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At least 19 recordsLinked to original sources
PubMed1978

[Distribution of water between the extracellular and intracellular space in rats].

In anesthetized rats the renal pedicules were clamped and the solution with THO, antipyrine, thyocyanate, inulin, 22Na, 36Cl, 82Br was injected into the tail artery. The space of distribution of THO was 65.1% body weight, antipyrine--81.9%. The volumes of distribution of 22Na (27.4%) and thyocyanate (26.9%) were higher than the 36Cl (24.8%) and 82Br (25.6%) spaces. Inulin space was 13.8%. There was no difference between the volume of distribution of the substances in female and male rats. The same spaces of the substances (except inulin) were determined in rats with intact kidneys. After i.a. administration of 5 ml/100 g body weight of Ringer's solution the recovery of all the substances was about 100%. The data obtained indicate that antipyrine cannot be used for estimation of the total body water in rats. For the measurement of extracellular fluid it is better to use radioisotopes 82Br, 36Cl or 22Na; more variable data were observed with thyocyanate and inulin.

Animals↗
PubMed1976

The kinetics of efflux of 5,5-dimethyl-2,4-oxazolidinedione (DMO) from the myocardium.

1. The efflux of 14C-labelled 5,5-dimethyl-2,4-oxazolidinedione (DMO) from the myocardium of the rabbit has been studied. The perfusate pH was 7-38. 2. The effluent curve is complex and appears to be the resultant of movement between at least four compartments. 3. The first two probably represent intravascular and extracellular compartments; the last two have smaller rate constants and may represent intracellular spaces. Intracellular pH (pHi) calculated from the effluent curve was 7-23 +/- 0-05. pHi estimated from the steady-state distribution volume of DMO was 7-28 +/- 0-02. The existence of two intracellular compartments suggests that DMO is not homogeneously distrubted in the myocardium. It is suggested that the apparent greater buffering capacity of cardiac than skeletal muscle can be explained by the greater number and volume of mitochondria in the myocardium, compartmentalization of DMO and assumptions inherent in the DMO method for the measurement of pHi.

Animals↗
PubMed1978

Some hemodynamic and hydroelectrolytic alterations of chronic salt deprivation.

Male Wistar rats were fed for 1 month on a low salt diet and compared with control animals. The body fluids are decreased, and this diminution takes place due to the decrease of the total water, extracellular space, intracellular space, plasma volume and interstitial liquid. In the muscle, the alterations in the water composition were similar to the modifications observed in the whole animal. The electrolytic composition of the muscle showed a decrease in the sodium content; no modifications were found in the chloride content and there was a slight decrease in the potassium content. The cardiac rate was increased and the arterial pressure and heart weight also showed a slight augmentation. The infusion of antibodies against angiotensin II provoked a similar decrease in arterial pressure in both groups of animals. These results show an alteration of the hydroelectrolytic metabolism in salt-deprived rats and that the circulatory function is adapted to this new situation.

Angiotensin II↗
PubMed1979

Potassium, sodium, and the intracellular fluid space of cells from bone.

Cells enzymatically dispersed from fetal rat calvaria were analyzed for sodium and potassium content and intracellular fluid space (ICF). Even when obtained in comparatively high yield, the cells are damaged by the isolation procedure as evidenced by high sodium and low potassium content immediately after isolation. During a post-incubation period potassium is accumulated and sodium extruded to steady-state levels. Although electrolyte content of cells after recovery did not vary as a function of cell yield, ICF was increased in cells obtained in lower yield, suggesting cell swelling as a result of membrane damage. The weighted mean values obtained for the best cell preparations were 117 mM K+ and 27 mM Na+. Based on DNA assay of isolated cells and the whole tissue, 20- to 21-day calvaria were found to have an average of 8.1 x 10(6) cells/calvarium. Combining cell data with analysis of total tissue sodium, potassium, and water, it was concluded that the tissue extracellular sodium is in equilibrium with blood but that the potassium concentraiton is approximately 5-fold higher than blood levels.

Animals↗
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↗
PubMed1976

Dexamethasone treatment during hemorrhagic shock: changes in extracellular fluid volume and cell membrane transport.

