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PubMed1959

Depletion of reserve protein from extravascular extracellular fluid; C14 labeling of plasma proteins in dogs after plasmapheresis.

During protein depletion produced by plasmapheresis and a very low protein diet there is a proportionately greater decrease in extravascular, extracellular fluid protein than in plasma protein. A shift in the normal ratio of protein in these 2 compartments, approximately 1 to 1 in the dog, to over 2 to 1 as a result of depletion indicates an important, labile source of reserve protein for the plasma in the interstitial fluids. This reserve source is limited since a maximum drop of 50 per cent in the total exchangeable pool and of 75 per cent in the extravascular, extracellular protein occurred after both shorter and longer periods of depletion. Under the rigid conditions of these experiments additional plasma protein removal was associated with loss of weight despite adequate caloric intake. Investigation of the status of the interstitial fluid proteins in other conditions associated with disturbed protein metabolism seems warranted.

Animals↗
PubMed1979

Extracellular fluid of the kidney preserved by the Collins technique.

Hilar drainage fluid of dog kidneys was analyzed as an approximation to renal extracellular fluid after preservation by flushing with chilled high K-low Na solution (Collins C4) followed by ice-cold storage for 24 and 48 hr in a bath of flushing medium. Compared with the medium, Na and Cl were increased to 30 mM/liter and K decreased slightly to 93 mM/liter. Glucose decreased, whereas lactate, lactic dehydrogenase, and creatine phosphokinase increased by significant amounts in both the drainage fluid and bath. The inulin space of the undrained kidney average 37% of wet weight. Calculated intracellular Na and Cl concentrations averaged 50 and 37 mM/kg cell water while K remained within normal limits. A significant fraction of red blood cells retained during initial flushing entered the effluent during storage. Bath and effluent composition of a human cadaver kidney approximated those of a dog.

Animals↗
PubMed1994

Assessment of refill and hypovolaemia by continuous surveillance of blood volume and extracellular fluid volume.

During renal replacement therapy hypovolaemia due to ultrafiltration (UF) may, when not sufficiently counteracted by refill from the interstitium, result in hypotension. Combining two recently developed methods the haemodynamic process of refill was studied in order to find characteristics featuring hypotension. Relative blood volume (BV) and extracellular fluid volume (EFV) were measured continuously in 40 stable haemodialysis patients by means of an optical and a conductivity technique respectively. Regarding their postdialytic (PD) EFV the patients were divided into three groups: normohydrated (N, n = 20), dehydrated (D, n = 11) and overhydrated (O, n = 9). Significant differences between the groups were assessed in BV decrease (after 2 h until the end of treatment P < 0.05 and after 3 h P < 0.01), EFV decrease (after 3 h P < 0.05) and occurrence of hypotensive episodes (N,5; D,7; O,none; P < 0.01). During the entire session the speed of BV decrease was significantly higher in hypotensive patients (H) than in non-hypotensive patients (non-H). At the moment of hypotension (after 141 +/- 49 min) residual BV was less (P < 0.0005) in H (87.7 +/- 5.2%) than at the corresponding moment in non-H patients (96.5 +/- 4.0%). PD BV and PD EFV, both expressed as a percentage of the starting value, correlated significantly (r = 0.63, p < 0.005) and UF-volume (differences between the groups were not significant) correlated to EFV decrease (r = 0.45, P < 0.005). In conclusion, the combination of both non-invasive methods elucidates the pathophysiology of UF-induced hypotension and provides a means of reducing dialysis morbidity. The influence of tissue hydration state on these variables has been shown.

Aged↗
PubMed2003

Deposition of bone-like apatite on silk fiber in a solution that mimics extracellular fluid.

