Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Inulin”

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 1,045 records · Page 58Linked to original sources
PubMed1984

Examination of transepithelial exchange of water and solute in the rat renal pelvis.

Severance of the ureter beyond the renal papilla causes a fall in urinary osmolality, which suggests that exchange of water or solute between urine and renal parenchyma normally occurs in the intact renal pelvis. We examined water and solute flux in the renal pelvis with micropuncture and microcatheterization techniques. Four groups of antidiuretic rats were studied. Group I (n = 17) underwent micropuncture through the intact contracting ureter. Urine samples were obtained at the papillary tip, and in the pelvis beside the base of the extrarenal papilla. Urinary osmolality at the base, 880 +/- 97 mosmol/kg H2O (mean +/- SE), was less than that at the tip, 1,425 +/- 104 mosmol/kg H2O (P less than 0.005). In group II (n = 24), samples were analyzed for inulin and osmolality. In 15 rats (group IIA), comparison was made between base and tip samples. In the other nine animals (group IIB), comparisons were made among base, tip, and bladder samples and urea was also measured. In group II (A and B combined) urine-to-plasma (U/P) osmolality was lower at the base, 4.31 +/- 0.27, than at the tip, 6.08 +/- 0.23 (P less than 0.001), and U/P inulin was lower at the base, 192 +/- 25, than at the tip, 306 +/- 16 (P less than 0.001). In group IIB, the bladder urine had a lower U/P osmolality, 5.27 +/- 0.25, than the tip, 6.01 +/- 0.31 (P less than 0.02). The U/P urea was 59 +/- 10.6 (base), 98 +/- 9.4 (tip) (base vs. tip, P less than 0.05), and 81 +/- 6.5 (bladder, P less than 0.005, compared with tip). In group III (n = 8), samples were obtained by microcatheter from the fornices, the deepest intrarenal extensions of the pelvis, and compared with samples at the tip. Urinary osmolality was lower in the fornix, 646 +/- 106 mosmol/kg H2O, than at the tip, 1,296 +/- 99 mosmol/kg H2O (P less than 0.001). Similarly, U/P inulin was lower in the fornix, 48 +/- 14, than at the tip, 128 +/- 12 (P less than 0.001). The lower U/P inulin in the pelvic urine is the result of either the addition of fluid to the pelvis, or the backleak of inulin across the epithelium lining the pelvis. To verify that the pelvic epithelium was impermeable to inulin, in group IVA (n = 4) the left renal pelvis was superfused with a solution of chemical inulin. Cumulative absorption of inulin from the left kidney was 0.15 +/- 0.08% of that superfused. Using [14C]inulin in group IVB (n= 3), similar results were obtained (0.05 +/- 0.02%). These findings indicate that in the renal pelvis, fluid is added to urine after it emerges from the collecting ducts. We suggest that reflux of hyperosmotic urine over the renal papilla creates a transepithelial gradient for the flux of water into the pelvis. A model that incorporates diffusive and convective forces for water and solute transport is proposed to account for these findings.

Animals↗
PubMedDate not supplied

In vivo placental permeability to hydrophilic solutes as a function of fetal weight in the guinea pig.

The permeability of the placenta was measured with unlabelled inulin in unanaesthetized guinea pigs. Inulin was injected into the sows and the plasma concentrations were recorded at regular intervals. The inulin contents of the conceptuses were calculated from fetal weights, fetal plasma inulin concentrations and a measured inulin distribution volume of 180 ml/kg fetus. From fetal inulin contents and the time integral of the difference in maternal and fetal plasma concentrations, we calculated a mean inulin permeability of 29 +/- 9 (s.e.m.) nl/s per gram placental weight. The inulin permeability per gram placental weight rose statistically significantly with increasing fetal weight. Comparison with a similar rise observed for the smaller cyanocobalamin molecule studied previously led to the conclusions that in the last ten days of gestation the transplacental passages narrow while at the same time there are apparent changes in the numbers and/or lengths of these passages that suffice to increase the unrestricted permeability fourfold.

Animals↗
PubMed2002

Investigations into the stabilisation of drugs by sugar glasses: I. Tablets prepared from stabilised alkaline phosphatase.

