[Glomerular filtration and inulin clearance in normal and adrenalectomized rats].
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Adrenalectomy↗
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[Study of inulin and PAH clearances, cardiac output, exchangeable Na and K and extracellular fluids during the development of liver cirrhosis].
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Adult↗
Determination of inulin clearance by using a single-sample method.
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Adolescent↗
[Inulin induced platelet aggregation in patients with paroxysmal nocturnal haemoglobinuria (author's transl)].
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Blood Platelets↗
Factors influencing the insulin space in cerebral cortex slices from adult and 7-day-old rats.
The inulin spaces and swelling of brain cortex slices from adult and 7-day-old rats were measured under differing experimental conditions. At 37 degrees C inulin penetrated into larger compartments than at 0 degrees C in both age groups. At 37 degrees C the inulin space increased with decreasing concentration of inulin in the medium. At 0 degrees C the inulin space did not depend on the inulin concentration. The swelling of the slices at 37 degrees C diminished with increasing concentrations of inulin. Anaerobic conditions, 0.2, and 1.0 mmol/l sodium cyanide and 0.1 mmol/l dinitrophenol reduced the inulin space and caused increased swelling of the slices. 1.0 mmol/l sodium iodoacetate was ineffective. In anaerobic conditions the inulin space did not change significantly as a function of the inulin concentration. A serious disadvantage of the inulin space as an indicator of extracellular space is that its size depends on the inulin concentration used. The inulin itself may influence the size of the space to be measured. Inulin also in osmotically inactive concentrations considerably reduces the swelling of brain cortex slices.
Age Factors↗
Localization of inulinase and invertase in Kluyveromyces species.
In vivo hydrolysis of inulin and sucrose was examined in selected yeasts of the genus Kluyveromyces. Cells, grown in sucrose-limited chemostat cultures, were subjected to treatments for the removal of inulinase, the enzyme responsible for the hydrolysis of both inulin and sucrose. The effects of these treatments were studied by measurement of inulin-dependent and sucrose-dependent oxygen consumption by cell suspensions. In Kluyveromyces marxianus var. marxianus, inulinase was partially secreted into the culture fluid. Removal of culture fluid inulinase by washing had no effect on sucrose-dependent oxygen consumption by this yeast. However, this treatment drastically reduced inulin-dependent oxygen consumption. Treatment of washed cells with sulfhydryls removed part of the cell wall-retained inulinase and reduced inulin-dependent oxygen consumption by another 80%. Sucrose-dependent oxygen consumption was less affected, decreasing by 40%. Cell suspensions of K. marxianus var. drosophilarum, K. marxianus var. vanudenii, and Saccharomyces kluyveri rapidly utilized sucrose but not inulin. This is in accordance with the classification of these yeasts as inulin negative. Supernatants of cultures grown at pH 5.5 did not catalyze the hydrolysis of inulin and sucrose. This suggested that these yeasts contained a strictly cell-bound invertase, an enzyme not capable of inulin hydrolysis. However, upon washing, cells became able to utilize inulin. The inulin-dependent oxygen consumption further increased after treatment of the cells with sulfhydryls. These treatments did not affect the sucrose-dependent oxygen consumption of the cells. Apparently, these treatments removed a permeability barrier for inulin that does not exist for sucrose.(ABSTRACT TRUNCATED AT 250 WORDS)
Cell Wall↗
Measurement of glomerular filtration rate in children with insulin-dependent diabetes mellitus.
51Cr-EDTA, inulin and creatinine clearances were measured simultaneously in 11 diabetic children and 12 healthy young adults. The clearances in all individuals were 115 +/- 24 ml/min per 1.73 m2SA for 51Cr-EDTA, 118 +/- 25 ml/min per 1.73 m2SA for inulin and 157 +/- 35 ml/min per 1.73 m2SA for creatinine. Values were higher in the diabetic children but the differences were not significant. 51Cr-EDTA clearance significantly underestimated that of inulin by a mean of -7.4 +/- 2.5 (SEM) ml/min per 1.73 m2SA (p less than 0.01) and creatinine clearance significantly overestimated that of inulin by 37.6 +/- 3.3 (SEM) ml/min per 1.73 m2SA (p less than 0.0001). Similarly, the mean ratio of 51Cr-EDTA to inulin clearance was 0.94 (95% CI 0.90-0.98) and that of creatinine to inulin clearance was 1.32 (95% CI 1.27-1.37); the differences between diabetics and controls were not significant. Correlation coefficients were 0.93 between 51Cr-EDTA and inulin clearances, and 0.95 between inulin and creatinine clearances. The pooled coefficient of variation between clearances within an individual was higher with inulin, 10.3 +/- 6.5% (SD), than 51Cr-EDTA, 7.3 +/- 5.1% (p less than 0.001, t test). These results show that 51Cr-EDTA clearance underestimates that of inulin to a similar extent in both diabetic children and healthy controls and creatinine clearance overestimates inulin clearance to a greater but similar extent in both groups. The methodological variation in 51Cr-EDTA measurement is less than with the other 2 methods. Therefore, we recommend the use of the renal clearance of 51Cr-EDTA for the measurement of GFR in diabetic children.
