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Results for “Extracellular Space”

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At least 19 recordsLinked to original sources
PubMed1979

Fractional extracellular space and fractional water content of various rat tissues at different extracellular pH values and in uremia.

At different extracellular pH values fractional extracellular space (calculated from the distribution of 3H inulin) and fractional water content showed no significant differences. 72 h after nephrectomy both variables increased significantly. An exception to this was brain, where fractional extracellular space decreased and total intracellular water increased as a sign of brain oedema.

Animals↗
PubMedDate not supplied

Influence of contractile state on the size of the extracellular space in isolated ventricular myocardium.

A method is described with which the extracellular space of isolated ventricular muscle can be measured accurately and continuously in the same muscle. The size of the extracellular space is shown to vary with the contractile state of the myocardium. Interventions such as quiescence, manganese and acidosis reduce myocardial contractility and increase the size of the extracellular space. Barium, ouabain and hypoxia cause contracture and reduce the size of the extracellular space. These changes should be taken into account when measuring intracellular electrolytes in isolated ventricular preparations.

Acidosis, Respiratory↗
PubMedDate not supplied

Release of enzymes from cells: transport and distribution within the extracellular space.

The distribution in the extracellular space of enzymes released from organ cells was investigated using three models: (1) comparison of enzyme activities in blood plasma and lymph of the ductus thoracicus (dog) and plasma and intestinal lymph (rat); (2) i.v. injection of heterologous, homologous and autologous enzymes in order to increase acutely the activities and to measure the rate constants for the distribution and elimination of the enzymes (rat); or (3) plasmapheresis in order to create an enzyme activity gradient from the interstitial space and to determine the rate constants for the reestablishment of the equilibrium between the extra and intravascular compartments (rat). The results suggest that the enzymes are mainly released into the interstitial fluid and transported via the lymph into the intravascular compartment. From there the enzymes diffuse back into the interstitial compartment and are eliminated by a yet unknown mechanism. Transport of enzymes across the capillary membranes in both directions depends on (1) the permeability of the capillary membranes, which varies from region to region and (2) the molecular seizes of the enzymes.

Animals↗
PubMed1979

Brain extracellular space fixed for electron microscopy.

Adult mammalian brain contains 17--20% extracellular space, but fixatives cause the cellular elements to ingest the extracellular fluid so that the space is reduced to less than 5% with all conventional methods of fixation. This can be prevented by washing out the extracellular fluid with isotonic sucrose, which does not penetrate cells. Subsequent fixation with aldehydes and osmium and conventional processing leads to the preservation of extracellular space in electron micrographs. Extracellular space was found to be unevenly distributed, widely separating some cellular processes while leaving other groups of processes contiguous.

Animals↗
PubMed1977

Age-related change in the neuronal microenvironment: penetration of ruthenium red into extracellular space of brain in young adult and senescent rats.

The volume of the extracellular space, which contributes to the microenvironment of neurons, is diminished in the brains of senescent (as compared to adult) rats and an age-related change in its composition has been hypothesized. To test this hypothesis we have compared the penetration of ruthenium red, a polyanion selectively distributed in the extracellular space, into the dentate gyri of young adult and senescent Fischer 344 rats. Slices of hoppocampal formation were fixed by immersion, first in a glutaraldehyde solution containing ruthenium red, then in a solution of osmium tetroxide containind examined by electron microscopy. Dense particles of ruthenium red reaction product were readily localized in intercellular channels and synaptic clefts and the depth of penetration of ruthenium red in 25-month-old rats, as compared with 3-month-old animals, was found. These data indicate an age-related change in the charge density of the intercellular channels in the dentate gyrus of 25-month-old rats. They suggest a primary age-related change in the charg density of extracellular macromoledules, presumed to be primarily glycosaminoglycans, with a consequent change in water binding capacity and volume of the extracellular space.

Aging↗
PubMedDate not supplied

[A synthetic review on the cerebral extracellular space evaluated by biochemical procedures (author's transl)].

