Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Intracellular Fluid”

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 325 records · Page 18Linked to original sources
PubMed1993

Intracellular glutamine concentration does not decrease in all muscles during sepsis.

The concentrations of glutamine and other amino acids were measured in plasma and intracellular fluid of soleus and extensor digitorum longus (EDL) muscles of rats 4, 8, and 16 hr after induction of sepsis by cecal ligation and puncture or after sham operation. Previous studies have shown that muscle protein breakdown is greatly increased in EDL, but not in soleus muscle, in this sepsis model. Corresponding to previous observations of protein breakdown in sepsis, muscle glutamine was markedly depleted (< 50%) in EDL by sepsis, while no significant fall in glutamine concentration in soleus was observed. Changes in muscle glutamine concentration in sepsis could not be attributed to changes in the precursor of glutamine, glutamic acid. Data were examined for changes consistent with hypothesized alterations in glutamine transport. Correlations among glutamine and other amino acids in muscle, histidine in particular, were consistent with a sepsis-induced alteration in activity of the sarcolemmal glutamine transporter, system Nm. These results thus strengthen the proposed connection between muscle glutamine content and muscle protein metabolism under catabolic conditions.

Amino Acids↗
PubMed1999

Perilipins, ADRP, and other proteins that associate with intracellular neutral lipid droplets in animal cells.

Although all animal cells package and store neutral lipids in discrete intracellular storage droplets, there is little information on the molecular processes that govern either the deposition or catabolism of the stored lipid components. Studies on adipocytes have uncovered the perilipins and ADRP, related proteins that appear to be intrinsic to the surfaces of intracellular lipid storage droplets. We discuss the properties, distribution, localization, and potential functions of these proteins, as well as those of vimentin and the recently-described 'capsular' proteins, in lipid storage and metabolism.

3T3 Cells↗
PubMed2001

Intracellular trafficking and turnover of phosphatidylinositol 3-phosphate.

Phosphatidylinositol 3-kinases (PI 3-kinases) regulate cellular functions through the 3'-phosphorylation of phosphatidylinositol (PI) and its derivatives. The PI 3-kinase product phosphatidylinositol 3-phosphate [PI(3)P] functions to recruit and activate effector proteins containing FYVE zinc finger domains. These proteins have various functions in endocytic membrane trafficking, cytoskeletal regulation and signal transduction. In order to understand the function of FYVE proteins, it is essential to study the formation, localisation, trafficking and turnover of PI(3)P. Here we review recent evidence that PI(3)P is formed on early endosomes through the activity of a PI 3-kinase which is recruited by the GTPase Rab5, and that the PI(3)P is subsequently internalised into intralumenal vesicles of multivesicular endosomes for turnover.

Animals↗
PubMed1993

Cl- channels in basolateral renal medullary membranes: VII. Characterization of the intracellular anion binding sites.

A unique property of basolateral membrane Cl- channels from the mTAL is that the Cl- concentration facing the intracellular aspects of these channels is a determinant of channel open time probability (Po). The K1/2 for maximal activation of Po by Cl- facing intracellular domains of these channels is 10 mM Cl-. The present experiments evaluated the nature of these Cl(-)-interactive sites. First, we found that the impermeant anion isethionate, when exposed to intracellular Cl- channel faces, could augment Po with a K1/2 in the range of 10 mM isethionate without affecting conductance (gCl, pS). Second, pretreatment of the solutions facing the intracellular aspects of the channels with either 1 mM phenylglyoxal (PGO), an arginine-specific reagent, or the lysine/terminal amine reagent trinitrobenzene sulfonic acid (TNBS, 1 mM), prevented the activation of Po usually seen when the Cl- concentration of solutions facing intracellular channel domains was raised from 2 to 50 mM. However, when the Cl- channel activity was increased by first raising the Cl- concentration bathing intracellular channel faces from 2 to 50 mM, subsequent addition of either PGO or TNBS to solutions bathing intracellular Cl- channel faces had no effect on Po. We conclude that the intracellular aspects of these Cl- channels contain Cl(-)-interactive loci (termed [Cl]i) which are accessible to impermeant anions in intracellular fluids and which contain arginine- and lysine-rich domains which can be inactivated, at low ambient Cl- or isethionate concentrations, by interactions with PGO or TNBS.