The aim of this study was to investigate the formulation of sugar glass stabilised alkaline phosphatase from bovine intestine (BIAP) into tablets. Two major subjects of tablet formulation were investigated. First, the compaction behaviour of the inulin sugar glass was investigated. Secondly, the effect of the compaction process on the physical stability of sugar glass stabilised BIAP was investigated, comparing inulin and trehalose glass. The tabletting properties of freeze-dried inulin without BIAP were studied first. Freeze-dried inulin conditioned at either 20 degrees C/0% relative humidity (RH) or 20 degrees C/45% RH was compacted at various pressures. As expected, the yield pressure of the material conditioned at 0% RH was higher (68 MPa) than after conditioning at 45% RH (39 MPa). Tablets made of the material stored at 0% RH showed severe capping tendency, especially at high compaction pressures. In contrast, material conditioned at 45% RH gave tablets without any capping tendency and a friability of less than 1%. Sugar glasses of BIAP and either inulin or trehalose were prepared by freeze-drying (BIAP/sugar 1/19 (w/w)). The material was subsequently compacted. Tablets and powders were stored at 60 degrees C/0% RH. The activity of the incorporated BIAP was measured at various time intervals. It was found that inulin was by far superior to trehalose as stabiliser of BIAP in tablets. The poor stabilising capacities of trehalose after compaction are explained by crystallisation of trehalose induced by the compaction process and moisture in the material. The results clearly show that inulin is an excellent stabiliser for BIAP. The tabletting properties are adequate, showing sufficient tablet strengths and low friability. Furthermore, the good (physical) stability of inulin glass with respect to exposure to high relative humidities makes it practical to work with.

Alkaline Phosphatase↗
PubMed1998

The water-soluble extract of chicory influences serum and liver lipid concentrations, cecal short-chain fatty acid concentrations and fecal lipid excretion in rats.

Sprague-Dawley rats (n = 32) were fed diets without fiber (control) or containing 1 or 5% chicory extract or 5% inulin for 4 wk; 0.2% cholesterol was added to all diets. Rats fed chicory extract and inulin diets had significantly higher serum high density lipoprotein (HDL) cholesterol and generally lower low density lipoprotein (LDL) cholesterol concentrations, thus significantly greater ratios of HDL/LDL cholesterol compared with the controls (P < 0.05). The serum apolipoprotein B/apolipoprotein A-1 ratio was significantly lower in rats fed diets containing chicory extract or inulin than that in rats fed fiber-free diets, due to significant reductions in apolipoprotein B concentration (P < 0.05). Greater liver lipid and triglyceride concentrations were observed in rats fed chicory extract or inulin diets compared with the controls (P < 0.05). However, liver phospholipid and cholesterol concentrations were not significantly different among groups (P > 0.05). Addition of 5% inulin to the diet resulted in greater cecal weight, whereas both 5% chicory extract and 5% inulin resulted in greater cecal propionic acid concentration compared with the controls (P < 0.05). Rats fed chicory extract and inulin had significantly greater fecal lipid, cholesterol and bile acid excretions than those fed fiber-free diets (P < 0.05). The results of this study suggest that the improved lipid metabolism observed in rats fed chicory extract (mainly inulin component) may be caused by an alteration in the absorption and/or synthesis of cholesterol, which might result from the changes in cecal fermentation, and by an increase in the fecal excretion of lipid, cholesterol and bile acid.

Animals↗
PubMed1984

Prostaglandin I2 attenuates ischemic acute renal failure in the rat.