Adolescent↗
Intracellular delivery of membrane-impermeable hydrophilic molecules to a hepatoblastoma cell line by asialoglycoprotein-labeled liposomes.
BACKGROUND AND PURPOSE: Mammalian hepatic receptors are specific for the terminal D-galactose of desialylated glycoproteins. This study used asialofetuin-labeled liposomes (AF-liposomes) to target hepatoma cells using this receptor mechanism, and investigated their efficiency in intracellular delivery of membrane-impermeable hydrophilic molecules to a hepatoblastoma cell line (HepG2). METHODS: Inulin was used as a model molecule. Blank liposomes consisting of phosphatidylcholine:phosphatidic acid:cholesterol in 6:1:6 molar ratio were prepared. Palmitoyl-asialofetuin was anchored onto the blank liposomes using a detergent dialysis method. 3H-inulin was entrapped in the AF-liposomes by dehydration (freeze-drying) and rehydration followed by freeze-thaw sonication. Plain liposomes (N-liposomes) were prepared by the same process but without AF. HepG2 cells were incubated for 3 hours with free 3H-inulin, N-liposomal 3H-inulin, AF-liposomal 3H-inulin, or free AF. The cellular uptake of 3H-inulin and the cell viability were then determined. Uptake of AF-liposomes in a non-hepatoma cell line, NIH3T3, was also studied for comparison. RESULTS: Cellular uptake of free inulin was negligible while uptake of liposomal inulin, either in N-liposomes or in AF-liposomes, was significant (p < 0.01). The uptake of AF-liposomal inulin was significantly higher than that of N-liposomal inulin in HepG2 cells but not in NIH3T3 cells. Free AF and blank AF-liposomes inhibited the HepG2 cell uptake of AF-liposomal inulin. CONCLUSIONS: These results indicate that AF-liposomes enhanced intracellular delivery of a membrane-impermeable hydrophilic drug into hepatoma cells by a receptor mechanism. AF-liposomes are a potential drug carrier for intracellular delivery of membrane-impermeable hydrophilic drugs to HepG2 cells.
3T3 Cells↗
Endogenous creatinine clearance measurement of glomerular filtration rate in dogs.
Renal clearance procedures were performed on adult mixed-breed dogs with a wide range of renal function. Endogenous creatinine clearance was computed after analyzing plasma and urine for creatinine by use of 2 methods, PAP and kinetic Jaffe. For 20-minute clearance procedures, [14C]inulin clearance was measured simultaneously with endogenous creatinine clearance. For 111 twenty-minute clearance procedures performed on 24 dogs, [14C]inulin clearance was highly correlated with creatinine clearance for both methods of creatinine analysis (R2 = 0.979 for [14C]inulin-PAP; R2 = 0.943 for [14C]inulin-Jaffe). The absolute values for PAP and [14C]inulin clearance were nearly the same (PAP-to-[14C]inulin clearance ratio = 1.03 +/- 0.08), but those for Jaffe clearance were substantially less than those for [14C]inulin clearance (Jaffe-to-[14C]inulin clearance ratio = 0.88 +/- 0.10). The Jaffe-to-[14C]inulin clearance ratio was inversely correlated with degree of renal function (R2 = 0.464), whereas the PAP-to-[14C]inulin clearance ratio was not correlated with degree of renal function (R2 = 0.060). Thus, Jaffe-determined creatinine clearance varied, in relation to [14C]inulin clearance, depending on degree of renal function. In 4 clinically normal dogs, 20-minute and 24-hour sample collections analyzed by use of the PAP method gave clearance values significantly greater, for both periods, than did Jaffe analyses. The PAP-determined creatinine clearance values were less than, but not significantly different from 20-minute exogenous creatinine clearance values determined 10 days after 24-hour collections.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Fluid phase endocytosis by cultured rat hepatocytes and perfused rat liver: implications for plasma membrane turnover and vesicular trafficking of fluid phase markers.
