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At least 127 records · Page 7Linked to original sources
PubMed2003

[Assessment of extracellular fluid in cardiac surgery using cardiopulmonary bypass].

Extracellular fluid (ECF) was assessed before and after the cardiac surgery using cardiopulmonary bypass (CPB), by means of a bioimpedance spectrum analyzer to see volumes of the fluid based on changes of the impedance to various frequencies. Difference between the levels before and after the operation was divided by body weight to study about a % BW. Simultaneously its relation to the lung compliance [tidal volume/(peak inspiratory pressure-end expiratory pressure)] was studied. Mean age of the 18 patients was 59.1 +/- 19 years old. ECF was assessed before to 24 hours after the operation continuously and once more after 48 hours. Mean CPB time was 165 +/- 52 minutes, and aortic cross clamp time was 121 +/- 4 minutes. A remarkable increase of ECF was noted immediately after the operation, which further increased gradually till arriving at the peak 4 hours after the operation (4.52 +/- 1.8% BW). Then it gradually decreased to 0.641 +/- 2.7% BW 48 hours later. Lung compliance measured at the same time showed the lowest level 6 hours after the operation. It was known that the bioimpedance spectrum analysis is a simple and non-invasive method, which enables to monitor the vital stable before and after the operation.

Adult↗
PubMed1983

Effects of extracellular fluid volume and plasma bicarbonate concentration on proximal acidification in the rat.

The effects of systemic bicarbonate concentration and extracellular fluid volume status on proximal tubular bicarbonate absorption, independent of changes in luminal composition and flow rate, were examined with in vivo luminal microperfusion of rat superficial proximal convoluted tubules. Net bicarbonate absorption and bicarbonate permeability were measured using microcalorimetry. From these data, net bicarbonate absorption was divided into two parallel components: proton secretion and passive bicarbonate diffusion. The rate of net bicarbonate absorption was similar in hydropenic and volume-expanded rats when tubules were perfused with 24 mM bicarbonate, but was inhibited in volume-expanded rats when tubules were perfused with 5 mM bicarbonate. Volume expansion caused a 50% increase in bicarbonate permeability, which totally accounted for the above inhibition. The rate of proton secretion was unaffected by volume expansion in both studies. The rate of net bicarbonate absorption was markedly inhibited in alkalotic expansion as compared with isohydric expansion. Bicarbonate permeabilities were not different in these two conditions, and the calculated rates of proton secretion were decreased by greater than 50% in alkalosis. Net bicarbonate absorption was stimulated in acidotic rats compared to hydropenic rats. This stimulation was attributable to a 25% increase in the rate of proton secretion. We conclude that (a) proton secretion is stimulated in acidosis, inhibited in alkalosis, and is not altered by volume status; (b) bicarbonate permeability is increased by volume expansion but is not altered by increases in plasma bicarbonate concentration; (c) when luminal bicarbonate concentrations are similar to those of plasma, net bicarbonate absorption is dominated by proton secretion and is thus sensitive to peritubular bicarbonate concentrations, and insensitive to extracellular fluid volume; (d) when luminal bicarbonate concentrations are low and proton secretion is slowed, bicarbonate permeability and thus extracellular fluid volume have a greater influence on net bicarbonate absorption.

Absorption↗
PubMed2003

A comparison of central brain (cerebrospinal and extracellular fluids) and peripheral blood kinetics of phenytoin after intravenous phenytoin and fosphenytoin.

Phenytoin (PHT) is a first-line drug in the treatment of status epilepticus. However, the parenteral PHT formulation is associated with administration difficulties and therefore fosphenytoin (FosPHT), a PHT pro-drug, has been developed. As the peripheral (blood) and central (cerebrospinal fluid [CSF] and brain extracellular fluid [ECF]) kinetic inter-relationship of PHT after i.v. FosPHT administration is unknown we sought to ascertain the relationship and to compare it to that of i.v. PHT. A freely behaving rat model, which allows for the concurrent and temporal sampling of blood (jugular vein), CSF (cisterna magna) and brain ECF (frontal cortex and hippocampus), was used. PHT and FosPHT were administered by i.v. infusion and blood, CSF and microdialysate samples collected at timed intervals up to 6 hours. The pharmacokinetic parameters in plasma of PHT after PHT and FosPHT (30 and 60 mg/kg) administration were indistinguishable. The PHT plasma free fraction (free/total concentration ratio) was 0.25-0.31 and 0.26-0.31 for PHT and FosPHT, respectively. Mean PHT Tmax values for CSF were 9-13 minutes. The equivalent values in the frontal cortex and hippocampal ECF were 29-34 minutes. Cmax values increased dose-dependently and were independent of whether PHT or FosPHT was administered. Furthermore the kinetic profiles of PHT for the frontal cortex and hippocampus were indistinguishable suggesting that PHT distribution in the brain is not brain region specific. Thus, overall, the central and peripheral kinetics of PHT are indistinguishable after PHT and FosPHT.

