Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “EXTRACELLULAR SPACE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources
PubMed1985

Early atherogenesis in White Carneau pigeons. II. Ultrastructural and cytochemical observations.

The addition of cholesterol (0.5%) to the diet of White Carneau pigeons induces site specific, temporally predictable, atherosclerotic lesions. The earliest lesions, which occurred after 3 weeks, were small (less than 2500 sq mu in surface area) and were composed primarily of macrophage foam cells (94% of lesion volume). With a prolonged time on the diet the lesions expanded due to increases in the number and size of foam cells, increases in the amount of extracellular space, and influx of smooth muscle cells. Macrophage foam cells in advanced lesions composed 61% of the lesion volume, smooth muscle cells 25%, and extracellular space 14%. Concurrent with the alteration in the constituency of the lesion, redistribution of lipid within foam cells was noted. Lipid in small lesions was primarily cytoplasmic (88%), with the remaining 12% in acid-phosphatase-positive secondary lysosomes. In more advanced lesions, 34% of the lipid was cytoplastic and 66% was lysosomal. The changes in large lesions appeared to be a function of lesion age, because at the growing edge of large lesions both composition and lipid distribution resembled those of small early lesions.

Acid Phosphatase↗
PubMed1985

Shiverer and normal peripheral myelin compared: basic protein localization, membrane interactions, and lipid composition.

We have correlated membrane structure and interactions in shiverer sciatic nerve myelin with its biochemical composition. Analysis of x-ray diffraction data from shiverer myelin swollen in water substantiates our previous localization of an electron density deficit in the cytoplasmic half of the membrane. The density loss correlates with the absence of the major myelin basic proteins and indicates that in normal myelin, the basic protein is localized to the cytoplasmic apposition. As in normal peripheral myelin, hypotonic swelling in the shiverer membrane arrays occurs in the extracellular space between membranes; the cytoplasmic surfaces remain closely apposed notwithstanding the absence of basic protein from this region. Surprisingly, we found that the interaction at the extracellular apposition of shiverer membranes is altered. The extracellular space swells to a greater extent than normal when nerves are incubated in distilled water, treated at a reduced ionic strength of 0.06 in the range of pH 4-9, or treated at constant pH (4 or 7) in the range of ionic strengths 0.02-0.20. To examine the biochemical basis of this difference in swelling, we compared the lipid composition of shiverer and normal myelin. We find that sulfatides, hydroxycerebroside, and phosphatidylcholine are 20-30% higher than normal; nonhydroxycerebroside and sphingomyelin are 15-20% lower than normal; and ethanolamine phosphatides, phosphatidylserine, and cholesterol show little or no change. A higher concentration of negatively charged sulfatides at the extracellular surface likely contributes to an increased electrostatic repulsion and greater swelling in shiverer. The cytoplasmic surfaces of the apposed membranes of normal and shiverer myelins did not swell apart appreciably in the pH and ionic strength ranges expected to produce electrostatic repulsion. This stability, then, clearly does not depend on basic protein. We propose that P0 glycoprotein molecules form the stable link between apposed cytoplasmic membrane surfaces in peripheral myelin.

Animals↗
PubMed1996

Control of Ca2+ homeostasis in neuronal cells.

The intracellular free Ca2+ concentrations show complex fluctuations in time and space in response to a variety of stimuli, and act as a pluripotent signal for many neuronal functions. Activation of cells is associated with Ca2+ influx from the extracellular space through voltage-dependent and/or receptor-operated Ca2+ channels localized on the plasma membrane, and/or by release of Ca2+ from intracellular stores to reach Ca2+ concentrations of up to micromolar levels. During cell relaxation, calcium concentration decreases to resting levels via ATP-driven Ca2+ transport both to the extracellular space and into the intracellular stores. Thus, Ca2+ homeostasis in neuronal cells is maintained by several systems differing by their mechanisms, biochemical characteristics and intracellular localization. Their biochemical properties and physiological importance as well as cellular localization are discussed in this short review.

Animals↗
PubMed1982

Do neuronal signals regulate potassium flow in glial cells? Evidence from an invertebrate central nervous system.