The Authors present a synthetic review on the problem of the cerebral extracellular space evaluated by biochemical procedures. The studies in vitro are numerous, focused on various aspects, such as the choice of the marker, the influence of temperature, and that of the chemical composition of incubation media, the regional heterogeneity of the brain, and so on; it has been observed that inulin, which is the most commonly employed marker, gives an extracellular space of about 40-66%, whereas other markers give values higher than 45%; the variability of values depends on various experimental factors. The studies in vivo present some methodological difficulties due to the existence of the brain barrier; the most reliable procedure appears that of the continuous perfusion of the marker into the cerebrospinal fluid associated with a simultaneous intravenous perfusion; this procedure gives quantitative estimates of extracellular space of about 14-30%. Taking into account that other experimental methods (such as the morphological and the electrophysiological) give lower values, respectively of 5-20% and 18-25%, the Authors found that it should be possible to agree about an average value of cerebral extracellular space of 15-20%. This appears to be of some relevance especially in studying the pathological problems of the brain, and particularly cerebral edema.

Brain↗
PubMed1979

Potassium activity in photoreceptors, glial cells and extracellular space in the drone retina: changes during photostimulation.

1. A double-barrelled potassium-sensitive micro-electrode was developed that was fine enough to record intracellular electrical potentials and potassium activities (aK) in the drone retina. 2. aK was measured in the photoreceptor cells, in the pigment (glial) cells, and in the extracellular space, in the superfused, cut, retina. The effect of photostimulation was studied: 20 msec light flashes, intense enough to evoke receptor potentials of maximum amplitude were presented, 1/sec, in a train lasting about 2 min. 3. In photoreceptors with membrane potentials greater than or equal to 50 mV aK in the dark was 79 mM, S.D. = 27 mM, n = 11. During photostimulation aK fell by 21.5 +/- 9.5 mM with a half-time of 30 +/- 22 sec. (A tentative conversion from activities to free concentrations can be made by taking the activity coefficient as 0.70 its value in the Ringer solution). 4. In pigment cells with membrane potentials greater than or equal to 50 mV, aK in the dark was 52 mM, S.D. = 13 mM, n = 11. During photostimulation aK increased by 14 +/- 5 mM. 5. In the extracellular space aK increased during photostimulation with a mean half-time of less than 1.3 sec to a maximum (mean value 14 mM, S.D. = 8.4 mM, n = 22), and then fell to a plateau. 6. It is estimated from the anatomy that the photoreceptors occupy approximately 38% of the total volume of the retina, the pigment cells 57%, and extracellular space 5%. Hence, it seems possible that during photostimulation nearly all the net loss of potassium from the photoreceptors is temporarily stored in the pigment cells. 7. Recordings were made in the extracellular space of the intact animal by passing the electrode through a hole in the cornea. The mean aK in the dark was 7.7 mM, S.E. = 0.4 mM, n = 22. In the superfused retina, aK in the dark was 6.3 mM, S.E. = 0.7 mM, n = 22, even though aK in the Ringer solution was 2.2 mM. Increasing the aK of the Ringer solution to 7.0 mM had no apparent effect on aK in the extracellular space at depths greater than 20 micron. 8. In the intact animal the amplitude and time course of the change in extracellular aK evoked by the standard pattern of photostimulation were within the range observed in the superfused preparation.

Animals↗
PubMed1979

Discrepancies in the extracellular space of sympathetic ganglia measured using different isotopes of mannitol and sucrose.

The extracellular space of rat superior cervical ganglia in vitro was measured using mannitol and sucrose labelled with tritium and carbon-14. The volumes of distribution of the 3H-labelled derivatives, especially [3H]mannitol, exceeded those of the 14C-derivatives. The divergence increased with increasing lengths of incubation. Thus, after 30 min incubation, 'spaces' (ml . g-1) were: [14Cu]mannitol, 0.407; [3H]mannitol 0.447; [14C]mannitol, 0.458; [3H]mannitol, 0.645; [14C]sucrose, 0.430; [3H]sucrose, 0.497. Using thin layer chromatography, it was shown that an average of 22% of the label in ganglia incubated for 120 min with [3H]mannitol, but only 4% with [14C]mannitol, was not associated with the parent compound. Both [3H]- and [14C]sucrose appeared to be metabolized by 11%. It is concluded that mannitol and sucrose can be metabolized in isolated ganglia and that this may lead to substantial errors in estimating the extracellular space, particularly when [3H]markers are used.