Animals↗
PubMed2001

The cerebral hemorrhage-producing cystatin C variant (L68Q) in extracellular fluids.

A variant of the normal extracellular cysteine protease inhibitor cystatin C (L68Q-cystatin C), is the amyloid precursor in hereditary cystatin C amyloid angiopathy (HCCAA). It has been suggested that the mutation causes cellular entrapment of L68Q-cystatin C in vivo and that the variant protein is not secreted to extracellular fluids. In order to test this hypothesis, we used matrix-assisted laser desorption ionization time-of-flight mass spectrometry in an effort to demonstrate the presence of L68Q- along with wildtype cystatin C in plasma and cerebrospinal fluid (CSF) of HCCAA-patients. Plasma from all five investigated HCCAA-patients contained both L68Q- and wildtype cystatin C. The presence of approximately equal amounts of cystatin C dimers and monomers was demonstrated in plasma from HCCAA-patients, whereas only monomers could be found in normal plasma. L68Q-wildtype-cystatin C heterodimers seem to be present in the dimeric cystatin C population. CSF from six HCCAA-patients also contained cystatin C-dimers and monomers, but the dimeric fraction was minute. CSF from control patients did not contain dimeric cystatin C. These results suggest that the milieu of L68Q-cystatin C is important for its stability and dimerization status and that certain milieus might hinder its further development into oligomers, amyloid fibrils and other precipitating aggregates.

Adult↗
PubMed1992

Fluorometric quantitation of adenosine concentration in small samples of extracellular fluid.

Adenosine is a naturally occurring nucleoside which regulates many physiological processes by interacting with adenosine-specific receptors. Knowledge of the extracellular adenosine concentration at the site of adenosine receptors on target cells is required for an understanding of mechanisms involving the action of the nucleoside. Samples of extracellular fluid which reside in close proximity to the surface of target cells are frequently small in volume. This report describes improvements in accuracy and reliability of a fluorometric assay designed for determining the concentration of adenosine in microliter samples of extracellular fluids. The utility of the assay is demonstrated by determining adenosine concentrations in interstitial and coronary effluent samples from normoxic perfused rat hearts. The assay also clearly detects changes in the interstitial and coronary effluent adenosine levels produced by isoproterenol stimulation or hypoxia. Thus, this assay is useful for determining the adenosine concentration in microliter samples of extracellular fluid and should facilitate investigations dealing with the functions of adenosine.

Acetaldehyde↗
PubMed1989

Digitalislike immunoreactive substances and extracellular fluid volume status in chronic hemodialysis patients.

Circulating digitalislike immunoreactive substances (DLIS) may represent a class of volume-sensitive natriuretic factors. Chronic renal failure patients are known to have elevated levels of circulating natriuretic activity and also to have detectable DLIS. Using digoxin radioimmunoassay, DLIS levels were measured in desalted, deproteinized plasma from 15 stable hemodialysis patients. Predialysis DLIS was 109.3 +/- 6.3 pg/mL (digoxin equivalents) and decreased to 97.5 +/- 5.9 pg/mL following dialysis (P less than 0.001). Predialysis DLIS correlated with weight gain from the prior dialysis (P less than 0.01). The degree of extracellular fluid volume expansion predialysis also correlated with predialysis DLIS (P less than 0.01). Postdialysis DLIS also correlated with postdialysis extracellular fluid volume status (P less than 0.01). DLIS levels in dialysis patients were higher than in 50 normal subjects (30.0 +/- 1.2 pg/mL; P less than 0.001). Also, the changes in DLIS with dialysis were paralleled by similar changes in simultaneously measured human alpha-atrial natriuretic peptide (ANP) levels. These results demonstrate that (1) DLIS levels are higher in hemodialysis patients than in normal individuals; (2) with dialysis, DLIS levels increase and decrease in association with extracellular fluid volume expansion and removal, respectively; (3) DLIS levels correlate with the degree of extracellular fluid volume expansion in dialysis patients; and (4) DLIS levels change in parallel with levels of another class of natriuretic factor ANP. These characteristics are consistent with the hypothesis that DLIS represents a volume-sensitive factor.