Hepatocytes take up a variety of ligands via receptor-mediated endocytosis, yet little is known regarding either the volume of fluid or the amount of membrane internalized via endocytosis in liver cells. In these studies, we have utilized radiolabeled inulin to characterize fluid phase endocytosis by rat hepatocytes in primary culture and perfused rat liver. Uptake of inulin by cultured hepatocytes was nonlinear with time, occurring most rapidly during the first 2 min. Inulin uptake and efflux in cultured hepatocytes and inulin uptake by perfused rat liver were kinetically compatible with the entry of inulin into a rapidly (t1/2, 1-2 min) turning-over (presumably endosomal) compartment that exchanged contents with the extracellular space and comprised approximately 3% of hepatocyte volume, as well as entry into and concentration of inulin within slowly (t1/2, greater than 1 hr) turning-over storage compartments. Based on inulin uptake, it is estimated that cultured hepatocytes endocytosed the equivalent of 20% or more of their volume and 5 or more times their plasma membrane surface area each hour. Neither chloroquine (1 mM) nor taurocholate (200 microM) affected inulin handling by cultured cells, whereas colchicine (10 microM) inhibited transfer to storage compartments by greater than 50%. In conjunction with our previous observations, the present findings suggest that inulin endocytosed across the basolateral membrane is largely (congruent to 80%) regurgitated back into plasma, with smaller amounts transported to intracellular storage compartments (congruent to 18%) or to bile (congruent to 2%). Transport of inulin via these pathways is unaffected by taurocholate and does not require vesicle acidification, whereas intact microtubular function is required for transfer to storage compartments or biliary secretion.
Animals↗
In vivo evaluation of a colonic delivery system using isotope techniques.
AIM: To evaluate, using isotope techniques, the in vivo effectiveness of a pH-dependent colonic delivery system. METHODS: In order to dispose of differently labelled substrates for measurement of orocaecal transit time, inulin-14C-carboxylic acid was evaluated as an alternative substrate to inulin and lactose-13C-ureide. Secondly, the time of release of 13C- and 15N-urea from the colonic delivery system was compared with the orocaecal transit time, measured using inulin and inulin-14C-carboxylic acid. This study was repeated after a 2-week lactulose intake period. RESULTS: The orocaecal transit time determined using inulin-14C-carboxylic acid (398 min) was not significantly different from the orocaecal transit time determined using inulin (420 min) or lactose-13C-ureide (396 min). Before lactulose intake, the 13CO2 excretion time was 358 min and the orocaecal transit times determined with the inulin-14C-carboxylic acid and inulin breath test were 376 and 375 min respectively. After lactulose, the 13CO2 excretion time was 383 min and orocaecal transit times were 354 min for inulin-14C-carboxylic acid and 392 min for inulin. A highly significant correlation was found. Good agreement was found between the urinary 15N excretion and the appearance of 13CO2 in breath. CONCLUSION: Isotope techniques provide an excellent non-invasive tool for the in vivo evaluation of a colonic delivery system.
Adult↗
Influence of variety, date of harvest and storage time on factors connected with the crystallisation on canned scorzonera (Scorzonera hispanica).
In the period 1983-1986, research was carried out into the inulin content of scorzonera during ripening and storage. Since the inulin content is determining for the occurrence of crystallisation with canned scorzonera, the effects of the varieties, the time of harvest and storage of the scorzonera were investigated. The changing of the inulin content on the conversion into reducing sugars was checked; the effect of the dry matter and nitrate content were also defined. The aim was to define whether the determination of the inulin content was a useful parameter for the ripening of the scorzonera. On the whole, the different varieties showed remarkable differences where fructosanes + inulin, as well as pure inulin, were concerned. A significant decrease of the inulin content was obtained from the middle of November, by so far that it was below the limit above which crystallisation takes place. A two-month storage period of scorzonera harvested in early October also led to a very low inulin content, so that no problems could occur while canning. Storage conditions of the scorzonera seemed of importance too. The nitrate content of the different scorzonera varieties was low, although some variations were noted. The crops harvested in early December showed considerably lower contents when compared to those harvested in early October or mid-November. The inulin content as well as the content of reducing sugars are a useful parameter to determine the maturity of the scorzonera.