We gave prostaglandin I2 (PGI2) (8 ng X kg-1 X min-1 i.v.) for 20 min before, during, and 20 min after clamping of the rat left renal artery for 40 min to evaluate the effect of PGI2 in this model of acute renal failure. Control animals were given glycine buffer (PGI2 diluent). Glomerular filtration rate was estimated by the clearance of inulin 24 h later from each kidney. In group I rats (studied during hydropenia) inulin clearance in the control (right) kidney averaged 1.4 ml/min. Inulin clearance in kidneys exposed to 40 min of ischemia was 0.05 (glycine treated) versus 0.22 (PGI2 treated) ml/min. Although PGI2 offered significant protection in the group I animals, the differences were small and many of the glycine-treated ischemic kidneys were anuric. In the group II studies the same protocol was employed except that 5% body wt volume expansion was done with Ringer solution prior to measurement of inulin clearance. In the group II rats inulin clearance in control (right) kidneys averaged 1.5 ml/min. Inulin clearance after 40 min of renal ischemia was 0.04 ml/min in glycine-treated rats versus 0.90 ml/min in PGI2-treated animals. Histological examination of the group II ischemic kidneys revealed cellular necrosis and cast formation in the S3 segments of the glycine-treated animals and significantly less necrosis and cast formation in the PGI2-treated animals. The degree of necrosis and casts was inversely related to inulin clearance. Accordingly, PGI2 significantly attenuated the fall in inulin clearance measured 24 h after ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1980

Assessment of glomerular filtration rate in children.

Five different methods of assessment of glomerular filtration rate (GFR) were compared in 500 children older than one year of age. Results of each method were compared with standard inulin clearance values: 1. An evaluation of glomerular function may be inferred from plasma creatinine levels; the validity of this inference is, however, limited because of the wide range of normal values; 2. creatinine clearance values calculated over 3 hours significantly overestimate inulin clearance values; 3. clearance values derived from plasma creatinine concentration ahd height show a poor correlation with traditionally calculated inulin clearances; 4. clearance values calculated as the sum of twice the creatinine clearance and once the urea clearance, divided by three, better predict inulin clearance than either C-creatinine or C-urea alone; 5 inulin clearance values calculated by dividing the quantity of inulin perfused by its plasma concentration, once it has become stable, differ significantly from the values obtained by the standard inulin clearance.--Of all the methods studied, none was found to be an ideal alternative to the traditional inulin clearance when a precise assessment of GFR is warranted. It is concluded that in most clinical conditions derived clearance values do not have significant advantages over the simple determination of plasma creatinine, a valuable but not infallible index of glomerular function.

Adolescent↗
PubMed1994

Estimation of glomerular filtration rate and evaluation of renal function in ferrets (Mustela putorius furo).

Three methods of determining glomerular filtration rate (GFR) were performed in adult ferrets, 9 months to 7 years old. Endogenous creatinine clearance was determined, using serum and urine creatinine values obtained during 24- and 48-hour collection periods from 27 ferrets housed in metabolic cages. Creatinine and radiolabeled inulin were administered to 12 female ferrets by constant IV infusion during isoflurane-induced anesthesia. Serial 20-minute urine collections, together with serum samples obtained at the midpoint of urine collection, provided measures for clearance calculations of these substances. Mean +/- SD endogenous creatinine clearance in ferrets for metabolic cage collections was 2.50 +/- 0.93 ml/min/kg of body weight. There were no significant differences between the 24- and 48-hour clearance rates. Mean inulin clearance was 3.02 +/- 1.78, and mean exogenous creatinine clearance was 3.32 +/- 2.16 ml/min/kg. Analysis of variance, using least-squared means adjustment, did not yield any significant differences between inulin and exogenous creatinine clearance rates. Exogenous creatinine clearance-to-inulin clearance ratio was 0.99 +/- 0.46, and there was significant correlation between the 2 methods (r = 0.82, P = 0.0001). Significant body temperature effects on inulin or exogenous creatinine clearance were not found. Infused inulin clearance, the generally preferred method for GFR calculation in mammalian species, was significantly (P = 0.0069) higher in younger (3.65 ml/min/kg) vs older ferrets (2.29 ml/min/kg). Results of this study indicate that inulin clearance is an adequate measure of GFR in ferrets as it is in other species. Compared with inulin clearance, exogenous creatinine clearance also provides a reliable estimate of GFR in ferrets.

Aging↗
PubMed1998

Glomerular filtration rate measurement in cirrhotic patients with renal failure.

