SEARCH · PubMed Health

Results for “EXTRACELLULAR FLUID”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59Linked to original sources

PubMed1970

Distribution of ions and electrical potential differences between mother and foetus at different gestational ages in goats and sheep.

1. Potential differences associated with the compartments of goat and sheep conceptuses have been measured in vivo and in vitro during the last half of gestation and the osmolarity, and the [Na(+)], [K(+)], and [Cl(-)] of maternal and foetal plasma and amniotic and allantoic fluid taken from these animals were determined.2. The potential difference (p.d.) patterns of both goats and sheep were the same.(a) The transplacental p.d. was about 71 mV (foetus negative) in the goat, and about 51 mV (foetus negative) in the sheep.(b) The amniotic fluid p.d. (i.e. the p.d. measured between the maternal extracellular fluid and the amniotic fluid) decreased as gestation advanced (from 110 to 70 mV in the goat, and 90 to 50 mV in the sheep) and was equal to the sum of the transplacental p.d. and a p.d. between the foetal blood and the amniotic fluid. The amniotic fluid was negative relative to both maternal and foetal blood.(c) An allantoic fluid p.d. (measured between the maternal extracellular fluid and the allantoic fluid) of about 107 mV in the goat, and about 96 mV in the sheep, was equal to the sum of the transplacental p.d. and a p.d. between the foetal blood and the allantoic fluid. The allantoic fluid was negative relative to both maternal and foetal blood.(d) The results suggest that p.d.s of the fluid sacs arise from activity between the foetal fluids and the blood perfusing the foetal membranes, and not from activity across the full thickness of the foetal membranes.3. The ionic concentrations were considered in relation to the electrochemical gradients found between the maternal and foetal fluid compartments to determine whether the ions were distributed according to electrochemical equilibrium.(a) It seems that ions in the amniotic fluid tend to equilibrate with foetal plasma, and not with maternal plasma or allantoic fluid, that changes in the [Na(+)] and [K(+)] of amniotic fluid can be accounted for largely in terms of passive factors, and that variations in the [Cl(-)] are associated with activity of an electrogenic Cl(-) pump directed from the foetal blood into the amniotic fluid.(b) It appears that ions in the allantoic fluid can exchange with those of both maternal and foetal plasma, that an electrogenic pump effects absorption of Na(+) from the allantoic fluid into the foetal blood, and that the [K(+)] and [Cl(-)] of allantoic fluid are maintained largely by passive exchange under the action of electrochemical gradients between maternal plasma and allantoic fluid, and between foetal plasma and allantoic fluid.4. The results considered in the context of Na(+) passage between mother and foetus call in question the general assumption that all Na(+) reaches the foetus by passing across the placenta.

Amniotic Fluid↗

PubMed1999

Osmolar disorders.

OBJECTIVE: To present a practical approach to the management of osmolar disorders by considering the mechanisms involved in their development. DATA SOURCES: Articles and published peer-review abstracts on the mechanisms and management of disorders of plasma osmolality. SUMMARY OF REVIEW: In health, plasma osmolality is determined largely by the concentration of sodium and its accompanying anion, and regulated by mechanisms that regulate body water. Water excess or deficiency causes hypo and hyper osmolality, respectively. Hyperosmolality may also be caused by an excess of body solutes, with the biochemical and clinical features depending on whether these compounds are impermeant (i.e. remain in the extracellular fluid) or permeant (i.e. are distributed throughout the total body water). Sodium metabolism is regulated by those mechanisms that regulate extracellular fluid volume. An increase (or decrease) in total body sodium is associated with retention (or excretion) of body water, an increase (or decrease) in the extracellular fluid (ECF) volume, and no change in plasma osmolality. The initial presentation of an osmolar disorder is usually with an abnormal plasma sodium, therefore management often focuses on treatment of hypo or hypernatraemia. However, treatment requires an estimation of all fluid and solute excesses and deficiencies, with the need or otherWise for prompt correction depending upon the nature of the disorder and time taken for it to develop. CONCLUSIONS: Osmolar disorders are associated with varying changes in total body fluid and solute. Consideration of these changes, using a body fluid compartment model, is useful in understanding the abnormalities present and to facilitate management.

Journal Article↗

PubMedDate not supplied

Role of retinal detachment subretinal fluid on extracellular matrix metabolism.