Animals↗
PubMed1994

Role of vacuolar adenosine triphosphatase in the regulation of cytosolic pH in hepatocytes.

The responses of the cytosolic pH of hepatocytes in suspension to agents affecting the activity of vacuolar adenosine triphosphatase (V-ATPase) and Na/H exchange have been studied. Changes of cytosolic pH were determined both with dual-wavelength excitation (500/440 nm) of the fluorescence of 2',7'-bis-(2-carboxyethyl)-5(and 6)-carboxyfluorescein and from the distribution of 14C-dimethyloxazolidinedione; both methods gave very similar results. Changes of vesicular pH were determined by comparing the fluorescence of fluorescein isothiocyanate-dextran and rhodamine B isothiocyanate-dextran taken up by endocytosis. Nitrate, which inhibits V-ATPase in isolated organelles, induced a concentration-dependent acidification of the cytosol and alkalinization of vesicles, with maximal effects at 25-37.5 mM in each case, indicating that V-ATPase contributes to removal of cytosolic protons. On continued exposure to nitrate, the acidification underwent an amiloride-inhibitable reversal. At the higher concentrations of NO3-, both cytosolic acidification and vesicular alkalinization were reduced or absent. Bafilomycin A1 caused alkalinization of vesicular pH; cytosolic acidification was not observed, possibly because of other ionic exchanges. Recovery of cytosolic pH from an acid load (2 min exposure to 5% CO2) was sensitive to both 25 mM NO3- and to ouabain. The pH dependence of the nitrate effect was tested with media of different pH; the activity was negligible at cytosolic pH 6.2 and rose to a maximum at cytosolic pH 7.3. Treatment of hepatocytes with 0.5-1.0 mM ouabain resulted in an initial alkalinization (0.5-2 min duration) of the cytosol, followed by a spontaneous reversal and, on occasion, further acidification. The alkalinization was blocked by 25 mM NO3-, but not by 25 mM gluconate. The results suggest that the cytosolic alkalinization is caused by a stimulation of H+ uptake by V-ATPase activity. We conclude that V-ATPase make an important contribution to the regulation of the cytosolic pH of hepatocytes.

Amiloride↗
PubMed1986

Proabsorptive properties of forskolin: disposition of glycine, leucine and lysine in rat jejunum.

The effects of forskolin on mucosal cyclic AMP levels and active transport of glycine, L-lysine and L-leucine were studied in rat jejunum in vitro. Furthermore, the effects on lysine and glycine incorporation into mucosal protein and on mucosal cell volume were investigated. Elevation of intestinal mucosal cyclic AMP to threefold control levels by 10 mumol 1(-1) forskolin was accompanied by increased absorption of glycine (+33%), L-leucine (+72%) and L-lysine (+188%), as determined in a three compartment model suitable to measure active transport. Increased intracellular accumulation could be demonstrated for lysine as a transport substrate. Accordingly, using a dual label method, calculated values for uphill transport of lysine at the site of the brush border membrane were markedly enhanced. Forskolin up to 10 mumol 1(-1) had no effects on the fraction of lysine or glycine incorporated into TCA-precipitable proteins of jejunal absorptive cells. Serosal to mucosal transfer, as well as basolateral entry into mucosal cells remained unchanged for all three amino acids. Likewise, intracellular fluid space, calculated from distribution spaces for 14C-inulin and 3H2O as well as the response of cellular volume to an osmotic gradient were not affected by forskolin. As comparable stimulatory effects of forskolin on active hexose transport were reported earlier, it is suggested that forskolin - known to inhibit sodium-coupled fluid absorption - may stimulate active transport by enhancing sodium availability for sodium dependent intestinal cotransporters in general.