Assessment of renal function, namely glomerular filtration rate (GFR), by the renal creatinine clearance, may be problematic and less accurate in cirrhotics; however, it is an essential element in the global evaluation of these patients. In order to better characterize misinterpretation of GFR by the renal creatinine clearance, we compared a group of cirrhotic patients with renal failure (n - 30) to a group of chronic renal failure patients (CRF) without liver disease (n - 5). Inulin and PAH clearances were measured during a 4-hour infusion of inulin and PAH; renal creatinine clearance was measured during a 24-hour urine collection and this, simultaneously with inulin and PAH clearance. We observed that in moderate to severe renal failure (renal inulin clearance 30 +/- 10 ml/min), GFR (i. e. renal inulin clearance) in cirrhotic patients was overestimated by the renal creatinine clearance, similarly to CRF patients (ratio 1.8 +/- 0.7 and 1.6 +/- 0.9 respectively); however cirrhotic patients have a lower serum creatinine (186 +/- 97 vs 133 +/- 62 micromol/l respectively). On the other hand, cirrhotic patients with mild renal dysfunction (renal inulin clearance 74 +/- 15 ml/min) had a renal creatinine clearance of 77 +/- 25 ml/min. Systemic inulin clearance overestimated renal inulin clearance, proportionally to the severity of renal dysfunction. We conclude that it is only the degree of renal failure, irrespective of etiology, that explains the overestimation of the glomerular filtration rate by the renal creatinine clearance in cirrhotic patients; hence, there is no specific alteration in the renal excretion of creatinine in cirrhotic patients.

Creatinine↗
PubMed1999

How to assess glomerular function and damage in humans.

In human subjects, the assessment of renal function and of its changes by interventions is limited to the measurement of glomerular filtration rate (GFR), renal blood flow and the estimation of proteinuria. In humans, GFR can be determined exactly by measuring the clearance of an ideal filtration marker, such as inulin. The classic method of measuring inulin clearance in humans includes constant intravenous infusion of the compound and timed collections of urine. In order to avoid the need for timed urine collections, a number of alternative procedures have been devised. All these methods only use determinations of inulin in plasma or serum. From these, the total body inulin clearance is obtained using pharmacokinetic calculations. In order to measure total body clearance, usually called plasma clearance, inulin is either given as a constant intravenous infusion or as a bolus infusion. Both procedures overestimate GFR because of incomplete distribution of inulin during the study periods. The error may be minimized by using model-independent pharmacokinetic calculations. Unlike inulin, creatinine is not a perfect filtration marker. This is because the substance is not only eliminated by glomerular filtration but also by tubular secretion. The extent of tubular creatinine secretion is not constant in various individuals. Serum creatinine concentration is a commonly used measure of renal function in clinical practice. This parameter is determined both by the renal elimination and by the production of the compound. Differences in creatinine production among subjects and over time in a single individual may occur because of changes in muscle mass. Radioisotopic filtration markers can easily and accurately be measured in plasma and serum. Using this method, the plasma concentration-time curve of these compounds can easily be studied after intravenous bolus injection. From the plasma concentration-time curves obtained, the total body clearance (plasma clearance) of the substances can be calculated using pharmacokinetic models. Most frequently, 125l-iothalamate, 99mTc-diethylenethiaminepenta-acetic acid and 51Cr-ethylenediaminetetra-acetic acid are used for the estimation of GFR in humans. The total body clearance of all these filtration markers overestimates GFR. The error induced by this phenomenon is particularly relevant at low levels of GFR. In recent years, iohexol has been used as a filtration marker. The substance can be measured in plasma, serum and urine using high-performance liquid chromatography. So far, good agreement has been shown for GFR determined by the classic inulin clearance and by the iohexol plasma clearance. Screening for proteinuria is commonly performed using reagent test strips. Quantitative measurements of marker proteins can be used to estimate the extent and the site of damage in the nephron. These measurements may be used to estimate the progression of renal disease and the response to therapeutic interventions. Of particular interest is the degree of albuminuria which indicates nephropathy in diabetic patients and end-organ damage in patients with hypertension.

Humans↗
PubMed1979

Renal elimination kinetics and plasma half-life of oxalate in man.

