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At least 487 records · Page 27Linked to original sources
PubMed1982

Ultrastructure of the nongranulated cells and morphology of the extracellular spaces in the pars distalis of adult and pouch-young tammar wallabies (Macropus eugenii).

Differentiated nongranulated (folliculo-stellate) cells were observed in the centre and periphery of the cords of cells in the pars distalis of the adult tammar wallaby (Macropus eugenii). The nongranulated cells formed follicles containing a small lumen: the cell apices were joined by junctional complexes including zonulae adhaerentes and maculae adhaerentes (desmosomes). Follicles of granulated cells were also occasionally found. Follicles were rarely observed in the adult, but were numerous and generally larger in pouch-young wallabies. Moreover, whereas the involvement of granulated cells in the follicles of the adult was infrequent, they were common components of follicular structures in the pouch-young. The marginal cells at the periphery of the pars distalis in contact with the hypophysial cleft had many of the cytological characteristics of the nongranulated cells in the central pars distalis. In both adult and pouch-young wallabies, nongranulated cells at the periphery of the cell cords were juxtaposed such that they formed "sinusoid-like" spaces or lacunae, presumably as part of the extravascular channel system. The observations are discussed in light of the proposed phagocytotic, metabolite and/or hormone transport and "stem cell" roles attributed to these cells.

Aging↗
PubMed1990

Morphological observations on the extracellular space in the macula densa of the mouse kidney.

Basolateral interstitial spaces (BLIS) of the murine macula densa (MD) are dilated in kidneys fixed either by in vivo glutaraldehyde perfusion or snap freezing-freeze substitution, suggesting that macula densa intercellular spaces may be normally dilated in the functioning nephron. BLIS are also dilated in MD with luminal obstruction with "hyaline" cylinder. This finding might indicate a glomerulo-macular fluid and solute streaming, having an impact on the tubuloglomerular feedback mechanism.

Animals↗
PubMed1987

Schistosoma mansoni: measurement of Na+ ion activity in the tegument and the extracellular spaces using ion-selective microelectrodes.

Ion-selective microelectrodes were used to measure sodium ion activity (aNa) in the tegument and interstitial spaces in adult male Schistosoma mansoni. In RPMI 1640, aNa averaged 31 +/- 13 mM in the tegument, a value significantly less than that in the bathing medium. In the interstitial spaces, it averaged 72 +/- 17 mM, a value nearly the same as that in the bathing medium. In hypo- or hyperosmotic media, aNa in the interstitial spaces varied by a value commensurate with change in aNa in the medium, but aNa in the tegument was changed by only a small amount. Monensin (10 microM), low temperature (20 C), and ouabain (0.3 to 10 microM) all caused significant increases in aNa in the tegument. Hypo- and hyperosmotic media produced initial weight changes followed by gradual recovery back toward original weights. It is concluded that the schistosome is a volume regulating osmoconformer with osmolality of the extracellular fluid approximating that of the bathing medium, but that within the tegument of the parasite, Na+ concentration is controlled by active transport processes.

Animals↗
PubMed1981

Melphalan uptake in relation to vascular and extracellular space of human lung-tumour xenografts.

The effect of melphalan on the growth of 4 different lines of human lung-tumour xenografts has been established. The oat-cell carcinoma was the most sensitive, whereas the adenocarcinoma was the most resistant. Two lines of large-cell anaplastic carcinomas were intermediate in sensitivity. The differences in sensitivity were not reflected in the gross uptake of drug into the tumours. There was, with the exception of the adenocarcinoma line, a marked decrease in uptake per g tumour with increasing tumour size. This was partly caused by a decrease in the vascular supply in the same tumours with increasing tumour size. Extravasation of plasma proteins increased with increasing tumour size in all tumours, but was much less pronounced in the adenocarcinoma than in the other tumour lines. The extracellular volume of the various tumour lines did not vary with tumour size.