Animals↗
PubMed1975

Effects of monovalent cations on cardiac Na+, K+-ATPase activity and on contractile force.

The relationship between Na+, K+-ATPase inhibition by monovalent cations and their inotropic effect was studied in guinea pig hearts. The activity of partially purified cardiac enzyme was assayed in the presence of 5.8 mM KC1 and either 20 or 150 mM NaCl. Rb+ and Tl+ inhibited Na+, K+-ATPase activity, the magnitude of the inhibition by these cations being greater in the assay media containing lower Na+ concentrations. Tl+ produced a dose-dependent inhibition of Na+, K+-ATPase activity in the presence of 20 mM Na+ and 75 mM K+, a cationic condition similar to that of intracellular fluid. Other monovalent cations such as K+, Cs+, NH4+, Na or Li+ produced essentially no effect on the Na+, K+-ATPase activity or slightly stimulated it. In left atrial strips stimulated with field electrodes and bathed in Krebs-Henseleit solution (5.8 mM K+ and 145 mM Na+), addition of Cs+ failed to alter the isometric contractile force significantly. NH4+ and K+ caused a transient positive inotropic effect which was partially blocked by propranolol. The positive inotropic response to K+ was followed by a negative inotropic response. Rb+ produced a sustained, dose-dependent inotropic response reaching a plateau at 1-2 min, whereas Tl+ produced a dose=dependent positive inotropic effect which developed slowly over a 30-min period. The positive inotropic effects produced by Rb+ and Tl+ were insensitive to propranolol pretreatment. Concentrations of Tl+ and cardiac glycosides which produce similar inotropic effects appear to cause the same degree of Na+-pump inhibition. The onset of the positive inotropic response to Rb+ or Tl+ was not dependent on the number of contractions which is in contrast to the cardiac glycoside-induced inotropic response. Substitution of 20 mM LiCl for an equimolar amount of NaCl in Krebs-Henseleit solution produced a significantly greater inotropic response than that observed when sucrose was substituted for NaCl. It appears that, among monovalent cations, only sodium pump inhibitors produce a sustained positive inotropic response.

Adenosine Triphosphatases↗
PubMed1994

Non-invasive conductivity technique to detect changes in haematocrit: in vitro validation.

An on-line haematocrit measurement in extracorporeal circuits might be useful under some clinical circumstances (e.g. haemodialysis or cardiac surgery). As no such measurement exists, a device has been developed that makes it possible to detect haematocrit (Ht) continuously without a loss of blood. It is a multi-frequency system for the detection of electrical conductivities. The aim of this study was to investigate whether this device can measure Ht alterations properly. Ht alterations were induced by adding pure mannitol and 20% mannitol to fresh human blood. Furthermore, the effect of both mannitol substances on the intracellular ion content, intracellular conductivity and Ht were investigated. Alternations in Ht were established by the addition of 1000, 800, 600, 400, 200 and 0 mg of pure mannitol to 10 ml of fresh human blood, and 3.0, 2.5, 2.0, 2.0, 1.5, 1.0, 0.5 and 0 ml of 20% mannitol to fresh human blood until a total volume of 10 ml was achieved. Although their effects were significantly different, pure mannitol and 20% mannitol both caused a reduction in mean cellular volume, and thus in Ht. A highly significant correlation was found between Ht and intracellular conductivity (r = 0.90, p < 0.001). In addition to these effects, addition of pure mannitol and 20% mannitol had different effects on the intracellular ion content. Pure mannitol caused an increase in intracellular ion content due to a transcellular ion shift, whereas 20% mannitol induced a decrease. From this study, it can be concluded that the multi-frequency conductivity method observes changes in Ht (and intracellular fluid volume) in an accurate manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Electric Conductivity↗
PubMed1998

CT analysis of the use of the electrical impedance technique to estimate local oedema in the extremities in patients with lymphatic obstruction.