PURPOSE: To examine the in vitro effects of subretinal fluid (SRF) from patients with retinal detachment on extracellular matrix turnover. METHODS: Matrix metalloproteinase (MMP) activity was explored by radiolabeled substrate degradation and zymography. Human lung fibroblasts were used to analyze SRF effects on collagen synthesis and cell proliferation. Transforming growth factor-beta(2) (TGF-beta(2)) concentration was determined in SRF samples by a quantitative sandwich enzyme immunoassay. RESULTS: MMP-2 and MMP-9 gelatinolytic activity was observed in all SRF samples. Collagenase activity was not detected in SRF from patients with holes and recurrent retinal detachment. All SRF samples stimulated fibroblast proliferation and collagen synthesis but SRF samples from recurrent retinal detachment patients with previous retinal tears had the largest effect with the largest TGF-beta(2) concentration. CONCLUSIONS: The gelatinolytic activity found in all SRF samples might be associated with the retinal detachment process. Low collagenase activity with an increase in collagen synthesis could indicate a risk factor to the development of proliferative vitreoretinopathy.

Adolescent↗

PubMed1998

Extracellular glutamate increases in rostral ventrolateral medulla during static muscle contraction.

The ventrolateral medulla is an important site involved in increases in arterial pressure and heart rate during static muscle contraction. Glutamate, an excitatory amino acid neurotransmitter, appears to play a role in mediating these responses. We measured glutamate concentration in the extracellular fluid of the rostral ventrolateral medulla during static muscle contraction in anesthetized rats. A 2-min tibial nerve stimulation-evoked muscle contraction increased blood pressure by 30 +/- 4 mmHg and heart rate by 32 +/- 4 bpm. Extracellular glutamate in the rostral ventrolateral medulla also increased from 9 +/- 1 pmol/4 microl to 14 +/- 1 pmol/4 microl. Results were repeatable over two subsequent contractions. Tibial nerve stimulation following neuromuscular blockade did not elicit changes in blood pressure, heart rate or extracellular fluid glutamate. Data demonstrate that muscle contraction increases extracellular fluid concentration of glutamate in the rostral ventrolateral medulla, suggesting that rostral ventrolateral medullary glutamate release is a neurochemical change associated with cardiovascular responses during static muscle contraction.

Animals↗

PubMed2003

Hints of western medicine from Chinese medicine.

As a biochemist, I have been studying lipolytic and lipogenic pathways in fat cells since 1963. In 1966, I proposed a hormone-sensitive substrate theory in which catecholamines might not act on lipase but on substrate during their lipolytic processes. The lipolytic and lipogenic pathways are negative and positive processes in triglyceride content of fat cells. Insulin inhibits the negative process (lipolysis) and stimulates the positive process (lipogenesis from glucose). On the other hand, catecholamine stimulates the negative process and inhibits the positive one. These hormones discriminate the negative and positive rules and regulate opposite ways. We tried to find these hormone-like substances in various natural products. We isolated tea saponins, chitosan, and others as insulin-like substances and dimethyl-xanthine as a catecholamine-like one. It is well known that extracellular fluid pH changes from 7.4 to 6.8. Reduction of the pH from 7.4 causes insulin resistance. Insulin failed to stimulate glucose uptake at pH 7.0 of the extracellular fluid. We found minus ions, which stimulated lipogenesis from glucose by raising extracellular fluid pH to 7.4. These are our approaches to find functional substances that prevent lifestyle-related diseases.

Adenosine↗

PubMed2002

Effect of saline acclimation on body water and sodium compartmentalization in Pekin ducks (Anas platyrhynchos).

The compartmentalization of body fluids was measured in individual Pekin ducks ( Anas platyrhynchos) drinking freshwater and after sequential acclimation to 300 mM NaCl and 400 mM NaCl. Total body water, extracellular fluid volume, plasma volume and exchangeable sodium pool were measured using (3)H(2)O, [(14)C]-polyethylene glycol, Evans Blue dye, and (22)Na dilution, respectively. Following acclimation to 300 mM NaCl, body mass decreased, but total body water and total exchangeable sodium pool were unaltered. Na and water were redistributed from the extracellular fluid (interstitial fluid) compartment into the intracellular fluid compartment. Following further acclimation to 400 mM NaCl, body mass, total body water and intracellular fluid volume decreased, but exchangeable sodium pool and extracellular fluid volume were unchanged. Our results suggested that, when Pekin ducks drink high but tolerable salinities, they maintain total body water, but redistribute Na(+) and water from interstitial fluid to the intracellular fluid compartment. When stressed beyond their ability to maintain total body water, they lose water from the intracellular fluid.