Changes in extracellular fluid volume and cell membrane transport during hemorrhagic shock and the effects of dexamethasone treatment on these changes were measured. It is well known that prolonged hemorrhagic shock leads to irreversible changes and a progressive decrease in blood pressure despite reinfusion for lost blood. Pharmacologic doses of glucocorticoids provide some protection against these changes. Therefore, one purpose in the present study was to identify possible sites of glucocorticoid action whicy may prevent the irreversible changes from occurring. The extracellular fluid volume in normal control, nontreated dogs in shock, and dexamethasone-treated dogs in shock were measured by a dilution technique, using [35S] sodium sulfate. Cell membrane cation transport capabilities were measured in liver slices, diaphragm slices, and red blood cells taken from normal control, nontreated rats in shock, and dexamethasone-treated rats in shock. The accumulation of radioactivity by the tissues incubated with 22Na served as an indicator of cell membrane ion transport capabilities. The results indicate that in animals subjected to prolonged hemorrhagic shock, there is a fluid shift from the extracellular space into intracellular spaces, reducing blood volume. Cell membranes are damaged and transport mechanisms are altered; therefore, the cells are unable to extrude ions along with water. Dexamethasone treatment was shown to prevent extracellular fluid volumes from decreasing below that amount due to the plasma lost during hemorrhage. Also, it prevented some cell membrane damage and maintained membrane transport mechanisms near normal. In addition, at the onset of dexamethasone injection, blood pressure increased, and urine output was restored.

Animals↗
PubMed1979

Distribution of tryptophan and tyrosine in unipolar affective disorders as defined by multicompartmental analysis.

As requirements for tryptophan for synthesis of protein and 5-hydroxytryptamine were comparable in rat brain, during depletion of tryptophan there could be competition between the two pathways for the amino acid. This implied that tryptophan should be rate-limiting for protein synthesis and this was found in the short term when concentrations of the amino acid were reduced in rats. Multicompartmental studies of tryptophan and tyrosine in controls and patients subject to unipolar depression defined two main pools of the amino acid provisionally assigned to extracellular and intracellular spaces. For tyrosine, mean values for the extracellular space were comparable to those of controls. The concentration of tyrosine was low in the intracellular space in both depressed and recovered patients, but the raised fractional clearance rates for this compartment during depression had returned to normal on remission. Plasma tryptophan concentrations were significantly reduced in depression with intermediate values after recovery. This suggested that the procedure used may have been mildly stressful and that this had evoked an idiosyncratic response to the stress in the depressed patients, which was characterized by inability to maintain concentrations of this amino acid in plasma. The findings for both amino acids may have a bearing on the aetiology of unipolar affective disorder.

Adult↗
PubMed1979

Electrical properties of spherical syncytia.

Syncytial tissues consist of many cells whose intracellular spaces are electrically coupled one to another. Such tissues typically include narrow, tortuous extracellular space and often have specialized membranes at their outer surface. We derive differential equations to describe the potentials induced when a sinusoidal or steady current is applied to the intracellular space with a microelectrode. We derive solutions for spherical preparations with isotropic properties or with a particular anisotropy in effective extracellular and intracellular resistivities. Solutions are presented in an approximate form with a simple physical interpretation. The leading term in the intracellular potential describes an "isopotential" cell in which there is no spatial variation of intracellular potential. The leading term in the extracellular potential, and thus the potential across the inner membranes, varies with radial position, even at zero frequency. The next term of the potentials describes the direct effects of the point source of current and, for the parameters given here, acts as a series resistance producing a large local potential drop essentially independent of frequency. A lumped equivalent circuit describes the "low frequency" behavior of the syncytium, and a distributed circuit gives a reasonably accurate general description. Graphs of the spatial variation and frequency dependence of intracellular, extracellular, and transmembrane potential are given, the response to sinusoidal currents is used to calculate numerically the response to a step function of current.

Cytoplasm↗
PubMed1979

Cellular site of gastric acid secretion.

Isolated gastric glands of the rabbit were examined both with differential interference-contrast microscopy and with electron microscopy to describe the morphologic correlates of acid secretion. Stimulation of the glands with histamine resulted in the development of intracellular spaces within the parietal cells. A similar transformation was produced by addition of 1 mM aminopyrine, whether the weak base was added in the presence of normal-K+ (5.4 mM) or high-K+ (108 mM) solutions. The intracellular space was compatible with the expanded canaliculus described in stimulated parietal cells. Confirmation that the space produced by histamine is the site of acid secretion was gained by combining fluorescence and interference-contrast methods in the presence of the dye acridine orange, which displays a pH-dependent metachromasia in its emission spectrum. Human gastrin I resulted in an observable discharge of peptic granules.