Experiments were conducted with the aid of intracellular microelectrodes to study physiological properties of neuropile glial cells in the central nervous system of the medicinal leech. The results showed significant contributions of both K+ and Cl- ions to the membrane potential. The transmitter substance 5-hydroxytryptamine increased the K+ conductance of the cell membrane. On the basis of these experiments, a model for potassium homeostasis in leech neuropile is suggested, according to which excess K+ ions in the extracellular space lead to passive KCl fluxes across the glial cell membrane and the transmitter 5-hydroxytryptamine induces a K+ release from glial cells into the extracellular space. Since 5-hydroxytryptamine is known to be an inhibitory transmitter in the leech central nervous system, this release will occur in regions with inactive neurons, which may be specially well suited for neuronal reaccumulation of K+ ions.

Animals↗
PubMed1995

Pathology of the transmissible spongiform encephalopathies with special emphasis on ultrastructure.

The transmissible spongiform encephalopathies are a group of genetic and infectious disorders which are exemplified by scrapie in animals and Creutzfeldt-Jakob disease in humans. The spongiform encephalopathies are characterized by symmetrical vacuolation of neurons and neuropil. Amyloid plaque formation similar to that found in Alzheimer's disease is conspicuous in many, but not all, of these diseases. The sub-cellular pathology features of the spongiform encephalopathies have been studied by conventional transmission electron microscopy, scanning electron microscopy, freeze fracture, negative staining and most recently by application of immunogold labelling methods. Although these studies have revealed many unusual structures, convincing virus-like particles have not been demonstrated. Considerable data, including important transgenic mouse studies, now suggest that a single cellular protein, designated prion protein, is necessary for infection. Ultrastructural immunogold studies have shown that prion protein is released from the surface of neurons and neurites, diffuses through the extracellular space around infected cells where it accumulates and finally becomes aggregated as amyloid fibrils. It is likely that the accumulation of prion protein within the extracellular space is instrumental in causing nerve cell dysfunction and, ultimately, neurological disease.

Amyloid↗
PubMed1999

[Degranulation of human eosinophils in nasal allergy].

The localization of eosinophil peroxidase (EPO), one of the basic proteins in eosinophil grunules, was studied in the nasal mucosae of nasal allergy patients. EPO in granules was initially induced into the cytoplasm via finetubules and then diffused into the extracellular space through micro-destruction of the plasma membrane. When the eosinophil lysis was advanced a large amount of granule countents was released into the extracellular space. The total number of eosinophils which migrated to epithelial region was not significantly different between in the damaged epithelium and in the intact one. But the rate of cytolytic eosinophils was significantly higher in the area of severely shedded epithelium than in the area of intact epithelium. In conclusion, the degranulation of eosinopils in nasal allergy was induced by lysis rather than by exocytosis and many cytolytic eosinophils caused epithelial shedding.

Adult↗
PubMed1986

Effect of acute alcoholic intoxication on myocardial electrolyte and water distributions.

Myocardial electrolyte distributions and sarcolemmal permeability in vivo were compared among control, acutely alcoholic, and recovery groups of rats. Rats in the alcoholic group received an intraperitoneal dose of 56 ml 12.5% ethanol per kg rat over a 5-h period. One hour after receiving the last injection of ethanol, blood was withdrawn from the right atrium and the heart excised. Rats in the recovery group had one day to recover from the alcohol treatment. Control rats were injected with n-saline instead of ethanol. Myocardial extracellular space was assessed by morphometric and tracer techniques. Results indicate that myocardial water content increases during acute alcoholic intoxication and this increase is restricted to the extracellular space. The nominal cellular concentration of potassium increased nearly 10% while that of sodium fell by nearly one-third. Plasma concentration of magnesium increased markedly (36%) and that of calcium fell slightly (5%). The results suggest that the myocardial sarcolemma is not rendered leaky by acute ethanol intoxication even several days after binge drinking, when the skeletal muscle cell sarcolemma appears to become slightly more permeable.

Alcoholic Intoxication↗
PubMed1977

The appearance of the outflow apparatus of the eye after staining with ruthenium red.