Acclimatization↗

PubMed2002

Pericardial effusion in the nephrotic syndrome.

Hydropericardium is a known cause of pericardial effusion related to severely expanded extracellular fluid volume. Nephrotic patients have expanded extracellular fluid volume but obviously may have other causes for pericardial effusion. We tested the hypothesis that pericardial effusion is related to inflammation and not to hydropericardium in patients with nephrotic syndrome. Twenty nephrotic patients with systemic lupus erythematosus (SLE) were compared to 20 patients with nephrotic syndrome of other causes. No patient in either group had symptoms or signs of pericardial disease. Pleural effusion and ascites were equally common in SLE-nephrotic patients compared to non-SLE-nephrotic patients. However, 8 SLE patients had pericardial effusion, while none of the non-SLE-nephrotic patients had pericardial effusion. We suggest that hydropericardium is rare in nephrotic patients and that an inflammatory or other secondary cause should be considered when pericardial effusion complicates nephrotic syndrome.

Adult↗

PubMed2004

Calcium ions are abnormally distributed in the skin of haemodialysis patients with uraemic pruritus.

BACKGROUND: Although a close relationship between uraemic pruritus and serum calcium levels has been demonstrated for some time, the degree of pruritus was not always correlated with calcium concentrations. In the present study, we assessed calcium ion distribution in the skin of chronic haemodialysis patients with and without pruritus. METHODS: We excluded patients with concomitant psoriasis or atopic dermatitis or with a previous history of allergy, those who had an arteriovenous fistula created prior to induction of haemodialysis, and patients with only mild pruritus. From the enrolled 22 haemodialysis patients, we obtained forearm skin samples during arteriovenous fistula surgery. These patients were divided into two groups based their grade of pruritus. The pruritus group included patients with moderate to severe grades of pruritus (n = 11, age 64 +/-13 years) and the non-pruritus group consisted of patients without pruritus (n = 11, age 59 +/-13 years). We compared the distribution of calcium ions in the epidermis between the two groups using the ion-capture method (oxalate-pyroantimonate-osmium technique). In addition, we examined and compared the groups for thicknesses of the basal, spinous and granular layers, as well as of the stratum corneum using an electron microscope. RESULTS: The pruritus group had significantly higher calcium ion deposition in the extracellular fluid and cytoplasm of basal cells, and in the extracellular fluid, nuclei and cytoplasm of spinous cells compared with the non-pruritus group. In contrast, calcium ion depositions were similar between the two groups in the dermis/basal layer interface, the nucleus of basal cells, the nucleus and cytoplasm of granular cells, exterior of granular cells, the granular cells/stratum corneum interface, and in the interior and exterior of corneocytes. Although the stratum corneum was significantly thicker in the pruritus group than in the non-pruritus group, there were no differences in basal cell, spinal cell or granular cell layer thicknesses. CONCLUSION: In chronic haemodialysis patients with pruritus, the calcium ion concentration in the deepest layer of the epidermis was increased, which indicated a disrupted calcium ion gradient in the skin. These findings point to a role for increased skin calcium ion concentrations in the development and/or maintenance of uraemic pruritus. However, more extensive studies in larger patient cohorts will be necessary to confirm this hypothesis.

Aged↗

PubMed1992

Altered cell volume regulation in ras oncogene expressing NIH fibroblasts.

Expression of the Ha-ras oncogene has been reported to stimulate the dimethylamiloride sensitive Na+/H+ exchanger and Na+,K+,2Cl- cotransport, both transport systems which are involved in cell volume regulation. The present study has been performed to test for an influence of ras oncogene expression on cell volume regulation in NIH 3T3 fibroblasts expressing the Ha-ras oncogene (+ ras). As controls served NIH 3T3 fibroblasts not expressing the ras oncogene (-ras). In isotonic extracellular fluid, the cell volume of + ras cells (2.70 +/- 0.08 pl) is significantly greater than the cell volume of -ras cells (2.04 +/- 0.10 pl). Both, + ras and -ras cells exhibit a regulatory cell volume increase in hypertonic extracellular fluid and a regulatory cell volume decrease in hypotonic extracellular fluid. The regulatory cell volume decrease is inhibited by 1 mmol/l quinidine and barium, the regulatory cell volume increase is inhibited in -ras and +ras cells by dimethyl-amiloride (100 mumol/l) and, only in +ras cells, by furosemide (100 mumol/l) and bumetanide (10 mumol/l). In conclusion, expression of the ras oncogene leads to a shift of the set point for cell volume regulation to greater cell volumes, which may contribute to the activation of the Na+/H+ exchanger and Na+,K+,2Cl- cotransport.