Adult↗
PubMed2003

Effects of estrogen and progesterone administration on extracellular fluid.

To determine the effect of estrogen and progesterone on plasma volume (PV) and extracellular fluid volume (ECFV), we suppressed endogenous estrogen and progesterone by using the gonadotropin-releasing hormone (GnRH) antagonist ganirelix acetate in seven healthy women (22 +/- 1 yr). Subjects were administered GnRH antagonist for 16 days. Beginning on day 5 of GnRH antagonist administration, subjects were administered estrogen (E(2)) for 11 days, and beginning on day 12 of GnRH antagonist administration, subjects added progesterone (E(2)-P(4)) for 4 days. On days 2, 9, and 16 of GnRH antagonist administration, we estimated ECFV (inulin washout), transcapillary escape rate of albumin (TER(alb)), and PV (Evans blue dye). Plasma E(2) concentration increased from 17.9 +/- 4.5 (GnRH antagonist) to 195.9 +/- 60.1 (E(2), P < 0.05) to 245.6 +/- 62.9 pg/ml (E(2)-P(4), P < 0.05). Compared with GnRH antagonist (1.3 +/- 0.5 ng/ml), plasma P(4) concentration was unchanged during E(2) (0.9 +/- 0.3 ng/ml) and increased to 9.4 +/- 3.1 ng/ml during E(2)-P(4) (P < 0.05). Both E(2) (44.1 +/- 3.1 ml/kg) and E(2)-P(4) (47.7 +/- 2.8 ml/kg) increased PV compared with GnRH antagonist (42.8 +/- 1.3 ml/kg, P < 0.05). Within-subjects TER(alb) was a strong negative predictor of PV (mean r = 0.92 +/- 0.03, P < 0.05), and TER(alb) was lowest during E(2)-P(4) (5.7 +/- 0.5, 4.1.0 +/- 1.1, and 2.8 +/- 0.9%/h, P < 0.05, for GnRH antagonist, E(2), and E(2)-P(4), respectively). ECFV was reduced during E(2) (227 +/- 31 ml/kg, P < 0.05) compared with both GnRH antagonist (291 +/- 37 ml/kg) and E(2)-P(4) (283 +/- 19 ml/kg). Thus the percentage of extracellular fluid in the plasma compartment increased to 21.0% (P < 0.05) during E(2) compared with GnRH antagonist (16.1%) and E(2)-P(4) (17.2%) administration. Thus E(2) increased PV via actions on the capillary endothelium to lower TER(alb) and favor intravascular water retention, whereas during E(2)-P(4) PV increased via the combined responses of ECFV expansion and lower TER(alb).

Adult↗
PubMed1975

Effects of aspirin on renal sodium excretion, blood pressure, and plasma and extracellular fluid volume in salt-loaded rats.

The effect of aspirin administration and presumed blockade of prostaglandin synthesis on renal sodium excretion, plasma and extracellular fluid volumes, and blood pressure were examined in rats on a high sodium intake. After acute salt loading aspirin treated rats showed an impaired sodium excretion, while no changes in glomerular filtration rate were observed. In chronically loaded rats (7 weeks) administration of aspirin induced significant increases in both plasma and extracellular fluid volume, but no significant changes in blood pressures were found. The results are consistent with the hypothesis that prostaglandins mediate renal sodium excretion and therefore participate in extracellular fluid volume regulation.

Animals↗
PubMed1985

Mannitol penetration of liver cells in estimations of extracellular fluid volume.

It has been suggested that since mannitol is excreted in the bile it may enter the liver cell and hence over-estimate extracellular fluid volume if used as a marker. Boluses of D-[14C]mannitol were injected into anaesthetized, nephrectomized dogs. After equilibration, liver biopsy samples were taken. Total liver water was estimated gravimetrically and compared with extracellular fluid volume estimated from the biopsy samples using beta-counting. There was no significant difference between these two estimations. However D-[14C]mannitol and [14C]inulin carboxylic acid spaces for liver were significantly different. This suggests that mannitol penetrates liver cells. A correction factor is derived to enable the technique to be used more accurately in 'whole-body' extracellular fluid volume estimation.

