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PubMed1977

Sarcotubules and subsarcolemmal caveolae and their continuity with the sarcolemma in frog striated muscle.

After using tannic acid mordanting, T-tubules and subsarcolemmal caveolae show a dense staining with lead citrate, with some increase in contrast also of the sarcolemma, in frog muscle. While a few T-tubules show direct continuity with the extracellular space, the majority open indirectly via caveolae. Caveolae lie immediately beneath the sarcolemma, mainly in a single row, and are more numerous in relation to I-bands.

Animals↗
PubMed1977

Development of cortical spreading depression and of its transition to the caudate nucleus in rats.

The development of Leão's spreading depression (SD) of electroencephalographic activity was studied in young rats by recording the accompanying slow potential changes (SPC). The propagation rate of cortical SD increased from 1.65 mm/min on Day 15 to 2.6 mm/min on Day 20; the increase of SPC amplitude and the decrease of SPC duration were less evident over the same period. The SD elicited in the caudate nucleus by microinjections of KCl did not spread to neocortex in 20- and 30-day-old rats and transition occurred in only 5% of KCl applications in 40-day-old rats. Application of a pyrrolopyrimidine derivative (BW 57-271; 5 mg/kg) increased the cortico-caudate SD transition of 100% in rats aged 20 days or older and increased the SPC amplitude in both structures. The development of SD parameters can be ascribed to dendritic growth and to the decrease of extracellular space; the cortico-caudate propagation block can be ascribed to morphological immaturity of the transitional zone.

Age Factors↗
PubMed1994

The effects of brofaromine, a reversible MAO-A inhibitor, on extracellular serotonin in the raphe nuclei and frontal cortex of freely moving rats.

The effects of brofaromine, a reversible inhibitor of MAO-A, on the extracellular content of serotonin (5-hydroxytryptamine, 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) have been studied in two regions of the rat brain (midbrain raphe nuclei and frontal cortex). In both areas, locally infused brofaromine induced dose-dependent increases of 5-HT which were more marked in the raphe nuclei. Brofaromine increased extracellular 5-HT more markedly than clorgyline, suggesting that other factors (i.e. inhibition of 5-HT uptake) may be involved in its local effects. Systemic (3 mg/kg, s.c.) brofaromine did not modify extracellular 5-HT in any brain area examined. In contrast, the concurrent administration of brofaromine and deprenyl led to significant changes in the concentration of 5-HT and 5-HIAA in the brain extracellular space. The results are discussed in relation to the role of MAO-A in the control of 5-HT output.

Animals↗
PubMed1985

Acetylcholinesterase in human thymus cells.

Acetylcholinesterase (AChE) was long thought to be an enzyme found specifically at the sites of nerve synapses and neuromuscular junctions. It has also been found to occur, however, in cells that are not involved with neurotransmission. This study presents the ultrastructural localization of AChE activity in human thymus cells, using the indirect thiocholine method. Cytochemical demonstration of the enzyme was based on the coupling of acetylthiocholine iodide hydrolysis to the precipitation of heavy metal salts. AChE activity was selectively revealed in the perinuclear cisternae, within the endoplasmic reticulum, and in the Golgi complex of thymic lymphocytes and epithelial cells. Evidence of the presence of reaction product in the latter cells was also found in vesicles that opened into the extracellular space. This is the first demonstration of AChE in human thymus cells. Its possible physiologic role in the thymus gland is discussed.

Acetylcholinesterase↗
PubMed1985

Regeneration of central nervous system axons into an acellular tube in the absence of distal tissue.

To differentiate between local and distant influences on central nerve regeneration, an impervious, stainless-steel cannula, 12 mm long, was placed in the path of severed axons within the corpus callosum of adult rats. The cannula was occluded for 1 week after implantation to prevent herniation of tissue into its lumen. The extracranial end of the tube was plugged with Gelfoam rather than tissue. Inflammatory cells within the tube decreased in number with time and all animals survived for the experiment's duration of 4 to 16 weeks. Some callosal axons grew into the cannula and eventually extended about 1.3 mm. After 8 to 16 weeks, the lumen of the cannula contained many unmyelinated axons, some of which formed fascicles, myelinated axons, demyelinating axons, a few oligodendrocytes, and many astrocytic processes, macrophages, and blood vessels. A striking feature was the linear orientation of cells and their processes. The distal tip of the core resembled a central nervous system explant: it included an appreciable number of growth cones, synaptic terminals embedded in a generous extracellular space, and occasional remyelinating axons. Thus, within an impervious, acellular conduit and in the absence of distal tissue, intrinsic, neuronal processes can be redirected, fasciculate, myelinate, and can regrow alongside glia and endothelium. An indwelling tube, isolating the growth from surrounding brain fluid, may permit assessment of glial, neuronal, and extracellular contributions to the directed regeneration of adult, central axons.