Adenocarcinoma↗
PubMed1982

Evans blue dye: its accumulation in extracellular space in relation to endothelial cell basement membrane in normal an atherosclerotic areas of abdominal aorta.

Intravenously (IV) injected Evans blue dye consistently accumulates at particular areas in aortas of normal swine. Theses areas are also where IV injected tracer cholesterol accumulates. We studied the ultrastructural characteristics of blue vs nonblue areas in the abdominal aortas of both control and atherosclerotic swine. In blue areas, the basement membrane was largely missing beneath the endothelial cells in both normal swine and swine with raised atherosclerotic lesions; the basement membrane that was present was often discontinuous. If the basement membrane helps regulate the transport of Evans blue dye across the arterial wall, its absence may play a part in the accumulation of the dye. In raised atherosclerotic lesions, those portions that accumulated Evans blue dye had a larger amount of amorphous extracellular matrix than did nonblue areas. No consistent difference between blue and nonblue areas were seen in the endothelial cell junctions of abdominal aortas in either control or atherosclerotic swine. Similarly, no differences were demonstrable in the number of Golgi complexes, mitochondria, or profiles of smooth or rough endoplasmic reticulum per cell.

Animals↗
PubMed1990

In vivo measurement of intra- and extracellular space of brain tissue by electrical impedance method.

An impedance method was applied to evaluate transcellular fluid shifts in ischaemic brain oedema. The admittances (apparent electrical conductivities) of tissues were measured at varied frequencies based on a simple model of an electrical equivalent circuit for tissues, which consisted of Re (resistivity of extracellular fluid), Ri (resistivity of intracellular fluid) and Cm (capacitance of cell membrane). Calculated were Re, Ri, Rinf (resistivity of total fluid), Re/Ri and alpha (Cole-Cole distribution index) of brain tissue by Cole-Cole an arc of a circle. During ischaemia induced by cat middle cerebral artery occlusion (MCAO), the parameters were examined continuously. After MCAO, cerebral blood flow (CBF) decreased to under 10 ml/100 g/min. Then Re and Re/Ri increased, but Ri decreased. These results indicated that fluid shift from extracellular (EC) to intracellular (IC) space occurred after ischaemic insult. Rinf showed no changes during ischaemia of 30 min, which demonstrated no changes of total fluid volume. Using this impedance technique, fluid accumulation and shift may be examined by changes of Re, Ri, Re/Ri and Rinf in various types of brain oedema in vivo.

Animals↗
PubMed1986

[Dependence of the number of vesicles in vascular smooth muscle cells on the presence of noradrenaline in the extracellular space].

Noradrenaline (NA) effect on the number of vesicles in smooth muscle cells was investigated in small mesenteric arteries of spontaneously hypertensive rats (SHR), aged 8 or 12 weeks, and age-matched normotensive Wistar-Kyoto (WKY) rats. The presence of NA in the incubation medium resulted in an increase in the number of vesicles in SHR of both age groups, but not in WKY. The results are discussed in view of the relationship between the vesicles and Ca transport in smooth muscle cells.

Animals↗
PubMed1993

Penetration of rifampicin into the brain tissue and cerebral extracellular space of rats.

Rifampicin is used to treat neurosurgical shunt infections because of its excellent in-vitro activity against staphylococci and its adequate penetration into the CSF. However, nothing is known about rifampicin concentrations in the cerebral extra-cellular space (CES). We measured the penetration of rifampicin into the CES of anaesthetized rats by microdialysis using low-flow and equilibrium methods. Depending on the method, rifampicin concentrations in the CES were 0.3-1% of the serum concentration or 3-8% of brain tissue concentration, respectively. These experimental data in animals suggest that the recommended dose of rifampicin in man might be inadequate for treatment of some brain infections.

Animals↗
PubMed1976

[The feigned release of cell enzymes. Distribution and transport of cell enzymes within the extracellular space. I (author's transl)].