3T3 Cells↗

PubMed1988

Characterization of hippocampal norepinephrine release as measured by microdialysis perfusion: pharmacological and behavioral studies.

The release of endogenous norepinephrine in hippocampus was studied in freely moving rats with microdialysis perfusion. Using a loop-style dialysis probe, the basal amount of norepinephrine collected in 15-min fractions averaged 12 pg/25 microliters. Correcting for recovery (21%), the concentration of norepinephrine in the extracellular fluid of hippocampus under resting conditions was estimated to be approximately 14 nM. The alpha 2 adrenoceptor antagonist yohimbine (5.0 mg/kg, i.p.) increased norepinephrine efflux to 230% of basal levels. Clonidine (0.3 mg/kg, i.p.), an alpha 2 adrenoceptor agonist, decreased norepinephrine efflux to 56% of baseline. Addition of the reuptake blocker desipramine (1.0 microM) to the perfusate had no significant effect on norepinephrine efflux. However, increasing the K+ concentration of the perfusate to 30 mM increased norepinephrine efflux to 196% of baseline, and this effect was increased nearly two-fold by the addition of desipramine to the perfusate (364% of baseline). Restraint stress and intermittent tailshock increased norepinephrine efflux to 213% and 234% of baseline, respectively. The results suggest that microdialysis is a useful way to study norepinephrine release in hippocampus and they permit several conclusions to be drawn. First, the data obtained with systemic administration of alpha 2 adrenoceptor drugs emphasize the fact that a variety of regulatory mechanisms exist that may affect transmitter levels in the extracellular fluid. Second, the ratio of extracellular to intracellular norepinephrine in hippocampal tissue is considerably higher than that reported for dopamine in striatum. Coupled with the small effect of norepinephrine uptake blockade, this suggests that nerve terminal density is an important factor in determining the concentration of catecholamines in the extracellular fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Microdialysis in pharmacokinetics.

Microdialysis is a method by which the extracellular fluid from almost any organ or fluid compartment can be sampled without loss of volume for long periods of time. By this method direct access is gained to previously intractable fluid spaces such as the brain extracellular fluid and the mechanisms of transfer over, for example, the blood brain barrier (BBB) and the blood placenta barrier can be studied with fewer assumptions made than previously. We here concentrate on three aspects of the use of microdialysis in pharmacokinetics. Firstly, some of the practical experimental requirements are reviewed with particular attention paid to the recovery problem. Secondly, the calculation of pharmacokinetic parameter estimates is discussed including an algorithm for dealing with multicompartment models and direct studies of transfer rate constants. Thirdly, the possibility to model and experimentally examine various transport mechanisms is discussed. The theoretical results are applied to data from a study of the anti-HIV drugs zidovudine and alovudine (3'-fluorothymidine) and their distribution across the blood brain barrier in rats.

Algorithms↗

PubMed1996

The benefits and side effects of ramped hypertonic sodium dialysis.

The effectiveness of ramped hypertonic sodium dialysis (RHSD) is controversial because of the prevalence of side effects (weight gain and hypertension). Standard dialysis (SD) was therefore compared with RHSD in a double-blind controlled crossover trial. Eleven patients who suffered from symptoms attributable to water shifts from extracellular fluid to intracellular fluid (headaches or hangover) or extracellular-fluid volume contraction (cramps or lightheadedness) and five asymptomatic patients were enrolled in the study. RHSD was individually tailored to each patient (to minimize thirst) during a 2-wk run-in period. Patients then received RHSD and SD for a period of 3 wk in randomized sequence. Outcome measures were both objective and subjective ratings on questionnaires. Significant differences were found between the two treatments, with RHSD improving specific problems (70% of lightheadedness/cramps, 100% of headaches/hangover) versus SD. Weight gain and hypertension were not different between the two treatments despite increased thirst sensation reported by 14/16.94% of patients preferred RHSD. Long-term studies in 20 different patients demonstrated the lack of increase in blood pressure or weight gain after 3 and 6 months of therapy.