The fabrication of apatite-organic polymer hybrids is one of several attractive methods for the development of biomaterials as a substitute for bone. Such materials have both bone-bonding ability and mechanical properties analogous to natural bone. The biomimetic process has focused attention on fabricating such hybrids, where bone-like apatite is deposited on an organic polymer surface in solutions that mimic physiological conditions. In this process, a bone-like apatite layer can be coated onto organic substrates either by using a simulated body fluid (SBF) with ion concentrations nearly equal to those of human extracellular fluid, or by using fluids that are supersaturated with respect to apatite at ambient conditions. In this study, we investigated the ability of natural silk and its related materials to facilitate apatite deposition under biomimetic conditions. Cloths made of raw silk or normal silk fibers were soaked in 1.5SBF, which has 1.5 times the ion concentration of SBF. Sericin film, which is made from an extract of degummed raw silk, was soaked in 1.5SBF. The cloth and the film soaked in 1.5SBF then were characterized by scanning electron microscopic (SEM) observation, energy dispersive X-ray microanalysis (EDX), and thin-film X-ray diffraction (TF-XRD). Apatite deposition was observed on the surface of cloth made from raw silk fiber after it was soaked in 1.5SBF, but it was not observed on cloth made from normal silk fibers. The apatite deposition on the raw silk fiber cloth was accelerated when the fibers were subjected to treatment with CaCl(2) solution at a concentration of at least 1 kmol/m(3) before immersion in 1.5SBF. Apatite deposition also was observed on the sericin film after the film was soaked in 1.5SBF for 7 days. These results indicate that apatite deposition on raw silk cloth is attributable to the catalytic effect of sericin because the surface of raw silk consists of sericin whereas that of normal silk contains fibroin. The deposition of the apatite and its crystal growth are accelerated by the presence of calcium ions on the sericin after treatment with CaCl(2) solution. Thus, sericin on natural silk fiber has the potential to facilitate apatite deposition and can be useful as a polymer material in the fabrication of hybrid materials analogous to bone through biomimetic processes.

Apatites↗
PubMed2002

Glial uptake of neurotransmitter glutamate from the extracellular fluid studied in vivo by microdialysis and (13)C NMR.

Glial uptake of neurotransmitter glutamate (GLU) from the extracellular fluid was studied in vivo in rat brain by (13)C NMR and microdialysis combined with gas-chromatography/mass-spectrometry. Brain GLU C5 was (13)C enriched by intravenous [2,5-(13)C]glucose infusion, followed by [(12)C]glucose infusion to chase (13)C from the small glial GLU pool. This leaves [5-(13)C]GLU mainly in the large neuronal metabolic pool and the vesicular neurotransmitter pool. During the chase, the (13)C enrichment of whole-brain GLU C5 was significantly lower than that of extracellular GLU (GLU(ECF)) derived from exocytosis of vesicular GLU. Glial uptake of neurotransmitter [5-(13)C]GLU(ECF) was monitored in vivo through the formation of [5-(13)C,(15)N]GLN during (15)NH(4)Ac infusion. From the rate of [5-(13)C,(15)N]GLN synthesis (1.7 +/- 0.03 micromol/g/h), the mean (13)C enrichment of extracellular GLU (0.304 +/- 0.011) and the (15)N enrichment of precursor NH(3) (0.87 +/- 0.014), the rate of synthesis of GLN (V'(GLN)), derived from neurotransmitter GLU(ECF), was determined to be 6.4 +/- 0.44 micromol/g/h. Comparison with V(GLN) measured previously by an independent method showed that the neurotransmitter provides 80-90% of the substrate GLU pool for GLN synthesis. Hence, under our experimental conditions, the rate of 6.4 +/- 0.44 micromol/g/h also represents a reasonable estimate for the rate of glial uptake of GLU(ECF), a process that is crucial for protecting the brain from GLU excitotoxicity.

Acetates↗
PubMed1975

Effects of extracellular fluid volume contraction and expansion on the bicarbonaturia of parathyroid hormone.

To evaluate the effect of extracellular fluid volume alterations on the bicarbonaturia of parathyroid hormone, thyroparathyroidectomized dogs were made alkalotic and volume-contracted or expanded through hemodialysis. Clearance studies were performed before and after infusion of purified bovine parathyroid extract (PTE). Glomerular filtration rate and blood bicarbonate concentrations were kept constant throughout the experiments. A significant increase in fractional bicarbonate excretion was observed following PTE infusion in both the volume-contracted (8.67 +/- 3.25 to 14.70 +/- 3.63%, P less than 0.010) and the volume-expanded state (22.80 +/- 3.04 to 37.26 +/- 3.38%, P less than 0.050). It is concluded that PTE decreases reabsorption of bicarbonate independent of the volume state of the animal.

Alkalosis↗
PubMed1984

Studies on the glomerular filtration rate and extracellular fluid volume in rhesus monkeys infected with Plasmodium knowlesi.