Animals↗
PubMed1993

An ESR study of manganese binding in plant tissue.

Two different fractions of manganese were found in the maize plant root apoplasm (intercellular space containing cell walls) after soaking the roots in MnCl2 solutions (concentration range 0.01-10 mmol.l-1): (a) an Mn2+ fraction in the water free space (WFS) which gave a characteristic six-line spectrum, and (b) an immobilized fraction that gave no detectable ESR spectrum. Both fractions affect proton NMR relaxation (T1) of the tissue water through water exchange across cell membranes. ESR spectra of free and total manganese of the root tissue treated with MnCl2 also revealed different time courses for saturation of WFS and DFS with Mn2+. Binding of manganese in the extracellular space of the tissue seems to be the rate limiting step in permeation of Mn2+ across the root cell membranes.

Electron Spin Resonance Spectroscopy↗
PubMed1966

Electron microscopy: attachment sites between connective tissue cells.

Regions of attachment have been observed between connective tissue cells from four different structures: fibroblasts in embryonic and fetal tendons, fibroblasts in fetal ligamentum nuchae, odontoblasts, and osteoblasts. Morpho logically these sites appear to be focal and to consist of an approximation of the plasma membranes of adjacent cells to within approximately 200 A. In the region of approximation both the extracellular space and the cytoplasm adjacent to the plasmalemma are increased in density. We have postulated a role for these sites in the maintenance of structural integrity.

Animals↗
PubMed1990

[Effect of extracellular calcium on enhancement of norepinephrine release in hippocampus by phorbol ester].

Rabbit hippocampal slices were preloaded with [3H]norepinephrine ([3H]NE) and superfused with medium. Tetrodotoxin(TTX) inhibited [3H]NE release evoked by high K+, but did not affect on that evoked by Ca(2+)-pulse. The facilitatory effect of phorbol ester (PDB) on high K(+)-evoked [3H]NE release was elevated with increasing extracellular Ca2+ concentration. In the case of Ca(2+)-pulse-evoked [3H]NE release, the enhancement by PDB was decreased with increasing Ca2+ concentration in the extracellular space. It was suggested that the facilitation of Ca(2+)-influx was not involved in the mechanism of action of protein kinase C.

Animals↗
PubMed1983

[Study of brain edema by an infusion edema Model--the method and characteristics of the model].

In this report, we have described the way of making the infusion edema model, physiological changes of various parameters during this procedure, distribution of water content in white and gray matter and the light and electron microscopic findings of this edema model, for the further understanding of vasogenic edema of the brain. To make the infusion edema model, 25-G needle was stereotaxically inserted into the left frontal white matter of the cat brain. Through the polyethylene catheter with three way stop cock, this catheter was connected to the pressure transducer and slow infusion pump. By this way, we can monitor the pressure of infusing fluid into the white matter. Normal saline was infused with initial rate of 0.75 microliter/min for the first 2 hours. The inflow rate was increased to 1.5 microliter/min for the next one hour, and then changed to 3.0 microliters/min for maintenance inflow rate. The total amount of infused volume was 0.5 ml in this study. During making the infusion edema model, blood pressure and PaCO2 changed little. Intracranial pressure slightly increased from 5.8 to 15.1 mmHg. Pressure volume index (PVI) changed from 0.74 to 0.64, suggesting the changes of intracranial compliance. The water content measured by specific gravimetric technique showed nearly the same water contents and distribution of edema fluid in the white matter of the cat as in the cryogenic injury model. Pathological findings of this infusion edema model demonstrated that the infused liquid was accumulated in the extracellular space of white matter without damaging the tight junction, and endothelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Distribution of extracellular viral antigen of epidemic hemorrhagic fever in human autopsy cases].