Blood Pressure↗

PubMed2003

Effects of lipopolysaccharides on calcium homeostasis in isolated pancreatic acinar cells of rat.

AIM: To investigate the effects of lipopolysaccharides (LPS, endotoxin) on the calcium content in pancreatic acinar cells and the origin of Ca2+ during calcium overload induced by LPS, further to explore the mechanism of LPS in inducing calcium overload and pancreatic acinar cell injury. METHODS: Male rat pancreatic acinar cells were isolated by collagenase digestion and loaded with Fluo-3/AM, then exposed to varying doses of LPS (from 1 mg/L to 20 mg/L). The dynamic change of [Ca2+]i in single pancreatic acinar cell in the absence and presence of Ca2+ in extracellular fluid was determined by laser scanning confocal microscopy. Cell viability was determined by MTT at different time points after treatment with LPS. RESULTS: Under physiological calcium concentration in extracellular fluid, LPS (10 mg/L) initiated a rapid, concentration-dependent rise in intracellular [Ca2+]i and consequent cell damage (P<0.05). LPS induced a slight rise of [Ca2+]i in the calcium-free extracellular fluid containing egtazic acid 1 mmol/L and addition of extracellular calcium in the presence of LPS resulted in a more immediate and remarkable rise of [Ca2+]i, which reached the peak value within 150 s and maintained the value sustainedly. Egtazic acid attenuated LPS-induced cell damage (P<0.05). The increase in intracellular [Ca2+]i preceded the pathological alteration of pancreatic acinar cells. CONCLUSION: LPS directly induced the injury and the disorder of calcium homeostasis in isolated rat pancreatic acinar cell. Calcium overload is an early event in the pathogenesis of LPS-induced cell damage. Origin of the [Ca2+]i in cytoplasma of pancreatic acinar cells during calcium overload is mainly due to the influx of extracellular Ca2+. Calcium homeostasis disorder may be one of the causes or at least an important mediator of LPS-induced pancreatic acinar cell damage.

Animals↗

PubMed1980

Preservation of extracellular space during fixation of the brain for electron microscopy.

Adult mammalian brain contains about 20% extracellular space, but fixatives cause the cellular processes to ingest the extracellular fluid, and the space is not preserved in electron micrographs prepared by any of the conventional methods. This distortion can be prevented by replacing part of the sodium chloride in the extracellular fluid by an impermeant solute such as sucrose. To do this, the blood-brain barrier can be opened by vascular perfusion at 300 mmHg pressure, or the barrier can be bypassed by immersion of thin slices of fresh brain in the impermeant solution. In either case, addition of aldehyde fixatives and conventional processing then leads to the preservation of extracellular space in electron micrographs. Both procedures are as easy to use for routine fixation as conventional methods. In well fixed tissue the cellular processes are different in size, shape and electron density from the inflated profiles seen after the ingestion of extracellular fluid that accompanies conventional fixation. Moreover, extracellular space is found to separate widely some cellular elements, while leaving others contiguous.

Animals↗

PubMed1997

Microdialysis assessment of fibrin glue containing sodium alginate for local delivery of doxorubicin in tumor-bearing rats.

This study was designed to assess a local drug delivery system of an anticancer agent, doxorubicin (DOX), using fibrin glue (Beriplast P) as a drug carrier. In vitro release of DOX from the fibrin glue was examined by a dialysis method in the presence and absence of sodium alginate. The in vitro mean dissolution times of DOX with solution, fibrin glue, and fibrin glue containing sodium alginate were 3.7 h, 8.7 h, and 81 h, respectively, indicating a sustained release of DOX from fibrin glue, especially in the presence of sodium alginate. Fibrin glue containing 6 mg of DOX and 2.5 mg of sodium alginate was applied on the surface of an AH60C tumor at the back of rats. DOX concentrations in the tumor extracellular fluid were monitored by a microdialysis method. Local application of DOX using fibrin glue containing sodium alginate to the tumor resulted in extremely higher concentrations in the tumor extracellular fluid than those in plasma (AUC ratio > 800), indicating an advantage of the site-specific delivery of DOX using fibrin glue with sodium alginate. The tumor volumes were inversely correlated with tumor extracellular fluid-to-plasma AUC ratios (r = 0.882), suggesting the relevance of tumor size in the drug efflux from tumor to blood. In conclusion, the site-specific delivery of DOX using fibrin glue with sodium alginate to the tumor was demonstrated to be advantageous with regard to the extent and duration of drug concentrations in the tumor extracellular fluid, as assessed by a microdialysis technique.