The renal handling of oxalate was studied by the injection of 14C-oxalate together with inulin as a glomerular marker into the renal artery in 6 patients. From the recovered amounts of the injected substances in the urine, time-concentration curves were constructed. Oxalate was excreted into urine 2.31 +/- 0.05 (SE) fold when compared to inulin. The maximal concentration of oxalate occurred at the same time as inulin, and there was no urinary precession of oxalate in comparison to inulin. From this part of the study we conclude that oxalate in addition to its filtered amount can probably enter the early part of nephron. In a second type of study, plasma levels of oxalate and inulin were observed over a period of 180 min, following intravenous injections in 7 volunteers. The decline of oxalate plasma concentrations followed first-order kinetics. Calculation of the rate constants of elimination assuming the 'one compartment open' model resulted in an oxalate to inulin ratio of 1.21 +/- 0.05. The oxalate half-life of elimination was 92 +/- 8 min, whereas that of inulin amounted to 112 +/- 9 min. The higher value of the calculated volume of distribution of oxalate compared to that of inulin indicates that oxalate enters a larger space than the extracellular fluid volume. The urinary recovery of intravenously injected oxalate was 97.2 +/- 1.4%, indicating that oxalate is excreted exclusively by the kidney. The observed differences of oxalate excretion, obtained with these two methods, could be attributed to the higher amount of ionized oxalate in the disequilibrium technique (rapid injections), entering the urine in a higher rate. Such a mechanism could explain the hyperoxaluria in calcium oxalate stone-forming patients.

Half-Life↗
PubMed1981

Abnormalities of volume regulation and membrane integrity in myocardial tissue slices after early ischemic injury in the dog: effects of mannitol, polyethylene glycol, and propranolol.

The authors used an in vitro myocardial tissue slice technique to quantitate the transmural distribution of alterations in cell volume regulation and membrane integrity following early ischemic injury and to evaluate directly the effects of therapeutic interventions in a system not subjects to influences of coronary blood flow. Left circumflex coronary occlusion was produced in 57 dogs for 30 or 60 minutes. After in vitro incubation in Krebs-Ringer-phosphate-succinate medium containing trace 14C-inulin, typical values (ml H2O/g dry weight) for control nonischemic myocardial slices were 3.68 +/- 0.07 (SEM) for total tissue water, 2.67 +/- 0.07 for inulin impermeable space, and 1.01 +/- 0.04 for inulin diffusible space. Ischemic myocardial slices exhibited an impaired response to cold shock (0 C for 60 minutes) and rewarming (37 C for 60 minutes). After 60 minutes coronary occlusion, respective increases in total tissue water, inulin-impermeable space and inulin-diffusible space of ischemic slices were 25.5 +/- 2.6%, 6.2 +/- 4.9% and 84.4 +/- 12.5% for papillary muscle, 22.2 +/- 2.1%, 10.4 +/- 4.2% and 52.5 %/- 10.3% for subendocardium and 9.1 +/- 1.5%, 7.2 +/- 2.3% and 15.8 +/- 5.5% for subepicardium. Significant but usually less marked alterations occurred after 30 minutes of coronary occlusion. Propranolol treatment in vivo (2 mg/kg) and/or in vitro (0.01 mg/ml medium) produced no significant changes in tissue water or inulin spaces of ischemic slices, compared with saline controls. Incubation in hyperosmolar mediums resulted in significant reductions in total tissue water and inulin-impermeable space with little change in inulin-diffusible space of both ischemic and control slices. Fifty milliosmolar polyethylene glycol (MW 6000) produced a greater reduction in tissue water and ultrastructural evidence of cell swelling than did either 40 or 100 milliosmolar mannitol (MW 182). The major effect of hyperosmolar incubation appeared to be a selective reduction in edema of cells with structurally intact membranes. Thus, in vitro studies, with myocardial tissue slices provide evidence of widespread alterations of membrane integrity after 30--60 minutes of in vivo coronary artery occlusion. In vitro abnormalities of cell volume regulation can be partially reversed by direct osmotic effects on myocardial cells.

Animals↗
PubMedDate not supplied

Permeability characteristics of the guinea pig biliary apparatus.