A sudden increase of enzyme activities in plasma is not necessarily due to a release of enzymes from damaged cells. Three experimental models were used to demonstrate that acute alterations of enzyme activities, as much as +/- 15%, can be caused by fluid-shifts between the intra- and extravascular compartments. Venous occlusion of the forearm by tourniquet produces an increase of the intravascular hydrostatic pressure and subsequently results in a decrease of the plasma volume distal to the tourniquet. Because enzyme molecules are not freely diffusible across the capillary membrane the enzymatic activity increases proportionally to the decrease of plasma volume. Changes in the body posture are accompanied by changes in plasma volume and similarly by alterations in the concentration of plasma-proteins and by alterations in intravascular enzyme activities. Increased enzyme activities in plasma during strenuous physical effort are due chiefly to a concentration of macromolecules within the intravascular space because of a decrease in plasma volume and not to a release of enzymes from hypoxic muscle cells. During recovery after termination of the exercise there is a second and longer lasting increase in enzyme activities in plasma which could be related to a release of enzymes from injured cells. It is suggested that some of these changes could be due to an increase in lymph flow and thereby an increasing transport of enzymes from the interstitial to the intravascular compartment.

Biological Transport↗
PubMed1980

Structural relationships between parenchymal and stromal elements in the pars intermedia of the rat adenohypophysis as demonstrated by extracellular space markers.

The pars intermedia (PI) of the rat adenohypophysis was studied by light and transmission electron microscopy after conventional staining as well as ruthenium red staining, and after systemic injection of horseradish peroxidase. The studies disclose a complex and constant system of two channel types (Type I and Type II channels) formed by PI cells with specific relationships to a very rich nerve supply, to each other, and to a stellate cell type proposed here to represent an element of neuroglia. The channel system could perform a function in the movement of fluids and solutes within the PI which is verturally avascular in the rat as well as in other mammals.

Animals↗
PubMed2005

Kynurenine 3-mono-oxygenase inhibitors reduce glutamate concentration in the extracellular spaces of the basal ganglia but not in those of the cortex or hippocampus.

Kynurenine 3-mono-oxygenase (KMO, kynurenine hydroxylase) inhibitors increase brain kynurenic acid (KYNA) synthesis and cause pharmacological actions possibly mediated by a reduced activity of excitatory synapses. We used in vivo microdialysis and passive avoidance to study the effects of local KYNA or systemic KMO inhibitor administration on glutamate (GLU) neurotransmission. Local application of KYNA (30-100 nM) through reverse microdialysis reduced GLU content in caudate and cortical dialysates by 75 and 55%, respectively. No changes were found in the hippocampus. Systemic administration of Ro 61-8048 (4-40 mg/kg) increased KYNA levels in dialysates obtained from the cortex (from 10.3 +/- 1.9 to 45.5 +/- 15 nM), caudate (from 2.4 +/- 0.8 to 9.5 +/- 0.9 nM) and hippocampus (from 7.7 +/- 1.7 to 19.2 +/- 3.5 nM). It also caused a parallel robust decrease in GLU levels in the dialysates collected from the caudate (from 2.2 +/- 0.5 to 0.63 +/- 0.05 microM) but not in those collected from the parietal cortex or the hippocampus. In a passive avoidance paradigm, the administration of the NMDA receptor antagonist MK-801 (0.1 mg/kg) reduced, while Ro 61-8048 (4-80 mg/kg) did not change the latency time of entering into the dark compartment on the recall trial. Our data show that KMO inhibitors increase brain KYNA synthesis and selectively reduce GLU extracellular concentration in the basal ganglia.

Animals↗
PubMed1984

Photoaffinity labeling of insulin-sensitive hexose transporters in intact rat adipocytes. Direct evidence that latent transporters become exposed to the extracellular space in response to insulin.