The glomerular filtration rate (GFR) and the extracellular fluid volume (ECV) were determined in 5 rhesus monkeys infected with P. knowlesi in comparison with 6 control monkeys by using 51Cr-EDTA. As the disappearance curve of the radioactivity showed a close fit to a double exponential equation, the data was therefore analysed by an open 2-compartment system. Results in the present study showed that the GFR was significantly reduced in the infected group. Both V1 and V2 were also slightly but not significantly decreased which resulted in the lower ECV in monkeys infected with P. knowlesi. As the GFR was reduced much more than ECV, therefore the mean transit time of 51Cr-EDTA in the infected group was longer than that of the normal group. All other intercompartment clearance and fractional transfer rate constants were also found to be lower in the infected group. These findings indicated that there was a delay in the distribution of 51Cr-EDTA between these 2 compartments in monkeys infected with P. knowlesi malaria.

Animals↗
PubMed1989

Possible locations of pH-dependent central chemoreceptors: intramedullary regions with acidic shift of extracellular fluid pH during hypercapnia.

Using liquid membrane pH microelectrodes, we evaluated rapid and transient changes in extracellular fluid (ECF) pH within the medulla during vertebral artery injections of CO2-saturated saline (0.5 ml) in anesthetized (Dial-urethane), spontaneously breathing cats. We found intramedullary regions where ECF pH shifted to the acid side in the time course analogous to respiratory excitation during the CO2 loadings: the acidic shift occurred just before the respiratory excitation. Since most of the tested regions showed no or few changes in ECF pH, the responsive regions are thought to be specific local environments fitting the central chemoreceptors. Forty (85%) out of the 47 responsive regions were found to be scattered in the ventrolateral medulla, i.e. a long narrow zone extending from the ventrolateral surface to the ventral respiratory group (VRG) areas where inspiratory or expiratory activity was frequently recorded. The responsive regions were not necessarily restricted to the superficial ventral layers. We were also able to find the responsive regions in the dorsal area ventral to the nucleus tractus solitarii, though they were fewer in number (7/47). The distributions corresponded rougly to the areas where we had previously identified the tonically firing neurons excited exclusively by stimulation of the central chemoreceptors. These results indicate a possibility that the pH-dependent central chemoreceptors, if any, would be located within the regions demonstrated in this study.

Animals↗
PubMed1971

Effect of extracellular fluid volume expansion on maximum glucose reabsorption rate and glomerular tubular balance in single rat nephrons.

Extracellular fluid volume expansion with isotonic saline (7.5% of body weight) decreased maximum glucose reabsorption rate by rat kidneys at plasma glucose concentrations greater than 30 mM. Glucose reabsorption rate was 30.2 +/-1.6 (SE) mumoles/min.g kidney in nonexpanded rats; it was 18.4 +/-1.5 mumoles/min.g in volume-expanded rats. Glucose reabsorption determined by micropuncture was 92% complete at the end of accessible superficial proximal convolutions. Volume expansion resulted in a slight but statistically insignificant reduction of maximal glucose reabsorption rate in superficial nephrons from 786 +/-35 mumumoles/min.g kidney in nonexpanded rats to 720 +/-30 mumumoles/min.g in volume-expanded rats. Superficial nephron filtration rate was increased by volume expansion from 28.8 +/-1.2 nl/min.g to 36.6 +/-1.5 nl/min.g kidney. In nonexpanded rats, the ratio of glucose reabsorption to glomerular filtration (tmg/sgfr) was similar in superficial and juxtamedullary nephrons. In volume-expanded rats superficial nephron tmg/sgfr was greater than juxtamedullary nephron tmg/sgfr. Juxtamedullary nephron function was measured by puncturing loops of Henle in the exposed papillae of small rats. Volume expansion increased sgfr without much effect on tmg in superficial nephrons while it decreased tmg without much effect on sgfr in deep nephrons. Physical changes produced by volume expansion seem to exert their greatest effect on proximal tubular function in the inner cortex. The increase in heterogeneity of glomerular-tubular balance could account for increased splay of glucose titration curves previously reported to accompany volume expansion.

Absorption↗
PubMed2000

Body composition and resting energy expenditure in humans: role of fat, fat-free mass and extracellular fluid.