Animals↗
PubMed1979

Membrane potential and ion concentration stability conditions for a cell with a restricted extracellular space.

For an isolated membrane, the resting (zero current) potential is stable is the slope conductance is positive, and is unstable if the slope conductance is negative. Recent work suggests that the properties of many preparations are influenced by the presence of an extracellular space that is not in good diffusive contact with the bulk extracellular fluid. Ionic current flow across the membrane changes the ion concentrations in this space. These concentration changes affect the stability of the membrane potential. Even if the slope conductance is negative, the presence of the extracellular space can confer stability on the resting potential. Conversely, even if the slope conductance is positive, the extracellular space can produce instability of the resting potential. Evaluation of the relevant parameters for cardiac Purkinje fibres, from published experimental data, suggests that concentration changes in the extracellular space may play a significant role in determining when an action potential is initiated.

Animals↗
PubMed1979

Extracellular space, water, and ion concentration in the hypertrophied rat myocardium.

Extracellular space (ECS), water, and intracellular ion concentration were determined in the normal and hypertrophied rat myocardium. Theoretical measurements of myocardial ECS based on a mathematical model (9.31%) closely approximated the observed results in the normal myocardium (12.8%) and hypertrophied myocardium (11.7%). Observed results confirmed theoretical considerations of no change in ECS with hypertrophy. ECS and water content were higher in the right ventricle than the left ventricle, but intracellular electrolytes remained unchanged. Myocardial hypertrophy did not alter these relationships.

Animals↗
PubMed1979

Extracellular space of frog skeletal muscle in vivo and in vitro: relation to proton magnetic resonance relaxation times.

1. The Na and Cl distribution spaces of freshly isolated frog muscles are 16.7 and 12.6%, respectively. These values increase to 25.6 and 23.3%, respectively, on incubation. 2. The extracellular components of both Na and Cl efflux curves are significantly smaller in freshly isolated muscles (approximately 12%) than in incubated muscles (approximately 18%). The fast exchanging A component of the extracellular space is increased more by incubation than the more slowly exchanging B component. 3. The proton magnetic resonance (p.m.r.) transverse relaxation curve for the water of freshly isolated frog muscles did not show the long, slowly relaxing tail present in curves from muscles incubated in Ringer solution. 4. When muscles were incubated in hypertonic solutions the p.m.r. transverse relaxation curves could be resolved into three components whose sizes were consistent with the components present in the sodium and chloride efflux curves. The non-exponentiality of the p.m.r. transverse relaxation curve therfore appears to arise from water in both the A and B extracellular compartments of muscle. 5. Efflux analysis indicated that the cellular Na content of both freshly isolated and incubated frog muscle is similar to that predicted by others (Lev, 1964; Armstrong & Lee, 1971; Lee & Armstrong, 1974) from measurements of intracellular Na ion activity using Na-sensitive micro-electrodes. The remainder of the tissue Na was found in the more rapidly exchanging extracellular compartments. The results of these experiments are inconsistent with the presence of a substantial fraction of bound Na in frog muscle. 6. These experiments show that muscle extracellular space is smaller in vivo than in vitro. Efflux analysis is suggested as the most accurate method of assessing extra-cellular components.

Animals↗
PubMed1977

[Banded filamentous associates in the intra- and extracellular space in connection with collagen degradation (author's transl)].

Banded fibrous associates are described in the extracellular space of connective tissue from human endometrium, Ehlers-Danlos syndrome and of tendon rupture. In the cases of morbus Dupuytren these associates are also found as intracellular inclusions. The banded structures are interpreted as states of an enzymatically induced degradation of collagen in correlation with Type-III collagen.