Irradiation of intact rat adipocytes with high intensity ultraviolet light in the presence of 0.5 microM [3H] cytochalasin B results in the labeling of Mr 43,000 and 46,000 proteins that reside in the plasma membrane fraction. In contrast to the Mr 46,000 protein, the Mr 43,000 component is not observed in the microsome fraction and exhibits lower affinity for [3H]cytochalasin B. Photolabeling of the Mr 43,000 protein is inhibited by cytochalasin D, indicating it is not a hexose transporter component. The Mr 46,000 protein exhibits characteristics expected for the glucose transporter such that D-glucose or 3-O-methylglucose but not cytochalasin D inhibits its photolabeling with [3H] cytochalasin B. Furthermore, insulin addition to intact cells either prior to or after photoaffinity labeling of the Mr 46,000 protein causes a redistribution of this component from the low density microsomes to the plasma membrane fraction, as expected for the hexose transporter. Photolabeling of transporters in both the low density microsome and plasma membrane fractions is inhibited when intact cells are equilibrated with 50 mM ethylidene glucose prior to irradiation with [3H]cytochalasin B. Incubation of intact cells with 50 mM ethylidene glucose for 1 min at 15 degrees C leads to an intracellular concentration of only 2 mM. Under these conditions, the photoaffinity labeling in intact cells of hexose transporters that fractionate with the low density microsomes is unaffected, indicating these transporters are not exposed to the extracellular medium. In contrast, photolabeling in intact insulin-treated cells of hexose transporters that fractionate with the plasma membrane is inhibited under these incubation conditions. The results demonstrate that insulin action results in the exposure to the extracellular medium of previously sequestered hexose transporters.

3-O-Methylglucose↗
PubMed1978

Evidence for the movement of fluid, macromolecules and ions from the brain extracellular space to the CSF.

This report examines the effect of decreasing serum osmolality on movement into the ventricular system of fluid and of test material injected into the brain. Trace quantities of 22NaCl and 125I-labeled cat serum albumin (CSA) were injected into cerebral white matter of cats. The rates of cerebrospinal fluid volume flow, and appearance of 22Na and 125I-CSA were measured in the effluent fluid using ventriculocisternal perfusion before and while serum osmolality was acutely decreased by the intravenous infusion of a 60 mOsm sucrose solution. As compared to the control period, at the end of the infusion serum osmolality decreased from 321 +/- 4.2 mOsm to 283 +/- 4.0 mOsm and CSF volume flow increased from 21.8 +/- 2.3 microliter/min to 54.9 +/- 4.1 microliter/min (means +/- S.E.). The slope of the regression line describing 22Na influx went from 1.04 to 1.79, while for 125I the slope went from 0 to 1.38. These results suggest that a common pathway may exist for the movement, through the brain and into the ventricular system, of water, ions and large molecules.

Animals↗
PubMed1976

[Cell enzymes in lymph. Distribution and transport of cell enzymes within the extracellular space. II (author's transl)].

Enzyme patterns were measured in the lymph of the thoracic duct of the dog and in the intestinal lymph of the rat. Those patterns were compared to the corresponding activities in blood plasma. From the results it is concluded that under physiological conditions cell enzymes are released into the interstitial space and from there are transported via the lymph into the intravascular space. Only enzymes with a low molecular weight such as myokinase are able to penetrate the capillary membrane, thereby reaching the plasma without being transported exclusively by the lymph. There is a close relationship between the molecular weight of enzymes and their plasma/lymph ratios. In the rat the enzyme patterns in mesenteric lymph nodes and in intestinal mucosa and muscularis (duodenum as well as ileum) were also determined. No direct correlation between those intracellular patterns and the enzyme patterns in the intestinal lymph could be established. The significance of lymph and lymph flow for clinical enzymology is discussed with respect to physiological and pathological conditions. High sensitivity of diagnosis by means of enzyme measurements in plasma can be achieved only if the capillary permeability in the injured organ is high and/or the lymph flow from the organ is not restricted by the injury.

Animals↗
PubMed2000

Fully processed lysyl oxidase catalyst translocates from the extracellular space into nuclei of aortic smooth-muscle cells.