OBJECTIVE: The objective of this study was to determine whether there are independent effects of extracellular fluid volume (ECF) and fat mass (FM) on resting energy expenditure (REE) relative to fat-free mass (FFM) in adult men and women. METHODS: Multiple linear regression analysis was used to relate REE, as determined by indirect calorimetry, to FFM and FM (measured using dual energy X-ray absorptiometry) and ECF (measured using bromide space and/or the radiosulfate washout space) in 153 women and 100 men with varying amounts of body fat. RESULTS: REE correlated significantly with FFM and FM in women (r=0.65 and r=0.63, both P<0.001) and men (r=0.62 and r=0.48, both P<0.001, FFM and FM, respectively). In a multiple linear regression analysis FFM, FM and age significantly contributed to the ability to predict REE in both genders. The models that were derived were not significantly different between women and men. In women the contribution to REE from FM was easier to detect when FM was greater. Adjustment of FFM for ECF did not improve the relationship between FFM and REE. CONCLUSIONS: FFM, FM and age are significant, independent predictors of REE in both men and women. Adjustment of FFM for ECF does not improve the ability of FFM to predict REE, which suggests that ECF is a highly integrated component of FFM in healthy adults. Expressing REE relative to FFM alone will introduce errors when lean and obese populations are compared.

Absorptiometry, Photon↗
PubMed1983

Cerebral cortical extracellular fluid H+ and K+ activities during hypotension in cats.

Cerebral cortical blood flow, electrical activity, and extracellular fluid (ECF) pH and K+ ion activities were measured in anesthetized cats (0.7% halothane 65% N2O in O2) subjected to hypotension (mean BP 30-32 and 26-28 mmHg), induced by either practolol and trimetaphan (TMP) or practolol and nitroprusside (NTP). Limited blood withdrawal was also necessary to achieve these blood pressure (BP) levels. Cerebral cortical blood flow during hypotension was greater with NTP than with TMP, and hyperemia occurred in the recovery phase after NTP but not TMP. Electrical activity also was maintained better with NTP. ECF K+ increased in five of six TMP experiments but in only one of six NTP experiments. Values of K+ greater than 15 mM were only seen in the TMP group. Release of K+ into the ECF space occurred at values of cerebral cortical oxygen delivery below 3 ml 100 g-1 min-1. ECF K+ partially recovered after the end of hypotension in all except the experiment with the highest value. A progressive and severe cerebral acidosis was seen in all experiments during induced hypotension, and values below pH 6.50 were present at the stage of K+ increase in the ECF space. It is concluded that the ability of cell membranes in the cat's cortex to maintain normal ionic gradients is depressed by hypotension to these levels with TMP, but not with NTP, and that this difference is related to better-maintained oxygen supply values during NTP hypotension.

Animals↗
PubMed1994

Quantitation of choline in the extracellular fluid of brain tissue with amperometric microsensors.

Amperometric microsensors for the detection of choline in the extracellular fluid of brain tissue have been prepared by immobilizing horseradish peroxidase and choline oxidase onto carbon fiber microcylinder electrodes with a cross-linkable redox polymer. The microcylinders have diameters of 7 or 10 microns and lengths of 200-400 microns. To detect choline, the microsensors are operated at an applied potential of -0.1 V vs SCE. At this potential, ascorbate and other easily oxidizable interferant molecules present in brain tissue are not detected by the electrode. Ascorbate, however, can interfere with the response to choline by acting as a reducing agent in the enzyme-containing polymer film. So, a Nafion overlayer is required in order to reliably detect choline in the presence of physiologically relevant concentrations of ascorbate (approximately 200 microM). The Nafion-coated microsensors have a detection limit of approximately 5 microM choline and give a linear response beyond 100 microM when calibrated in vitro at 37 degrees C. Exposure of the microsensors to brain tissue for several hours causes less than a 10% loss in redox polymer surface coverage and less than a 25% loss in sensitivity to choline. To assess the ability of the microsensors to monitor choline levels in brain tissue, small volumes of a choline solution were injected into brain tissue at a site about 1 mm away from a microsensor. The current arising at the microsensor was converted to choline concentration by calibrating the sensor following the in vivo experiment. The resultant choline concentrations were in excellent agreement with those predicted by appropriate diffusion equations.

Animals↗
PubMed1988

Phosphocreatine, an intracellular high-energy compound, is found in the extracellular fluid of the seminal vesicles in mice and rats.

High levels of phosphocreatine, a compound known to serve as an intracellular energy reserve, were found in the fluid contained in seminal vesicle glands. The concentrations of phosphocreatine in the extracellular fluid in the mouse and rat were found to be 5.6 +/- 1.6 and 2.2 +/- 0.8 mumol/g, respectively, which are higher than the intracellular levels reported for smooth muscles. The creatine concentrations in the seminal vesicular fluid from these two species were 22.8 +/- 3.1 and 13.0 +/- 5.3 mumol/g, respectively. These creatine levels are approximately 100 and 65 times higher than the creatine levels in mammalian blood. Smaller amounts of ATP (phosphocreatine/ATP ratio of 20-40) and traces of ADP were also found. Comparison of the pattern of distribution of macromolecules (proteins and DNA) with the distribution of phosphocreatine between the cells and the fluid of the seminal vesicle indicates that cell lysis did not account for the phosphocreatine in the seminal vesicle fluid. Rather, the available evidence strongly suggests that this high-energy compound is actively secreted. We found that in the testes, the sperm are exposed to the highest known creatine concentration in any mammalian tissue studied. Based on these results and other recent reports, we propose that the extracellular phosphocreatine, ATP, and creatine are involved in sperm metabolism.