The aim of the study is to establish the validity of the use of the electrical impedance technique for estimating local oedema in extremities through comparison with computed-tomography (CT) analysis. Eight healthy women (group 1) and nine women with unilateral leg oedema following chronic lymphatic obstruction (group 2) are examined sequentially utilising both methods. 'Equivalent resistivities' of extra- and intracellular fluid (RE and RI) are measured in the leg's upper portion with a multi-frequency impedance meter, and seven CT slices are taken in the same leg segments. In each slice, the ratios of interstitial fluid to subcutaneous tissue and to muscle are calculated using the CT number of plasma for interstitial fluid, and CT numbers of subcutaneous tissue and muscle of group 1 for 'normal' tissues. A decrease in RE and an increase in RI/RE, indicating extracellular fluid increase, are observed in oedematous legs in group 2 when compared with the left legs in group 1. Correspondingly, an increase in the ratios of interstitial fluid to subcutaneous tissue area and to total cross-sectional area is observed in the oedematous legs when compared with those of normal legs in CT analysis. Thus the multi-frequency impedance technique is effective in detecting local oedema in extremities.

Adult↗
PubMed1990

Gas supersaturation tolerances in amoeboid cells before and after ingestion of bubble-promoting particles.

Macrophages and other cells are capable of ingesting a variety of solids from their external environment. When such phagocytic processes occur in animals, they can lead to phagocytosis from the respiratory or the digestive tract of particles containing minute air emobli that may serve as bubble nuclei upon exposure of the animal to conditions of gas supersaturation. To test whether this is possible, gas supersaturation tolerances were determined for murine macrophages and macrophage-like tumor cells, and for cells of the slime mold Dictyostelium discoideum, before and after phagocytosis of particles that were effective in inducing bubble formation in nitrogen-supersaturated aqueous suspensions. After phagocytosis, the ability of the particles to induce bubble formation was completely abolished. All three cell types essentially retained their normal high resistance to bubble formation; even nitrogen supersaturations in excess of 150 atm (1.55 x 10(7) Pa) did not lead to internal bubbles. Alterations of the particle surfaces and unique properties of the intracellular fluid appear to be the underlying cause of the extremely high gas supersaturation tolerances observed.

Animals↗
PubMed1998

Calcium metabolism of focal and penumbral tissues in rats subjected to transient middle cerebral artery occlusion.

The present experiments were undertaken to define changes in tissue calcium metabolism in focal and perifocal ("penumbral") tissues following 2 h of transient middle cerebral artery occlusion (MCAO) in rats, induced with an intraluminal filament occlusion technique. The extracellular calcium concentration ([Ca2+]e) was measured with ion-selective microelectrodes in neocortical focus and penumbra. For measurement of total tissue calcium content, tissue samples from these areas were collected and analyzed with atomic absorption spectrometry. During MCAO, [Ca2+]e in a neocortical focal area fell from a normal value of about 1.2 mM to values around 0.1 mM, suggesting translocation of virtually all extracellular calcium to intracellular fluids. Recirculation was accompanied by re-extrusion of calcium within 5-7 min; however, [Ca2+]e never returned to normal but stabilized at about 50% of the control value for the first 6 h, and decreased further after 24 h. In penumbral areas, [Ca2+]e showed the expected transient decreases associated with spreading depression-like (or ischemic) depolarization waves. Recirculation was followed by return of [Ca2+]e towards normal values. In the focus, water content increased from about 79% to about 80.4% at the end of the 2-h period of ischemia. After 2 h and 4 h of recirculation, the edema was aggravated (mean values 81.9% and 81.2%, respectively). After 6 h and 24 h, the edema was more pronounced (83.6% and 83.8%, respectively). In the penumbra, no significant edema was observed until 6 h and 24 h of recirculation. The total tissue calcium content in the focus (expressed by unit dry weight) increased at the end of the ischemia period demonstrating calcium translocation from blood to tissue. After 6 h and 24 h, the content increased two- to threefold, compared with control. Changes in the penumbra were qualitatively similar but less pronounced, and a significant increase was not observed until after 6 h of recirculation. The results suggest that 2 h of MCAO leads to a profound perturbation of cell calcium metabolism. In focal areas, cells fail to extrude the calcium that is gradually accumulated during reperfusion and show massive calcium overload after the first 4-6 h of recirculation. Penumbral tissues show a similar increase in calcium concentration after 6 h of recirculation.