To determine the mechanism and pathway of entry of polar nonelectrolytes into bile, we studied first the permeation of [3H]H2O, [14C]urea, [14C]erythritol, [14C]mannitol, [3H]sucrose, [3H]inulin and [3H]dextran across an isolated, in situ perfused segment of the guinea pig's extrahepatic bile duct. All of these molecules, except [3H]dextran, permeated the bile duct. The diffusive permeability coefficients (cm per sec per 10(6) ranged from 248 for [3H]H2O to 1.2 for [3H]inulin. On the basis of these results, we formulated two models of solute biliary excretion. In Model I, permeation across both the canaliculus and ductule/duct was assumed to be by simple diffusion. In Model II, solute was assumed to enter the canaliculus by convection and diffusion, and the ductule/duct by diffusion. Reflection coefficients and/or permeability coefficients for the canalicular membrane were then determined by fitting the equations describing these processes to the bile-to-plasma ratios of [14C] erythritol, [14C]mannitol, [3H]sucrose and [3H]inulin observed at different rates of bile flow produced by partially clamping the bile duct cannula and subsequently infusing taurodehydrocholate. Only when convection was included as a mechanism of canalicular permeation (Model II) was excellent fitting observed. In such a case, the reflection coefficients and permeability coefficients for the carbohydrates in question were similar to those reported for other transporting epithelia. Cholestasis produced by taurolithocholate (10 to 40 mumoles per kg, i.v.) was associated with an irreversible increase in both the sieving coefficient and permeability coefficient for [3H]sucrose and [3H]inulin, even when the inhibition of bile flow was fully reversible. The permeability to [14C] erythritol and [14C]mannitol was either not affected or minimally increased. These findings suggest that, in the guinea pig: solutes as large as [3H]inulin enter the biliary tree both at the canaliculus and bile ductule/duct; [14C]erythritol and [14C]mannitol gain access into the canalicular lumen primarily by convection, whereas [3H]sucrose and [3H]inulin permeate mainly by diffusion; distal permeation of these carbohydrates is small, and accounts for 1 to 11% of their total biliary entry; the canalicular membrane permeability to [3H]sucrose and [3H]inulin is not functionally important in bile secretion, and a fraction of canalicular bile flows through the transjunctional shunt pathway.

Animals↗
PubMed1993

Rats discriminate between starch and other substances having a similar texture.

Studies examined the contribution of textural factors to the ability of rats to sense starch. If rats sense the abrasive effects of starch suspensions, conditioned aversions to starch should generalize to substances having a similar texture. Two substances having a texture similar to that of starch were examined, polymeric dialdehyde (a product derived from starch) and inulin (a polymer of fructose). Rats were trained to avoid dilute suspensions of rice starch, potato starch, polymeric dialdehyde, or dahlia inulin, by injecting them with lithium chloride after they drank the test substance. Generalization tests revealed that rats trained to avoid rice or potato starch subsequently avoided corn starch, whereas rats trained to avoid polymeric dialdehyde or dahlia inulin did not avoid corn starch. Rats trained to avoid polymeric dialdehyde avoided this substance to a greater degree than did rats trained to avoid rice or potato starch. Rats trained to avoid dahlia inulin avoided this substance to a greater degree than did the rats in the other groups, but avoidance of dahlia inulin did not generalize to chicory inulin. Untrained rats showed little or no preference for dilute suspensions of polymeric dialdehyde or inulin, but did prefer starch over vehicle. It is concluded that tactile sensitivity does not play a large role in the perception of dilute starch suspensions.

Animals↗
PubMed1992

Comparison of three methods of glomerular filtration rate measurement with and without captopril pretreatment in groups of patients with left ventricular dysfunction.