Acridine Orange↗
PubMed1978

Alloxan uptake by isolated rat islets of Langerhans.

Alloxan inhibits subsequent glucose-induced insulin release from isolated rat islets of Langerhans maintained in vitro. Several agents (D-glucose, D-mannose, 3-0-methyl-D-glucose, caffeine, and cytochalasin B) when present during the alloxan exposure protect against alloxan inhibition of insulin release. To examine the mechanism of alloxan inhibition, the uptake of [2-14C]alloxan was measured in isolated islets. [2-14C]Alloxan was rapidly accumulated by the islets in a time- and temperature-dependent manner. The radio-activity from islets incubated with [2-14C]alloxan was isolated and shown by thin layer chromatography to comigrate with alloxan and alloxanic acid, an alloxan decomposition product. As no uptake of radioactivity occurred in the presence of medium containing the radioactive decomposition product, it was concluded that alloxan enters the intracellular space of the islet and undergoes a subsequent internal decomposition. Some of the protective agents (3-0-methyl-D-glucose, caffeine, and cytochalasin B) partially inhibited alloxan uptake, whereas others (D-glucose and D-mannose) increased the uptake of alloxan. These and other results suggest that the experimental agents do not provide protection against alloxan inhibition by preventing the entry of alloxan into the intracellular space of the islet. The possibility of D-glucose and alloxan competing for a common binding site on the cell membrane is discussed.

Alloxan↗
PubMed1978

Importance of the plasma refilling rate in the genesis of hypovolaemic hypotension during regular dialysis and controlled sequential ultrafiltration-haemodialysis.

The effects of ultrafiltration (UF) on plasma volume (PV) have been studied in eight patients using regular dialysis (RD) and controlled sequential ultrafiltration-haemodialysis (CSU) performed with a Rhodial 75 dialysis system. For a given value of UF the reduction of PV is determined by the plasma refilling rate. During CSU ultrafiltration induces a rapid increase in oncotic pressure without decreasing plasma osmolality. The high plasma refilling rate which can reach 1500 ml/hr allows moderate hypovolaemia despite high rates of UF and contributes to the usual good clinical tolerance of CSU. During RD a rapid decrease in plasma osmolality contributes to a water shift from the vascular space towards the interstitial and intracellular spaces and severe hypovolaemia can occur despite moderate ultrafiltration. CSU offers an adequate treatment for sodium overloaded patients with hypervolaemia, but is of no benefit in routine conditions.

Humans↗
PubMed1978

[Metabolic unit in the microcirculatory system of the exocrine part of the pancreas].

Metabolism between exocrine pancreocytes and blood is mediated with the participation of the metabolic section of the microcirculatory system. It includes: blood capillaries, pericapillary space, intracellular gaps and metabolite distributional complex (basal-lateral folds of pancreocytic plasmolemma). As demonstrated morphological and histochemical changes developed in exocrine pancreocytes and in the metabolic section of the pancreatic gland at different stages of the secretory cycle, interconnections between them are complex and dynamical. All the elements of the metabolic section undergo a certain reconstruction adequate to functional state of pancreocytes. Metabolism between glandular cells and the vascular bed is regulated by structural reconstruction of pancreocytic plasmolemma. A certain functional specialization in plasmolemmic folds is noted: basal-lateral folds regulate transport between pericapillary space and intracellular gaps, while the main function of the lateral folds is to transport substances by means of pinocytosis.

Animals↗
PubMed1975

In vivo studies on the metabolism of hexanedioic acid.

1. Using the combined gas-liquid chromatography-mass spectrometry technique it was shown that ketotic patients excreted up to 273 mg of hexanedioic acid daily in their urine, whereas serum samples from these patients contained only trace amounts of this acid. Healthy humans excreted 2-5 mg daily. Hexanedioic acid was not detectable in normal serum. 2. An experiment with the infusion of large amounts of 3-hydroxybutyrate into a dog indicated that the increased urinary hexanedioic acid excretion in ketosis is not due to a competition between 3-hydroxybutyrate and hexanedioic acid for the same renal reabsorption mechanism. 3. [ 1,6-14-C]Hexanedioic acid intravenously injected into a dog was at first distributed in the extracellular space, followed by a partial equilibration with the intracellular space. About 11% of the injected dose was expired as 14-CO2 in 220 min. The maximal 14-CO2 production rate was obtained after about 20 min. In 240 min, 47% of the injected radioactivity was recovered in the urine. The large urinary excretion of labeled hexanedioic acid observed in the presence of only trace amounts in serum, showed that the high excretion by ketotic patients of the dicarboxylic acid may be explained without postulating an exclusive renal synthesis for hexanedioic acid.