Lysyl oxidase (LO), a secreted protein, was recently identified within the nuclei of vascular smooth-muscle cells (SMC) and 3T3 fibroblasts. A possible pathway by which LO can enter cell nuclei was explored in the present study. SMC were incubated with purified 32-kDa bovine aorta LO that had been fluorescently labeled with rhodamine (TRITC-LO). TRITC-LO entered the cytosol and then rapidly concentrated within the nuclei of preconfluent cultures of these cells, whereas carbonic anhydrase, a protein of similar molecular weight and similarly labeled, did not enter the cells under these conditions. LO that had been reductively methylated at lysine residues with [(14)C]HCHO was also taken up into the cytosolic and nuclear compartments. Intracellular uptake and intracellular distribution were not altered by inhibiting LO activity with beta-aminopropionitrile. An excess of native LO but not of carbonic anhydrase competitively inhibited the uptake of the isotopically labeled enzyme. Thus, once secreted and proteolytically processed, mature LO can enter the cells and concentrate within nuclei in a manner that appears to be specific and independent of its catalytic activity.

3T3 Cells↗
PubMed2005

LEKTI is localized in lamellar granules, separated from KLK5 and KLK7, and is secreted in the extracellular spaces of the superficial stratum granulosum.

Lympho-epithelial Kazal-type-related inhibitor (LEKTI) is a putative serine protease inhibitor encoded by serine protease inhibitor Kazal-type 5 (SPINK5). It is strongly expressed in differentiated keratinocytes in normal skin but expression is markedly reduced or absent in Netherton syndrome (NS), a severe ichthyosis caused by SPINK5 mutations. At present, however, both the precise intracellular localization and biological roles of LEKTI are not known. To understand the functional role of LEKTI, we examined the localization of LEKTI together with kallikrein (KLK)7 and KLK5, possible targets of LEKTI, in the human epidermis, by confocal laser scanning microscopy and immunoelectron microscopy. In normal skin, LEKTI, KLK7, and KLK5 were all found in the lamellar granule (LG) system, but were separately localized. LEKTI was expressed earlier than KLK7 and KLK5. In NS skin, LEKTI was absent and an abnormal split in the superficial stratum granulosum was seen in three of four cases. Collectively, these results suggest that in normal skin the LG system transports and secretes LEKTI earlier than KLK7 and KLK5 preventing premature loss of stratum corneum integrity/cohesion. Our data provide new insights into the biological functions of LG and the pathogenesis of NS.

Adolescent↗
PubMed1999

Resistance of retinal extracellular space to Ca2+ level decrease: implications for the synaptic effects of divalent cations.

Ion-sensitive microelectrodes were used to measure the variations of [Ca2+]o induced by application of low Ca2+ media in the superfused eyecup preparation of the Pseudemys turtle. The aim of the experiments was to evaluate the possibility, suggested by previous studies, that in the deep, sclerad, layers of the retina [Ca2+]o may remain high enough to sustain chemical synaptic transmission even after prolonged application of low-Ca2+ saline. It was found that, at depths of 100-200 micron from the vitreal surface, [Ca2+ ]o did not fall below 1 mM even after application for periods of 30-60 min of nominally Ca2+-free media, and it was >0.3 mM after 30-min application of media containing EGTA and with a Ca2+ concentration of 1 nM. Previous studies in isolated salamander photoreceptors have shown that a reduction of [Ca2+ ]o to 0.3-1.0 mM may result in a paradoxical increase of Ca2+ influx into synaptic terminals due to the reduced screening of negative charge on the external face of the plasma membrane. On the basis of these results, the persistence or enhancement of synaptic transmission from photoreceptors to horizontal cells observed in various retinas treated with low-Ca2+ media may be accounted for within the classical Ca2+-dependent theory of synaptic transmission without invoking a Ca2+-independent mechanism.

Animals↗