The outflow apparatus from adult baboon and rabbit eyes was stained with the inorganic dye ruthenium red. The ruthenium reaction product coated the surface of the trabecular meshwork cells and the canalicular endothelial cells. Deposits also impregnated the various connective tissue elements within the trabeculae and the extracellular spaces of the endothelial meshwork. A fine fibrillar network could also be identified with ruthenium red and this was present in the trabecular cores and the extracellular spaces of the endothelial meshwork. It was considered that the fibrillar network may represent a matrix of glycosaminoglycans and glycoproteins. The significance of these materials in relation to aqueous outflow was discussed.

Animals↗
PubMed1984

Model of electroretinogram b-wave generation: a test of the K+ hypothesis.

Generation of the electroretinogram b-wave is simulated with a computer model representing a dark-adapted amphibian retina. The simulation tests the K+ hypothesis of b-wave generation, which holds that b-wave currents arise from localized Müller cell depolarizations generated by light-evoked increases in extracellular K+ concentration, [K+]o. The model incorporates the following components and processes quantitatively: 1) two time-dependent K+ sources representing the light-evoked [K+]o increases in the inner and outer plexiform layers, 2) a time- and [K+]o-dependent K+ sink representing the [K+]o decrease in the rod inner segment layer, 3) diffusion of released K+ through extracellular space, 4) active K+ reuptake and passive K+ drift across the Müller cell membrane, 5) spatial variations in the tortuosity factor and the volume fraction of extracellular space, 6) an extraretinal shunt resistance. Müller cells are modeled with 1) cytoplasmic resistance, 2) spatial variations in membrane permeability to K+, and 3) a membrane potential specified by the Nernst equation and transmembrane current flow. For specified K+ source and sink densities, the model computes [K+]o variations in time and retinal depth. Based on these [K+]o distributions, Müller cell potentials, current source-density profiles, and intraretinal and transretinal voltages are calculated. Imposed [K+]o distributions similar to those seen experimentally during the b-wave lead to the generation of a transient b-wave response and to a prolonged Müller response in the model system. These response time courses arise because the b-wave is dominated by the short-lived distal [K+]o increase, while the Müller response primarily reflects the long-lived proximal [K+]o increase. Current source-density distributions and intraretinal voltage profiles that are generated by the model at the peak of the b-wave closely resemble experimental results. The model generates a realistic slow PIII potential in response to prolonged [K+]o decreases in the distal retina and reproduces the K+ ejection results of Yanagida and Tomita (50) accurately. Simulations also suggest that tissue damage caused by K+-selective micropipettes in experimental preparations can lead to an underestimation of the distal [K+]o increase. The simulations demonstrate that the spatiotemporal properties of intraretinal b-wave voltages and currents and Müller cell responses can be generated according to the K+ hypothesis: by passive Müller cell depolarization driven by variations in [K+]o.

Animals↗
PubMed1989

[Use of calciotropic agents in psychiatry and neurology].

Neurotransmission of impulses is a phenomenon activated by the calcium signal. Therefore changes of calcium homeostasis in the nerve cell always influence more or less this function. Changes of calcium homeostasis in the nerve cell occur under various pathological conditions, incl. hypoxia. The cytosol of the neuron is excessively saturated with calcium ions due to a shift from the extracellular space. The affected neurons release humoral factors, so-called neurotransmitters, which by receptor-controlled activation of calcium channels enhance the calcium influx from the extracellular space. After exhaustion of defense mechanisms by which the nerve cell gets rid of excessive calcium its metabolism is affected and necrosis may occur. This toxic effect of calcium can be prevented by administration of calcium antagonists represented by 1. blockers of slow calcium currents and 2. calmodulin inhibitors. The author gives an account of antipsychotic, analgetic, myorelaxing and vasodilatating effects of some calcium antagonists, and their clinical application is discussed. The author emphasizes also some possible undesirable effects of some neuroleptics mediated by the calciotropic mechanism, in particular during long-term administration. They are manifested by increased urinary calcium losses and impaired bone mineralization. Delayed regression of myorelaxation during anaesthesia is also important and must be taken into account in patients treated for prolonged periods with blockers of calcium currents.

Calcium Channel Blockers↗
PubMed1971

Regression of early cholesterol-induced aortic lesions in rhesus monkeys.