Using improved immunohistochemical methods, repeated PAP and repeated PAP + ABC, we found in the extracellular spaces of autopsy cases of epidemic hemorrhagic fever large amount of viral antigens. Two forms of antigens were found: diffuse soluble antigen and inclusion body like granular antigen. The former was mainly G2 protein and the latter was mainly N protein. They were found in serum, lymph, CSF, edema fluid, fluids in renal, seminal tubules, alveolar and bronchial spaces, peptic, intestinal, pancreatic and thyroidal secretions. In most patients, the diffuse antigens were accompanied by IgG and C1q. A large amount of antigens, were excreted from the patients.

Antigens, Viral↗
PubMedDate not supplied

Hypercapnia and resultant bicarbonate transfer processes in an elasmobranch fish (Scyliorhinus stellaris).

In order to test the effects of hypercapnia on the acid-base status of fish, larger spotted dogfish were exposed to sudden changes of PCO2 in a closed seawater recirculation system. pH, PCO2 and PO2 were determined in arterial blood and seawater. The exchange of bicarbonate between extracellular space (ECS), intracellular space (ICS), and seawater (SW) was obtained from changes of the total bicarbonate amount in ECS and SW. After fourfold increase of PCO2 arterial pH fell markedly, but started to recover immediately towards control values. This was caused by compensatory accumulation of bicarbonate in the ECS. According to the origin of the extracellular bicarbonate increase three periods could be distinguished: 1.-- Bicarbonate transferred from ICS to both ECS and SW; 2. -- Bicarbonate transferred from both SW and ICS to ECS; 3. -- Bicarbonate transferred from SW to both ECS and ICS. After return to normocapnia similar periods occurred with opposite transfer directions and delayed period transitions. In the first period the ICS was found to be the only source for compensatory bicarbonate increases and even in the second period the ICS contributed to compensation of the extracellular pH. Thus bicarbonate exchange with the ICS appears to be an important regulatory mechanism diminishing the extracellular pH variations after changes in PCO2, before other compensatory mechanisms are initiated.

Animals↗
PubMed1994

In vivo differentiation of edematous changes after stroke in spontaneously hypertensive rats using diffusion weighted MRI.

Apparent diffusion coefficients (ADCs) of tissue water were determined in chronic brain lesions of a rat stroke model, the stroke-prone spontaneously hypertensive rat, and compared with histology. ADCs increased in the order normal < edema < gliosis < cyst. The differences between individual groups were statistically significant. The increase in ADC is thought to mainly reflect a relative increase in the extracellular space in brain tissue. ADC may be a new parameter for tissue characterization.

Animals↗
PubMed1993

Hindered diffusion of high molecular weight compounds in brain extracellular microenvironment measured with integrative optical imaging.

This paper describes the theory of an integrative optical imaging system and its application to the analysis of the diffusion of 3-, 10-, 40-, and 70-kDa fluorescent dextran molecules in agarose gel and brain extracellular microenvironment. The method uses a precisely defined source of fluorescent molecules pressure ejected from a micropipette, and a detailed theory of the intensity contributions from out-of-focus molecules in a three-dimensional medium to a two-dimensional image. Dextrans tagged with either tetramethylrhodamine or Texas Red were ejected into 0.3% agarose gel or rat cortical slices maintained in a perfused chamber at 34 degrees C and imaged using a compound epifluorescent microscope with a 10 x water-immersion objective. About 20 images were taken at 2-10-s intervals, recorded with a cooled CCD camera, then transferred to a 486 PC for quantitative analysis. The diffusion coefficient in agarose gel, D, and the apparent diffusion coefficient, D*, in brain tissue were determined by fitting an integral expression relating the measured two-dimensional image intensity to the theoretical three-dimensional dextran concentration. The measurements in dilute agarose gel provided a reference value of D and validated the method. Values of the tortuosity, lambda = (D/D*)1/2, for the 3- and 10-kDa dextrans were 1.70 and 1.63, respectively, which were consistent with previous values derived from tetramethylammonium measurements in cortex. Tortuosities for the 40- and 70-kDa dextrans had significantly larger values of 2.16 and 2.25, respectively. This suggests that the extracellular space may have local constrictions that hinder the diffusion of molecules above a critical size that lies in the range of many neurotrophic compounds.

Animals↗
PubMed1981

Plasma and interstitial fluid volume in extensive skin disease.