Adipates↗
PubMed1978

On the ultrastructure of modified Sertoli cells in the terminal segment of seminiferous tubules in the boar.

The seminiferous tubules are linked to the tubuli recti by a short terminal segment which is lined by a single layer of modified Sertoli cells whose long cytoplasmic processes occlude the lumen and form a plug-like structure in the 'receptacle. The main features of the modified Sertoli cells are: enormous numbers of microtubules and microfilaments, many crystalloids, abundance of rough endoplasmic reticulum, and paucity of smooth endoplasmic reticulum. The intercellular spaces are considerably dilated, and the cells posses intracellular spaces having well developed microvilli. Degenerated spermatozoa were seen engulfed by the modified Sertoli cells. Desmosome-like devices and tight junctions were observed joining adjacent cells. The configuration of the epithelium and the fine structure of the cells of the terminal segment are discussed in relationship to their possible roles as modifiers of the seminiferous tubule fluid and as regulators of fluid reflux from the rete testis into the seminiferous tubules.

Animals↗
PubMed1978

Potassium efflux in heart muscle during activity: extracellular accumulation and its implications.

1. Extracellular K+ activity and transmembrane potential were simultaneously monitored with a K+-selective micro-electrode placed in the extracellular space and a standard KCl-filled micro-electrode in the intracellular space of the frog ventricular muscle. 2. K+ was found to accumulate during activity and had the approximate magnitude and time course to account for the measured membrane depolarization. 3. The magnitude of the K+ accumulation depended on the frequency of stimulation, diameter of the muscle and temperature of the bathing solution. 4. The time constants of accumulation and decay were dependent only on the diameter and the temperature of the strip. A Q10 of 2 was measured for the decay of accumulated K+. 5. Double barrelled K+-electrodes were used to monitor the change in K+ activity accompanying a single action potential, since the reference barrel allowed for rapid compensation of the electrical potential fluctuations encountered in the subendothelial space. 6. K+ accumulated continuously during the plateau to a level which increased external K concentration by about 1 mM. This increase in the subendothelial space corresponds to about 1-3 muA/cm2 or 10-30 pmole/cm2-sec-1 of net K+ efflux. These values are at least an order of magnitude larger than required to discharge the membrane capacitance. 7. There is no direct relation between action potential duration and rate of development or magnitude of K+ accumulation during that action potential. 8. Increase in the external K concentration, while shortening the action potential and depolarizing the membrane, does not lead to an increased rate of accumulation of K+. The presence of Ni2+, on the other hand, prolongs the action potential and decreases the rate of K+ accumulation. 9. The results suggest that there is a substantial and continuous efflux of K+ during the action potential, which sums during rapid beating, resulting in membrane depolarization and alteration of action potential duration. The change in action potential duration in response to rate may be caused by alteration of EK in the local micro-environments.

Action Potentials↗
PubMed1977

Ultrastructural pattern of acetylcholinesterase distribution in the cerebellar cortex of the quail.

The ultrastructural localization of acetylcholinesterase (AChE) was studied in the cerebellar cortex of the quail by means of histochemical method. The greater amount of AChE was detected at leve of the molecular layer in the intracellular spaces between parallel fibers and between parallel fibers and dendritic terminals. Many neurons showed intracellular localization of enzyme activity: the AChE positive neurons were all Golgi cells, most stellate the basket cells and different aliquots of Purkinje and granule cells. The enzymatic activity was usually localized in the cisternae of endoplasmic reticulum, in the nuclear envelope (but this last localization was not present in Purkinje cells- and sometimes in the Golgi apparatus; reaction granules were usually scarce in the different dendritic branches ramifying in the molecular layer. On the basis of the ultrastructural pattern of AChE distribution, some considerations are developed on the methodological aspects concerning the reliability of histochemical methods, the differences recorded at light and electron microscope level, the problems related to extracellular localization of enzyme, the difficulty of establishing a precise correlation between AChE localization in a cerebellar neuron and its possible cholinergic and/or cholinoceptive nature.

Acetylcholinesterase↗