The reversibility of early uncomplicated cholesterol-induced aortic lesions in rhesus monkeys was investigated. Three groups of Rhesus monkeys were used: the control group was fed a chow diet for 8 weeks; the progression group was fed an atherogenic diet for 8 weeks and the regression group was fed an atherogenic diet for 8 weeks and returned to the chow diet for 16 weeks. The lesions produced in the progression animals characteristically contained many lipid-laden monocytes immediately beneath the endothelium, abundant lipid droplets in intimal smooth muscle cells and moderate amounts of lipid in the extracellular spaces. Lesions in regression animals contained few lipid-laden monocytes, less lipid in smooth muscle cells and larger and more numerous lipid particles in the extracellular spaces. The results indicate that aortic lesions can be produced predictably after 8 weeks of feeding a high-cholesterol diet and that qualitative changes in the lesions occur 16 weeks after withdrawal from the diet.

Animals↗
PubMed1997

The early neuronal organization predicts the path followed by some major axonal bundles in the embryonic brainstem.

In the embryonic CNS, preformed pathways precede the growth of axonal fasciculi [Katz M. J. and Lasek R. J. (1980) Cell Motil. 1, 141-157; Katz M. J. et al. (1980) Neuroscience 5, 821-833]. What are the developmental events that lead to the elaboration of these preformed pathways? To answer this question, we investigated the organization of the primitive neural tube and more particularly the arrangement of the early-generated cells using [3H]thymidine autoradiography or bromodeoxyuridine. Our data suggest that the position of early-generated cells might be involved in the setting of such pathways. In the brain stem of E12(0) (12 days and 0 h) and E12(15) rat embryos, the first-generated cells were organized into three longitudinal columns associated with glycoconjugate-rich extracellular spaces in the adjacent primitive marginal layer. Also, axons traced with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) were contiguous to the early-generated cellular columns and represented the primordium of the medial longitudinal fasciculus, the lateral longitudinal tract and the mesencephalic trigeminal tract. Our results show a correlation between the organization of early-generated cells, likely neurons, and the pattern of extracellular spaces in the marginal layer where axons grow. It has been reported in the literature that neurons produce elements of the extracellular matrix such as growth-modulating molecules or space-creating molecules. We therefore suggest that the position of early-generated neurons could be involved in the elaboration of a template for the setting of some major longitudinal tracts during embryonic development of the brainstem.

Animals↗
PubMedDate not supplied

Glucose concentration at possible sensor tissue implant sites.

It is generally acknowledged that the ideal automatic insulin infusion system would be a closed loop that metered insulin delivery in response to a feedback sensor such as an implantable glucose detector. Most current efforts are aimed at a transducer located within the blood vascular tree. We believe that the blood constitutes an especially hostile environment for such a device. The possibility of placing the sensor with a reasonably rapid response to dynamic alterations in glucose metabolism in a space containing fluid outside the bloodstream was studied. The subcutaneous extracellular space, peritoneum, pleura, and pericardium were included. Generally, the concentration of glucose ranged between 50 and 115 mg/dl under steady-state conditions. The experimental design did not permit monitoring rapid responses to artificially induced dynamic changes. There were several situations where lower values were recorded, suggesting that a wide range of concentrations might occur. The authors have concluded that these experimental results are compatible with the possibility of a suitable locus for the glucose sensor in the extracellular, extravascular space.

Animals↗
PubMed1982

Interstitial space of mouse skeletal muscle.

1. A new preparation of mouse skeletal muscle, prepared from pectoral muscles, is described.2. The sorbitol space of this muscle, both in vivo and in vitro, has been measured with dynamic loading of the muscle in vitro as an experimental variable.3. The Na(+) and K(+) contents of the muscle have been determined and the apparent intracellular concentration for these ions calculated both in vivo and after incubation in vitro.4. Histological studies on the incubated muscle have been made so as to permit comparison of the changes in the chemical measurements with changes in the ultrastructure of the muscle.5. The results of these experiments show that there is an increase in the apparent extracellular space of the muscle following incubation. This increase is constant, and independent of the load, with the important exception that unloaded muscles do not reach an equilibrium during the period of incubation and have a much greater apparent extracellular space.6. Intracellular Na(+) and K(+) concentrations are consistent with the sorbitol being restricted to an extracellular phase in the loaded muscle; but the evidence implies that sorbitol in the unloaded muscle penetrates into a space from which Na(+) is excluded.7. The total water content of the muscle per unit weight is unchanged by incubation, indicating that the apparent change in sorbitol space is in the ratio of intracellular space to extracellular space rather than by addition of water to the extracellular space. The significance of these results is discussed with reference to the use of such preparations for in vitro studies.