Animals↗
PubMed2001

Effects of 8-cpt-cAMP on the epithelial sodium channel expressed in Xenopus oocytes.

Vasopressin stimulates the activity of the epithelial Na channel (ENaC) through the cAMP/PKA pathway in the cortical collecting tubule, or in similar amphibian epithelia, but the mechanism of this regulation is not yet understood. This stimulation by cAMP could not be reproduced with the rat or Xenopus ENaC expressed in Xenopus oocyte. Recently, it was shown that the alpha-subunit cloned from the guinea-pig colon (alpha gp) could confer the ability to be activated by the membrane-permeant cAMP analogue 8-chlorophenyl-thio-cAMP (cpt-cAMP) to channels produced by expression of alpha gp, beta rat and gamma rat ENaC subunits. In this study we investigate the mechanism of this activation. Forskolin treatment, endogenous production of cAMP by activation of coexpressed beta adrenergic receptors, or intracellular perfusion with cAMP did not increase the amiloride-sensitive Na current, even though these maneuvers stimulated CFTR (cystic fibrosis transmembrane conductance regulator)-mediated Cl currents. In contrast, extracellular 8-cpt-cAMP increased alpha gp, beta rat and gamma rat ENaC activity but had no effect on CFTR. Swapping intracellular domains between the cpt-cAMP-sensitive alpha gp and the cpt-cAMP-resistant alpha rat-subunit showed that neither the N-terminal nor the C-terminal of alpha ENaC was responsible for the effect of cpt-cAMP. The mechanisms of activation of ENaC by cpt-cAMP and of CFTR by the cAMP/PKA pathway are clearly different. cpt-cAMP seems to increase the activity of ENaC formed by alpha gp and beta gamma rat by interacting with the extracellular part of the protein.

Amiloride↗
PubMed2001

Cytocidal effect and DNA damage of nedaplatin: a mathematical model and analysis of experimental data.

PURPOSE: Cell cycle non-specific anticancer agents such as cis-diamminedichloroplatinum(II) are believed to depend linearly on the value of the area under the drug concentration time curve, which is supported by a mathematical model. However, the quantitative non-linear phenomena of both the cytocidal effect and DNA crosslink formation by cisdiammine(glycolato)platinum (nedaplatin) have been shown in vitro. Therefore, we developed a new mathematical model to explain these phenomena. METHODS: We assumed that nedaplatin enters intracellular fluid from medium through simple diffusion to form DNA crosslinks that kill cells. We developed a mathematical model to represent this assumption using differential equations that we then solved using an original computer program. The calculated results were compared with the experimental data. RESULTS: The drug's simple diffusion rate constant, the DNA crosslink formation rate constant, and the crosslink-dependent cell death rate constant in the model were 1.8 x 10(-14) (l h-1), 1.6 x 10(8) (l mol-1/2 h-1), 5.45 x 10(1) (mol-1), respectively. The model fits the experimental results statistically. The model also demonstrated theoretical proof that continuous exposure at a low dose was superior to the short exposure at a high dose seen in published experimental data. CONCLUSIONS: We developed a mathematical model to describe the non-linear pharmacodynamic effect of nedaplatin in vitro. This model may provide a novel drug infusion procedure for cancer patients.

Antineoplastic Agents↗
PubMed1987

Characteristics of lysine transport by isolated rat renal cortical tubule fragments.