Animals↗
PubMed1978

Plasma volume and extracellular fluid volume in horses at rest and following exercise.

Plasma volume and extracellular fluid volume were determined in horses at rest and immediately after a standardized exercise test. Exercising during training demonstrated no detectable effect on plasma or extracellular fluid volume determinations when compared with resting values. An explanation of this finding and an argument for the proper analysis of plasma and extravascular fluid volumes are presented.

Animals↗
PubMed1992

Drainage of brain extracellular fluid into blood and deep cervical lymph and its immunological significance.

Cerebral extracellular fluids drain from brain to blood across the arachnoid villi and to lymph along certain cranial nerves (primarily olfactory) and spinal nerve root ganglia. Quantification of the connection to lymph in rabbit, cat and sheep, using radiolabelled albumin as a marker of flow, indicates that a minimum of 14 to 47% of protein injected into different regions of brain or cerebrospinal fluid passes through lymph. The magnitude of the outflow to lymph is at variance with the general assumption that the absence of conventional lymphatics from the brain interrupts the afferent arm of the immune response to brain antigens. The immune response to antigens (albumin or myelin basic protein) introduced into the central nervous system (CNS) has been analysed using a rat model with normal brain barrier permeability. The micro-injection of antigen into brain or cerebrospinal fluid elicits a humoral immune response, with antibody production in cervical lymph nodes and spleen, and also affects cell-mediated immunity. Furthermore, antigen may be more immunogenic when administered into the CNS than into conventional extracerebral sites. Clearly, the afferent arm of the immune response to antigens, within the CNS, is intact. Modern studies suggest that the efferent arm is also intact with passage of activated lymphocytes into the brain. Results support a new view of CNS immunology which incorporates continuous and highly regulated communication between the brain and the immune system in both health and disease.

Animals↗
PubMed1984

Monitoring the stimulated release of dopamine with in vivo voltammetry. II: Clearance of released dopamine from extracellular fluid.

Microvoltammetric electrodes implanted in the caudate nucleus of the anesthetized rat have been used to monitor dopamine released following electrical stimulation of the medial forebrain bundle. These electrodes are fabricated from unmodified carbon fibers and have been used with normal pulse voltammetry. Dopamine appears in the vicinity of the electrode when the stimulation is initiated, and disappears almost immediately when the stimulation is terminated. The data suggest that the effective diffusion distance is less than 100 micron. Postmortem analysis using liquid chromatography with electrochemical detection shows that dopamine released in this manner is metabolized to 3,4-dihydroxyphenylacetic acid (DOPAC); however, neither substance is observed electrochemically in the extracellular fluid within seconds after the stimulation. In addition, inhibitors of neuronal uptake of dopamine, amphetamine (1.8 or 15 mg X kg-1) or benztropine (25 mg X kg-1), or of dopamine metabolism, pargyline (150 mg X kg-1) or tropolone (100 mg X kg-1), do not significantly affect the rate at which dopamine disappears from extracellular fluid, although they can affect the amount released. These results suggest that dopamine cannot freely diffuse in the extracellular fluid because an extraneuronal uptake mechanism exists that clears dopamine from extracellular fluid into an extraneuronal pool where metabolism to 3,4-dihydroxyphenylacetic acid occurs. Dopamine can be observed during electrical stimulation of the ascending fibers because neuronal and extraneuronal uptake systems are unable to remove dopamine on these short time scales.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1980

Effects of dehydration on plasma water and extracellular fluid volumes in the rat.

Dehydration was induced in rats by depositing 3 ml of hyperosmolar glucose (1670 mOsm/kg) in a closed small bowel loop. The plasma water and extracellular fluid volumes of the whole animal and selected tissues were subsequently studied with 125I human serum albumin and 51Cr EDTA. The fluid accumulation in the bowel was equivalent to 122% of the plasma water volume. The plasma water volume of the whole animal was significantly reduced by 31%, while the extracellular fluid volume reduction by 8% was not statistically significant. The regional extracellular fluid volumes decreased in the lung (9%), the liver (34%), the gastric antrum (15%) and the omental fat (24%). The results show regional differences in tissue response to dehydration.

Animals↗