Carbohydrates↗
Endocytosis in the amphibian oocyte. Effect of insulin and progesterone on membrane and fluid internalization during the meiotic divisions.
Endocytosis has been studied in the denuded Rana pipiens oocyte using 3H-labeled inulin. Internalization of labeled inulin is linear after the first 10-15 min and uptake into the cytoplasm is temperature-dependent and is blocked by 15 microM cyanide. Uptake occurs without hydrolysis of the inulin and varies exponentially with the concentration of inulin in the medium. Based on specific activity of the medium and inulin uptake into the cytoplasm, it is estimated that a fluid volume of about 20-25 nl is internalized per oocyte per hour. This fluid phase uptake corresponds to a half-time of about 35 h for turnover of the oocyte fluid phase. An estimate of membrane area based on endocytotic vesicle size from electron micrographs suggests that the entire oocyte plasma membrane recycles several times an hour. A fraction (15-20%) of the inulin taken up is associated with the plasma-vitelline membrane complex and uptake into the membrane complex parallels uptake into the cytoplasm. Insulin (a meiotic agonist) concentrations that induce plasma membrane hyperpolarization over the first h also stimulate [3H]inulin uptake into both the oocyte cytoplasm and membrane complex over the same time period. Progesterone (the physiological inducer) has no effect on inulin uptake during the first hour, but by 16-17 h after exposure to progesterone, inulin uptake is significantly enhanced. These results suggest that hormones such as insulin and progesterone may regulate membrane permeability by a programmed internalization and possible recycling of the plasma membrane components.
Animals↗
The in vitro evaluation of 'azo containing polysaccharide gels' for colon delivery.
This study reports on 'azo-polysaccharide gels', more specifically azo-inulin and azo-dextran gels, for colon drug delivery. Compared with azo-hydrogels which can be only degraded by reduction of the azo-groups, this study evaluates whether, in vitro, azo-polysaccharide gels can be degraded through both reduction of the azo-groups in the crosslinks as well as enzymatic break down of the polysaccharide backbone. The azo-polysaccharide gels were synthesized by radical crosslinking of a mixture of methacrylated inulin or methacrylated dextran and N,N'-bis(methacryloylamino)azobenzene (B(MA)AB) and were characterized by dynamic mechanical analysis and swelling measurements. Azo-dextran gels could be obtained from methacrylated dextran having low degree of substitution but not from lowly substituted methacrylated inulin. Increasing the amount of B(MA)AB resulted in denser azo-inulin and azo-dextran networks. Compared with their swelling in dimethylformamide, all azo-dextran gels became more swollen in water while azo-inulin gels shrank upon exposure to water, indicating a more hydrophobic character of the azo-inulin gels. Break down of the inulin and dextran chains in the azo-polysaccharide gels by inulinase and dextranase, respectively, was observed. However, the degradation of azo-dextran gels by dextranase seemed to be more pronounced than the degradation of the azo-inulin gels by inulinase. In rat caecal content medium, reduction of the azo function in azo-inulin gels was not observed. This may be attributed to a low partitioning of nicotinamide-adenine dinucleotide phosphate (NADP(+)) in the gels.
Algorithms↗
Ions and water in the epithelial cells of rabbit descending colon.
1. Isolated sheets of rabbit descending colon epithelial cells stripped from their underlying muscle coats were incubated in chambers at 37 degrees C with oxygenated media, and their non-inulin space water, sodium, potassium and chloride contents were subsequently determined. 2. With sodium Ringer bathing both surfaces, amiloride, 10(-4) M, decreased non-inulin space sodium content by 76 mmol/kg dry wt. Ouabain, 10(-3) M, caused loss of non-inulin space potassium which was not completely compensated for by uptake of sodium over 30 min incubation. Chloride and water, therefore, decreased. Amiloride, 10(-4) M, inhibited but did not prevent this uptake of sodium after ouabain. 3. Tissues exposed to sodium-free choline Ringer rapidly exchanged non-inulin space sodium for choline and, more slowly, lost potassium, chloride and water. The equilibration of sodium in the non-inulin space when sodium Ringer was restored to the mucosal medium alone was largely amiloride-insensitive. For restoration of non-inulin space potassium to normal levels, sodium was required in the serosal but not the mucosal medium. 4. Neither the absence of glucose nor the absence of chloride from the mucosal medium affected the non-inulin space sodium content when sodium was restored to the mucosal medium bathing sodium-depleted tissues. 5. It is argued that, whereas non-inulin space potassium and water contents are synonymous with their cellular values, only about one third of non-inulin space sodium is cellular when sodium Ringer bathes both surfaces, and the concentration of the sodium within the cellular transport pool approximated 20 mmol/kg H2O, consistent with estimates obtained from other techniques.
