occurs before the formation of membrane contact. Ammonium chloride, an agent which inhibits stimulated catecholamine secretion by approximately 50% by altering the intragranular pH, also inhibits granule swelling. In addition, ammonium chloridetreated secreting cells show more granule-plasma membrane contacts than untreated secreting cells. Sodium propionate induces granule swelling in the absence of secretagogue and has been shown to enhance nicotine- and high K+- induced catecholamine release. These results indicate that in adrenal chromaffin cells granule swelling is an essential step in exocytosis before fusion pore formation, and is related to the pH of the granule environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00300694
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    Paper (German National Licenses)
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