Animals↗
PubMed1983

Actin in cellular components of the basement membrane of the compound eye of a blowfly.

The so-called 'basement membrane' of arthropod compound eyes is known to be of heterogeneous origin (Odselius and Eloffson 1981). A major contribution in Diptera with open rhabdoms is provided by a pigmented component which lies at the basal end of the extracellular space of each ommatidium and fills it, the glial plug. Ancillary components consist of the expanded tips of cone cell processes. Each glial plug exhibits two distinct regions: ramifying processes extend into the extracellular space and contain numerous pigment granules, while proximally the cytoplasm is devoid of granules but packed with bundles of cross-linked microfilaments that bind the fluorescent F-actin probe NBD-phallacidin strongly and antibodies to scallop actin weakly. Cone cell expansions also contain microfilaments and exhibit the same binding properties. The proximal faces of the cells of the glial plugs and of the cone cell expansions are covered with a coarsely fibrillar extracellular matrix. Some actin bundles appear to be attached to the plasma membranes at their ends, although the reality of this arrangement is still in question. Cellular components of the basement membrane are bonded together by their extracellular matrices, so that collectively they provide a reinforced network that retains the retina. Bundles of axons from the photoreceptors and tracheae that supply the retina with tracheoles pass through the spaces in this network.

Actins↗
PubMed1993

Pathway of insulin in pancreatic tissue on its release by the B-cell.

Insulin was revealed in the extracellular space and blood capillaries of the rat pancreas by applying protein A-gold immunocytochemistry. On the discharge by the B-cell, insulin diffuses in the extracellular space and interacts with the plasma membrane of all pancreatic cells. For the B-cell, the interstitial microvillar plasma membrane domain was preferentially labeled compared with the flat domain. In contrast, the digitations and flat domains of the basal plasma membrane of the acinar cells were equally labeled. In the endothelium, the labeling was superior in fenestrated areas than in the high cytoplasmic ones, the fenestrae, the luminal and abluminal plasma membranes being labeled. In the cytoplasmic areas the plasmalemmal vesicles were significantly labeled; the intercellular junctions were not. These results indicate that upon binding to the membrane, the transfer of insulin across the capillaries occurs through both the fenestrations and the vesicular system. The labeling of insulin in the subendothelial space and blood capillaries decreased significantly from the insular to the peri-insular and further to the teleinsular regions, demonstrating that insulin levels, high in insular tissue, decrease very rapidly as insulin circulates through and out of the pancreas. The pancreatic cells are thus exposed to very high levels of insulin that vary according to the regions, probably contributing to the topographical partition of the acinar parenchyma into peri-insular and teleinsular tissues.

Animals↗
PubMed1990

Effects of treatment with noradrenaline and isoproterenol on the excretory portion of the submaxillary gland in the rat: an ultrastructural study.

The aim of this study is to evaluate the modification of the excretory portion and its comparison with the acinus, on stimulating the rat submaxillary gland with noradrenaline and isoproterenol. Stimulation of the submaxillary gland with these drugs for a period of 10 min produces different effects in the acinus and excretory portion. The secretory granules do not show reorganisation of their contents after stimulation with isoproterenol, while in the acinus the material is reorganised forming concentric laminae. After stimulation with noradrenaline, the acinar lumen increases its diameter with respect to the control groups, while this same stimulus does not modify the diameter of the ductal lumen. After stimulation with noradrenaline, the extracellular spaces are consistently obliterated in all ducts except the striated duct, in which the behaviour is variable as in the acinus. In these two latter cases, the extracellular spaces are visible in some cases and not in others. Stimulation with noradrenaline is a potent stimulus of synthesis in both the granular undulated duct and the striated undulated duct, while in the acinus this effect is produced by isoproterenol.

Animals↗