Plasma volume and extracellular fluid volume were determined simultaneously in 17 patients with extensive skin disease and 18 matched normal subjects after an intravenous bolus injection of 131I-labeled human serum albumin and inulin. The patients had a decrease in plasma volume (-6%), which, however, was statistically significant only when related tao body weight or surface area. There was a concomitant increase in extracellular fluid volume (+7%) and interstitial fluid volume (+12%). These deviations from control data were statistically significant neither in absolute values nor when related to body size. Interstitial fluid volume was calculated as the difference between extracellular fluid volume and plasma volume. The mean plasma volume: interstitial fluid volume ratio was significantly lower in the patients (0.35 +/- 0.05 SD) than in the control group (0.42 +/0 0.05 SD) (p < 0.001). These results show that a shift of fluid from the intra- to the extracellular spaces is present in patients with extensive skin disease. Elevated microvascular water filtration in the skin is suggested as a major mechanism of this abnormal fluid distribution.

Body Water↗
PubMed1999

Mechanism of endothelin-1-(1-31)-induced calcium signaling in human coronary artery smooth muscle cells.

We have found that human chymase produces a 31-amino acid endothelin [ET-1-(1-31)] from the 38-amino acid precursor (Big ET-1). We examined the mechanism of synthetic ET-1-(1-31)-induced intracellular Ca2+ signaling in cultured human coronary artery smooth muscle cells. ET-1-(1-31) increased the intracellular free Ca2+ concentration ([Ca2+]i) in a concentration-dependent manner (10(-14)-10(-10) M). This ET-1-(1-31)-induced [Ca2+]i increase was not affected by phosphoramidon, Bowman-Birk inhibitor, and thiorphan. The ET-1-(1-31)-induced [Ca2+]i increase was not influenced by removal of extracellular Ca2+ but was inhibited by thapsigargin. ET-1-(1-31) at 10(-12) M did not cause Ca2+ influx, whereas 10(-7) M ET-1-(1-31) evoked marked Ca2+ influx, which was inhibited by nifedipine. ET-1-(1-31) also increased inositol trisphosphate formation. These results suggest that the ET-1-(1-31)-induced [Ca2+]i increase at relatively low concentrations is attributable to the release of Ca2+ from inositol trisphosphate-sensitive intracellular stores, whereas Ca2+ influx into the cells evoked by high concentration of ET-1-(1-31) probably occurs through voltage-dependent Ca2+ channels. We concluded that the physiological activity of ET-1-(1-31) may be attributable to Ca2+ mobilization from intracellular stores rather than influx of Ca2+ from extracellular space.

Arteries↗
PubMed1993

Amino acids in cerebrospinal and brain interstitial fluid in experimental pneumococcal meningitis.

Excitatory amino acids are increasingly implicated in the pathogenesis of neuronal injury induced by a variety of CNS insults, such as ischemia, trauma, hypoglycemia, and epilepsy. Little is known about the role of amino acids in causing CNS injury in bacterial meningitis. Several amino acids were measured in cerebrospinal fluid and in microdialysis samples from the interstitial fluid of the frontal cortex in a rabbit model of pneumococcal meningitis. Cerebrospinal fluid concentrations of glutamate, aspartate, glycine, taurine, and alanine increased significantly in infected animals. Among the amino acids with known excitatory or inhibitory function, interstitial fluid concentrations of glutamate were significantly elevated (by 470%). Alanine, a marker for anaerobic glycolysis, also increased in the cortex of infected rabbits. The elevated glutamate concentrations in the brain extracellular space suggest that excitotoxic neuronal injury may play a role in bacterial meningitis.

Amino Acids↗
PubMed1999

[Dependence of myocardial damage on the anion composition and osmotic pressure in the extracellular fluid during "calcium paradox" in rats].

The data obtained reveal that elevation of extracellular osmolarity with sucrose during reintroduction of Ca-containing medium after 10 minutes of Ca2+ removal prevents loss of haemoglobin in a concentration-dependent mode. Reducing the extracellular osmolarity of the reperfusion medium by means of decreasing the concentration of sodium chloride and calcium chloride exacerbates the loss of haemoglobin from the cardiomyocytes. There is a close correlation between the water contents in tissues and the loss of haemoglobin during the "calcium paradox". The findings suggest dependence of the heart damage during the "calcium paradox" on anionic composition of extracellular space and activity of anionic transporters.

Animals↗
PubMed1975

Potassium. The intracellular cation.

Normally the concentration of potassium in the extracellular space is maintained within relatively narrow bounds; in disease, these boundaries may be exceeded. Hyperkalemia and sometimes hypokalemia must be considered medical emergencies, to be treated promptly, effectively, and appropriately.

Bicarbonates↗