Amiloride↗
Evidence for a peritubular-to-luminal flux phosphate in the dog kidney.
The possible presence of a direct influx of phosphate into the tubular lumen of the dog kidney was examined by two different techniques. A 0.3-ml bolus of 32PO4 and [3H]inulin was injected into the renal artery of dogs with and without phosphate loading. The mean urinary transit time (TT) for PO4 was consistently less than the TT for inulin in nonphosphate-loaded dogs. Following phosphate loading the TT for phosphate approached but did not equal the TT for inulin. In contrast, after microinjections of 32PO4 and [3H]inulin into proximal tubules, the urinary TT of PO4 was significantly longer than the TT of inulin. The application of 32PO4 and [3H]inulin to the surface of the left kidney was associated with a greater recovery of 32PO4 from the left kidney compared to that from the right kidney. The recovery of [3H]inulin was proportional to the glomerular filtration rate for both kidneys. Application of the 32PO4 and [3H]inulin to the surface of a muscle resulted in an equal recovery of phosphate and inulin from both kidneys. The results demonstrate the presence of a detectable tubular influx of phosphate.
Animals↗
Brain-tumor chemotherapy. Pharmacological principles derived from a monkey brain-tumor model.
An implnated choriocarcinoma growing inthe brains of monkeys was used as a brain-tumor model for the study of the cerebral distribution of two commonly used physiological markers, inulin and albumin; tissue samples were obtained from the tumor, adjacent brain, and distant brain. An extravascular inulin space was calculated by subtracting the albumin (plasma) space from the total inulin spaces. The extravascular inulin space in the tumor was found to be 24%, a value significantly larger than that in distant brain (0.6%). The large inulin space of the tumor was probably the result of increases on both capillary permeability and the extracellular space within this area. Determination of the inulin space in 1 to 2-mm thick samples of tissue taken serially from the tumor center to the distant brain indicated a gradual decline in inulin concentration from the tumor's edge to distant brain. This distribution pattern could be the result of either a continuous decrease, running from the tumor to distant brain, in capillary permeability to inulin, or a diffusional flow of inulin from the tumor into the adjacent tissue. The failure of drugs to inhibit such a tumor in view of these observations is discussed.
Albumins↗
Urinary loss of glucose, phosphate, and protein by diffusion into proximal straight tubules injured by D-serine and maleic acid.
In several models of acute renal failure leakage of glomerular filtrate out of the tubule is an important pathogenetic mechanism; however, bidirectional diffusion of solute to account for certain pathophysiologic features of acute renal failure has received meager attention. Using micropuncture and clearance methods, we assessed sequentially leakage of solutes and inulin across proximal straight tubules (PST) injured by two nephrotoxins. In d-serine-treated rats with extensive necrosis of PST, the basis for glucosuria and tubular leakage of inulin was studied. Glucose absorption by the proximal convoluted tubule and glucose delivery to the PST were normal, but glucose delivery to the distal tubule was increased nearly 8-fold, indicating diffusion of glucose from interstitial to tubular luminal fluid across the necrotic PST. Total kidney inulin clearance was greatly reduced, but single nephron glomerular filtration rate, based on proximal convoluted tubule samples, was normal, indicating tubular loss of inulin. Urinary recovery of [14C]inulin infused into tubular lumina revealed that proximal convoluted tubule and distal tubule were impermeable to inulin and that inulin diffused out of the necrotic PST. The progressive return over 6 days of tubular impermeability for inulin correlated with relining of PST with new cells. In maleic acid-treated rats the site and extent of tubular necrosis and the nature of urinary loss of solutes were studied. Microdissection revealed that maleic acid caused limited necrosis of PST which averaged 7.4% of total proximal tubular length. Increased urinary excretion of protein, phosphate, and glucose and increased tubular permeability to microinfused [14C]inulin occurred with the onset of PST necrosis, and return of these abnormalities to normal correlated with the degree of cellular repair of the PST. Together these data indicate that with severe cellular injury there is bidirectional, concentration-dependent diffusion of solutes between the interstitial and tubular fluids. Thus, experimental or human toxic nephropathies should not be classified as acquired Fanconi's syndrome unless specific tubular transport defects are present.
Acute Kidney Injury↗