Methods of glomerular filtration rate measurement by 51Cr EDTA elimination, inulin clearance and creatinine clearance were compared with and without captopril pretreatment in 10 chronic heart failure patients and in 20 patients after transmural myocardial infarction. Strong intermethod correlations were found in chronic heart failure patients (EDTA: inulin r = 0.87; EDTA: creatinine r = 0.84; inulin: creatinine r = 0.9; all P less than 0.00001). Despite this, substantial absolute differences were observed in results obtained by different techniques. In particular, creatinine clearance significantly overestimated both 51Cr EDTA (18.0 +/- 18.4 ml.min-1, mean difference +/- SD, P less than 0.001) and inulin clearance (26.8 +/- 17.0 ml.min-1, P less than 0.001). The slight reduction in 51Cr EDTA elimination on captopril versus placebo (-8.3 +/- 9.2 ml.min-1, P less than 0.05) was related to a similar treatment difference in inulin clearance (r = 0.67, p = 0.03), but changes observed by either method were unrelated to captopril-induced changes in creatinine clearance. Thus, creatinine clearance is an unsatisfactory means of assessing the effect of angiotensin converting enzyme inhibition on glomerular filtration rate in chronic heart failure. In the post-myocardial infarction group, correlations between methods were poorer (EDTA: inulin r = 0.79; EDTA: creatinine r = 0.76; inulin: creatinine r = 0.67). In this group no significant effect of captopril on glomerular filtration rate was detected by any technique. As compared to the chronic heart failure patients, the weaker relationship between techniques post-myocardial infarction may be related to interference by thrombolytic or aspirin treatment.

Captopril↗
PubMed1993

Predictability of creatinine clearance estimates in critically ill patients.

OBJECTIVES: a) To evaluate the predictive ability of different creatinine clearance methods as compared with the criterion standard, inulin clearance; and b) to determine which of the predictive methods yields the most accurate estimation of creatinine clearance. DESIGN: Prospective study. SETTING: Medical intensive care unit (ICU) of a university-affiliated tertiary care hospital. INTERVENTIONS: Glomerular filtration rate was measured by the criterion standard, inulin clearance. PATIENTS: Twenty mechanically ventilated adults. MEASUREMENTS: Renal function was assessed by the following procedures: inulin clearance using a standard protocol, 30-min creatinine clearance, 24-hr creatinine clearance, and creatinine clearance estimates by the Cockcroft-Gault equation. Ideal body weight, total body weight or lean body mass with actual serum creatinine or serum creatinine concentration corrected to 1 mg/dL (85 mumol/L) in cachectic patients were sequentially incorporated into the Cockcroft-Gault equation. RESULTS: The Cockcroft-Gault equation, using ideal body weight and the corrected serum creatinine concentration, was the best predictor of inulin clearance with the smallest bias (9.7 +/- 8.6, 95% confidence interval 5.7 to 13.8). The bias encountered with the 30-min creatinine clearance was not different from that value with the 24-hr creatinine clearance (21.6 +/- 33.0, 95% confidence interval 6.2 to 37.1 vs. 25.4 +/- 28.3, 95% confidence interval 11.8 to 42.9). Good correlations existed between inulin clearance and the Cockcroft-Gault equation, using ideal body weight and the corrected serum creatinine concentration (r2 = .81; p = .0001), as well as between inulin clearance and the Cockcroft-Gault equation, using the lower of ideal or total body weight and the higher of the actual serum creatinine concentration or corrected serum creatinine (r2 = .75; p = .0001). The 30-min creatinine clearance and the 24-hr creatinine clearance had poorer agreement with inulin clearance. The incorporation of a corrected serum creatinine value into the Cockcroft-Gault equation consistently led to better predictions and higher correlation coefficients. CONCLUSIONS: The utilization of the Cockcroft-Gault equation as used clinically (the lower of ideal or total body weight and the higher of actual serum creatinine or corrected serum creatinine concentration to 1 mg/dL [85 mumol/L]) results in more accurate predictions of glomerular filtration rate in the medical, critically ill patient than urine creatinine clearance measures. If creatinine clearance measures are used, the 30-min collection provided results not different from those results obtained with 24-hr urinary collections.

Adult↗
PubMed1974

Extracellular space in some isolated tissues.