The uptake of L-lysine was examined in isolated renal cortical tubules. Lysine was actively taken up by the renal tubule cells isolated from 7-week-old rats. No metabolism of the transported lysine was found. There was no evidence for sodium-dependence of lysine uptake. Concentration dependence studies revealed that the lysine was taken up by one saturable transport system with a Km of 1.66 mmol/l and Vmax of 7 mmol/l intracellular fluid per 10 min. Lysine also entered by a non-saturable pathway. Arginine and ornithine inhibited the initial uptake of lysine. Cystine increased the efflux of lysine from preloaded renal cells via hetero-exchange, indicating that a common system exists for these two amino acids.

Animals↗
PubMed1994

The structural differences between the embryos of viable and nonviable wheat seeds as studied with the EPR spectroscopy of lipid-soluble spin labels.

Dried and hydrated embryos of wheat seeds (viable and nonviable, harvested in 1992 and 1976, respectively) were studied by the EPR method with the use of the spin-labeling technique. Spin label Tempone was used for testing the plasmalemma integrity. It has been demonstrated that the loss of seed viability correlates with the loss of external membrane integrity. Spin-labeled derivatives of stearic acids, 5-doxylstearate I(12.3) and 16-doxylstearate I(1.14), were used to monitor the changes in structural characteristics of embryo cell membranes. The EPR spectra of these spin labels represent the superpositions of at least two signals from the molecules located in domains characterized by different fluidity. The comparison of the EPR spectra from I(12.3) in embryo cells and model systems (total fraction of lipids and purified seed oil) indicates that the majority of spin label molecules is located in the lipid surroundings, while the minor portion of I(12.3) is localized in so-called lipid bodies which contain seed oil. The embryo cells of viable and nonviable seeds differ in the sizes of these 'solid' and 'fluid' intracellular domains. The environment of spin label molecules located in cell membranes of nonviable seeds is more rigid, as compared with that in the membranes of the viable cells. The study of dehydration-rehydration effects has demonstrated that the loss of water causes the restriction of spin label mobility in embryo cells from both kinds of seeds.

Electron Spin Resonance Spectroscopy↗
PubMed1984

Trapping of electro-injected [14C]sucrose by hepatocyte mitochondria: a mechanism for cellular autofiltration?

[14C]Sucrose was introduced, by means of electropermeabilization, into the cytosol of isolated rat hepatocytes to serve as an inert marker of the intracellular fluid. Radioactivity accumulated in mitochondria (as well as in lysosomes) at a rate of 2-3%/h for 4 h of incubation at 37 degrees C, as shown by subcellular fractionation in isotonic density gradients. This unprecedented mitochondrial trapping of a molecule which does not cross most biological membranes points to the possibility that mitochondria participate in some kind of autofiltration of cellular fluid.

Acyltransferases↗
PubMed1991

Effect of paracetamol on mitochondrial membrane function in rat liver slices.

The effect of paracetamol on mitochondrial function was studied using rat liver slices. Changes in the potential of the mitochondrial and plasma membrane were monitored using [3H]-triphenylmethylphosphonium (TPMP+) and [14C]thiocyanate (SCN-) probes, respectively. Liver slices were exposed to 10 mM paracetamol for various time periods (0-360 min) after loading with TPMP+. The release of TPMP+ which correlates with a decrease in the mitochondrial membrane potential became significant after 30 min incubation with 10 mM paracetamol. The change in the mitochondrial membrane potential was shown to be independent of cytochrome P450 activity. No significant change in plasma membrane potential was observed, until the release of lactate dehydrogenase (LDH) had begun, 4 hr after exposure, reflecting the ultimate stages of cell injury by paracetamol. These results suggest that paracetamol elicits a direct effect on the mitochondrial function before cell injury develops and adds further evidence to the role of mitochondria in paracetamol toxicity.

Acetaminophen↗