Alginates↗

PubMedDate not supplied

A new technique for the quantification of peripheral edema with application in both unilateral and bilateral cases.

Current noninvasive techniques for the routine and frequent quantification of peripheral lymphedema in patients are total limb volume measurement (by water immersion or by circumferential measurements) and bioelectrical impedance analysis (BIA). However both of these techniques require standardizing the measurement using a contralateral measurement from the unaffected limb. Hence these techniques are essentially restricted to unilateral lymphedema. This paper describes the results from a preliminary study to investigate an alternative approach to the analysis of the data from multiple frequency BIA to produce an index of lymphedema without the need for normalization to another body segment. Twenty patients receiving surgical treatment for breast cancer were monitored prior to surgery and again after diagnosis with unilateral lymphedema. The data recorded were total limb volume, by circumferential measurements; and BIA measurements of both limbs. From these measurements total limb volumes and extracellular fluid volumes were calculated and expressed as ratios of the affected limb to that of the unaffected limb. An index of the ratio of the extracellular fluid volume to the intracellular fluid volume was determined. This ECW/ICW index was calculated for both the affected and unaffected limbs at both measurement times. Results confirmed that the established techniques of total limb volume and extracellular fluid volume normalized to the unaffected contralateral limb were accurate in the detection of lymphedema (p < 10(-6)). Comparison of the ECW/ICW index from the affected limb after diagnosis with that from the pre-surgery measurement revealed a significant (p < 10(-6)) and considerable (75%) increase. The results of this pilot study suggest that by using multiple frequency bioelectrical impedance analysis, an index of the ECW/ICW ratio can be obtained and this index appears to have an equal, or better, sensitivity than the other techniques in detecting lymphedema. More importantly, this index does not require normalization to another body segment and can be used to detect all types of peripheral edema including both unilateral and bilateral lymphedema.

Adult↗

PubMed1984

Moxalactam penetration into normal heart valve, cardiac vegetations, and myocardium in relation to protein binding and physiological distribution spaces.

Rabbits with catheters implanted in the left ventricle were given a single dose of moxalactam and sacrificed at various times thereafter for measurement of the concentration of this antimicrobial agent in serum, heart muscle, and various heart valves. Penetration into both extravascular sites was rapid; steady state was achieved within 5 min after the dose. Moxalactam showed essentially complete penetration into valve lesions, whereas concentrations in heart muscle were only 20% of those in serum. The physiological distribution of moxalactam in heart muscle was beyond the inulin space, but substantially lower than total body water. This myocardial distribution ratio was not predicted by the serum-free fraction or blood trapped in tissues alone, but was in good agreement with that of extracellular fluid plus blood trapped in tissues. The moxalactam distribution profile was most compatible with that of drugs which are excluded from cells but readily distributed throughout extracellular fluids. This explains its nearly complete penetration into heart valves as well as its incomplete penetration into heart muscle, since the two sites differ in their relative proportions of cells and extracellular fluid spaces.

Animals↗

PubMed1991

Drug distribution studies with microdialysis. III: Extracellular concentration of caffeine in adipose tissue in man.

Microdialysis was applied to estimate the extracellular concentration of caffeine in subcutaneous abdominal adipose tissue of five healthy volunteers after oral administration of approximately 5 mg/kg (300 or 400 mg) of caffeine. The peak extracellular levels were in the range of 20 - 80 microM. The time-course in blood and in extracellular fluid was similar but the plateau concentrations were not closely correlated. The estimated mean concentration of five individuals was similar in blood and extracellular fluid. The intraindividual variation between probes was found to be small compared to the interindividual variation (8% versus 43%). It is concluded that microdialysis yield useful data on drug distribution in man and that distribution to adipose tissue may not strictly follow the concentrations in blood. A comparison with available information of the in vitro properties of caffeine shows that the levels attained in the extracellular fluid were too small to significantly affect phosphodiesterase but sufficiently high to block adenosine receptors.

Adipose Tissue↗