1. The spaces occupied by isotopically labelled inulin, polyethylene glycol, mol. wt. 4000 (PEG 4000), polyethylene glycol, mol. wt. 1000 (PEG 1000) and sucrose in metabolizing mammalian kidney and liver slices and in toad bladder epithelial cell preparations incubated in vitro have been examined.2. In slices of mammalian tissue, and in homogenized liver, it proved impossible to extract inulin completely from tissue which had been dried. However, inulin was recovered as completely from both dried and undried toad bladder epithelial cells scraped from hemibladders incubated in vitro.3. PEG 4000 occupied a space in all preparations similar to that from which inulin was extracted in dried tissue.4. PEG 1000 and sucrose entered cellular water in mammalian slices, but PEG 1000 occupied a similar space to inulin in toad bladder epithelial cell preparations.6. It is concluded that inulin enters cellular water in mammalian slices from which after drying of the slices it cannot be extracted. It thus rather fortuitously provides a measure of extracellular water under these conditions. In preparations of toad bladder epithelial cells inulin seems to be a satisfactory extracellular marker. PEG 4000, which did not appear to enter cellular water also allows a reasonable estimate of extracellular water. PEG 1000 is a suitable extracellular marker for toad bladder epithelial cell preparations but not for mammalian slices. Sucrose entered cellular water in both slices and toad bladder epithelial cells and is not a satisfactory extracellular marker in these tissues.

Age Factors↗
PubMed1987

Hemorrhagic shock impairs myocardial cell volume regulation and membrane integrity in dogs.

An in vitro myocardial slice technique was used to quantitate alterations in cell volume regulation and membrane integrity after 2 h of hemorrhagic shock. After in vitro incubation in Krebs-Ringer-phosphate medium containing trace [14C]inulin, values (ml H2O/g dry wt) for control nonshocked myocardial slices were 4.03 +/- 0.11 (SE) for total water, 2.16 +/- 0.07 for inulin impermeable space, and 1.76 +/- 0.15 for inulin diffusible space. Shocked myocardial slices showed impaired response to cold incubation (0 degrees C, 60 min). After 2 h of in vivo shock, total tissue water, inulin diffusible space, and inulin impermeable space increased significantly (+19.2 +/- 2.4, +8.1 +/- 1.9, +34.4 +/- 6.1%, respectively) for subendocardium, whereas changes in subepicardium parameters were minimal. Shock-induced cellular swelling was accompanied by an increased total tissue sodium, but no change in tissue potassium. Calcium entry blockade in vivo (lidoflazine, 20 micrograms X kg-1 X min-1 during the last 60 min of shock) significantly reduced subendocardial total tissue water as compared with shock-untreated dogs. In addition, calcium entry blockade reduced shock-induced increases in inulin impermeable space and inulin diffusible space. In vitro myocardial slice studies confirm alterations in subendocardial membrane integrity after 2 h of in vivo hemorrhagic shock. Shock-induced abnormalities in myocardial cell volume regulation are reduced by calcium entry blockade in vivo.

Anesthesia↗
PubMed1976

Renal tubular transport of 3H-digoxin in saline diuresis in rats.

We evaluated urinary excretion and tubular transport of 3H-digoxin by three different methods in anesthetized rats made diuretic by infusion of 2.5% saline. In one group small volumes of 3H-digoxin and 14C-inulin were injected simultaneously into surface proximal convolutions, and urine was collected serially from both ureters. Digoxin recovery was lower after early (62.1 +/- 5.3%) than after late (86.9 +/- 7.7%) proximal administration but inulin recovery was complete (99.6 +/- 2.7%) after all injections. Most of the digoxin was excreted simultaneously with inulin. Delayed recovery was low. In another group of rats digoxin and inulin were applied directly to the capsule of the left kidney. Two-thirds of the recovered digoxin appeared from the left ureter and one-third from the right. The difference (41.9 +/- 7.4%) is an estimate of transtubular digoxin influx. Digoxin excretion preceded inulin only on the left. Digoxin to inulin concentration ratios were 6 times higher from the left than the right, whereas inulin recoveries from the two sides were similar. In a third group of rats tubular fluid was collected from surface convolutions of proximal and distal tubule. In the accessible segment of the proximal tubule 35.9% of the filtered digoxin was reabsorbed. In the more distal nephron, drug was added into the lumen; this resulted in a net urinary excretion of 80.2 +/- 18.2%. These findings are compatible with free filtration of digoxin at the glomerulus followed by passive proximal tubular reabsorption and an influx against a concentration gradient in the distal nephron.

Animals↗