Acid Phosphatase↗
PubMed1986

Changes in blood pressure and extracellular fluid with taurine in DOCA-salt rats.

The effect of taurine, a sulfur amino acid, on blood pressure and extracellular fluid volume in deoxycorticosterone acetate (DOCA)-salt hypertensive rats was studied. Uninephrectomized rats showed average systolic pressure of 175 +/- 3 mmHg after the 28 days of treatment with DOCA while receiving 1% NaCl solution to drink. The supplementation of 1 and 3% taurine could prevent the development of DOCA-salt hypertension in a dose-related fashion: average pressures on day 28 after these dosages were 126 +/- 2 and 104 +/- 2 mmHg, respectively. Exchangeable body sodium (sodium "space") at week 4 was significantly increased in DOCA-salt rats compared with that of the vehicle-injected control rats. Furthermore, the taurine supplement increased sodium space significantly in the DOCA-salt rats. Overall, there was a negative correlation between the systolic blood pressure and sodium space at week 4 in the taurine-supplemented DOCA-salt rats (r = -0.492, P less than 0.02), although there was a positive correlation between systolic pressure and sodium space in the DOCA-salt rats and the vehicle-injected control rats (r = 0.036, P less than 0.001). The results suggest that taurine loading may attenuate the rise in blood pressure associated with fluid retention during the DOCA-salt treatment and that the fall in blood pressure with its consequence for the renal circulation may be the cause of fluid retention.

Animals↗
PubMed1979

An explanation of impaired solute mixing in extracellular fluid after hemorrhagic hypotension.

A theory is presented suggesting that the slowed rate of solute dispersion in the extracellular fluid (ECF) space during or after hemorrhagic shock is largely due to a depressed cardiac output, and that mixing may be improved by any fluid therapy that decreases the mean recirculation time for the solute. This theory was tested by comparing solute mixing rates after treatment of shocked anesthetized dogs with either protein-free Ringer solution with Ringer solution containing 5% albumin. The rate of mixing was determined by computer analysis of the disappearance of an ECF tracer from plasma. Compared with Ringer-treated dogs, the albumin-treated group had a faster rate of tracer equilibration, larger cardiac plasma output, and smaller, approximately normal ECF volume. It was concluded that the abnormal dispersion of solute within the ECF space seen during or after hypotension can be corrected simply by restoring the cardiac output, and that albumin-containing fluid may be more effective in this regard than crystalloid solution alone.

Animals↗
PubMed1988

The determination of extracellular fluid volume in whole dental plaque using potassium- or chloride-selective micro-electrodes.

This paper describes a procedure for the determination of the volume of water available for diffusion in whole plaque samples collected from single sites. In this procedure, known micro volumes of H2O were added to single-site plaque samples with calibrated nanoliter pipettes and the potassium or chloride concentration at each dilution measured with ion-selective micro-electrodes. By plotting the inverse of the concentration versus the volume of H2O added, one can determine the original volume of plaque fluid available for diffusion. Volumes determined in simultaneous measurements performed with chloride and potassium micro-electrodes were statistically indistinguishable. From the observed constancy in the initial potassium concentration in rat and human plaque fluid, a simplified macro method is suggested which allows for estimation of the extracellular fluid volume within 20% error in plaque samples.

Animals↗
PubMed1983

Effect of lantana on the composition of the extracellular fluid of sheep.

Experiments were done to examine the effects of lantana poisoning on the composition of the extracellular fluid of sheep. Packed cell volume and total plasma protein increased after dosing with lantana and plasma osmolality increased markedly in the days prior to death. During the early stages of the disease plasma electrolytes were unchanged except for a decrease in potassium, but electrolyte levels varied late in the disease. A metabolic acidosis gradually developed as the disease progressed. It is concluded that fluid, electrolyte and acid-base imbalances are minor in the early stages of intoxication, but in the terminal stages of the disease, some major changes occur.

Ammonia↗