Adult↗
PubMed1979

Extracellular space determination in rat small intestine by using markers of different molecular weights.

The apparent extracellular space (ECS) of rat jejunum, everted and cannulated "in vitro", has been measured by using extracellular markers of different molecular weights. The markers used were two polyethyleneglycols, 14C and 3H labelled (14C-PEG MW 4000 and 3H-PEG MW 900) and 3H-sucrose. The ECSs for the mucosal and serosal sides have been separately determined throughout the time course, and it has been found that the two spaces are identical when PEG 4000 was used but the serosal ECS is almost the double when using PEG 900. The serosal ECS determined with sucrose is four times as big as the mucosal ECS. It seems reasonable to conclude that the best marker for the measure of total apparent ECS is sucrose, placed in the serosal compartment, taking into account that the mucosal ECS is four times smaller than the serosal one. All the markers used reach equilibrium with ECS, more rapidly in the mucosal than in the serosal ECS. Finally, by comparing cell water and cell Na concentrations, one observes that there is a statistical difference between the results obtained by using PEG 4000 as an extracellular marker and those obtained with sucrose.

Animals↗
PubMed1978

Blood volume and extracellular space (ECS) of the whole body and some organs of the rat.

Methods are described for estimation of blood volume and extracellular space (ECS) in the whole body and in some organs with 51Cr, 14C-thiocyanate and 3H-inulin. A mean blood volume of 47 ml/kg, a thiocyanate space of 350 ml/kg and a inulin space of 288 ml/kg were determined in the rat. The corresponding values of organs are shown in figures 1--3.

Animals↗
PubMedDate not supplied

[Effect of glucocorticoids on electrolyte excretion after expansion of the extracellular space].

The influence of glucocorticosteroids (cortisone, hydrocortisone, prednisone, dexamethasone, and triamcinolone) on the volumetric natriuresis was studied in experiments on rats. Natriuresis proved to increase considerably after the widening of the extracellular space, and exceeded sodium excretion in control animals after a similar increase of the fluid volume in control animals. Intensification of the natriuretic response to the increase of the extracellular fluid volume against the background of glucocorticoids apparently occurred as a result of production or activation under the influence of these hormone of the natriuretic factor.

Animals↗
PubMed1977

Paracellular permeability of extracellular space markers across rat jejunum in vitro. Indication of a transepithelial fluid circuit.

1. The characteristics of [51Cr]EDTA, [3H]methoxyinulin ([3H]MI), [14C]polyethylene glycol-4000 ([14C]PEG), and [3H]mannitol as markers of the extracellular space (e.c.s.) of isolated mucosa from the rat small intestine have been examined. 2. Unidirectional transmural fluxes across the rat jejunum of [3H]MI, [14C]PEG and [3H]mannitol have been measured in the absence of glucose or in the presence of 28 mM glucose. 3. Assuming that [14C]PEG does not enter the cells, [51Cr]EDTA and [3H]mannitol seem to have access to approximately 50 and 90% of the intracellular water respectively. 4. The commercially availabel [3H]MI had access to a space which exceeded th [14C]PEG space by 10%. Upon purification by gel filtration the high molecular weight fraction of the [3H]MI provided estimates of the e.c.s. identical with the estimates obtained with [14C]PEG. 5. For all the markers used the e.c.s. estimates remained constant between the 40th and 80th min of incubation. 6. In the absence of glucose the transepithelial net fluxes of each of the different markers were zero. In the presence of 28 mM glucose the serosato-mucosa fluxes of all markers were dramatically increased. The ratio between the serosa-to-mucosa and the mucosa-to-serosa fluxes increased in the order [3H]mannitol greater than [3H]MI greater than [14C]PEG. 7. The effect of glucose on the flux ratio of the marker substances suggests that glucose-induced net water transport to the serosa side of the gut wall represents the difference between a transcellular net water transport to the serosal side and a significant paracellular net water transport through the lateral intercellular spaces to the mucosal solution.

Animals↗