Kinetics of zinc absorption by the rat jejunum: effects of adrenalectomy and dexamethasone

1983 ◽  
Vol 244 (3) ◽  
pp. G314-G320 ◽  
Author(s):  
R. F. Bonewitz ◽  
E. C. Foulkes ◽  
E. J. O'Flaherty ◽  
V. S. Hertzberg
Keyword(s):  
Compartment Model ◽  
The Body ◽  
Adult Rat ◽  
Two Compartment Model ◽  
65Zn Uptake ◽  
Mathematical Simulations ◽  
Adrenocortical Hormone ◽  
Perfusion Period ◽  
Kinetics Of

Effects of dexamethasone and adrenalectomy on the kinetics of jejunal 65Zn uptake and absorption were studied in the anesthetized adult rat. The jejunal lumen was perfused in situ with 5 mM glucose in 150 mM saline containing 65Zn and [14C]polyethylene glycol as volume marker. Over the 30-min perfusion period, the rate of net 65Zn removal from the perfusate was biexponential due to the establishment of a return flux to the lumen. An open two-compartment model satisfactorily describes these observations: (formula; see text) Dexamethasone (2 mg/kg ip 7 h before perfusion) increased k12 by 75% (P less than 0.0002) and decreased k20 by 45% (P less than 0.04). Both effects were independent of adrenalectomy. Mathematical simulations using the compartmental model and experimentally determined kinetic constants predicted that transfer of 65Zn into the body should be enhanced by adrenalectomy and retarded by dexamethasone administered to adrenalectomized rats. Dexamethasone and adrenalectomy thus differentially affect Zn uptake and absorption in this system, suggesting a possible adrenocortical hormone involvement in the regulation of Zn absorption. These changes are apparently not mediated via metallothionein.

scholarly journals A comparison of the short-term kinetics of zinc metabolism in women during fasting and following a breakfast meal

1998 ◽  
Vol 80 (4) ◽  
pp. 363-370 ◽  
Author(s):  
Nicola M. Lowe ◽  
Leslie R. Woodhouse ◽  
Janet C. King
Keyword(s):  
Energy Content ◽  
Compartment Model ◽  
Zinc Metabolism ◽  
Short Term ◽  
Compartment System ◽  
Breakfast Meal ◽  
Physiological Importance ◽  
Two Compartment Model ◽  
Zn Concentration ◽  
Kinetics Of

The physiological importance and mechanism of the postprandial fall in plasma Zn concentration is not well understood. In order to gain further information on this apparent redistribution of plasma Zn, a stable isotope, 70Zn, was used to study the effect of a breakfast meal on plasma Zn kinetics. Nine women participated in two trials, a fasting trial and a breakfast-meal trial; five of the women participated in a third trial in which the energy content of the breakfast meal was doubled. At each trial, 0.1mg of 70Zn was infused intravenously, and the plasma disappearance of the isotope was analysed using a two-compartment model of Zn kinetics. Plasma Zn concentration fell significantly following the two trials in which the subjects were given meals, reaching low points that were 13 and 19 %, respectively, below concentrations at comparable times during the fasting trial. Kinetic analysis revealed that after the doubled breakfast meal there was a significant fall (P < 0.007) in the size of the most rapidly turning over Zn pool (pool (a)) from 2.90 (se 0.13)mg in the fasting state to 2.47 (se 0.14) mg postprandially. The fractional turnover rate of pool (a) to other extravascular Zn pools, i.e. outside the two-compartment system, was also significantly elevated after the doubled breakfast meal (P < 0.05). These results suggest that the decline in plasma Zn concentration following a meal is due to a redistribution of Zn from the plasma to other more slowly turning over extravascular pools that may be involved in the assimilation and metabolism of fuels following food intake.

Kinetics of transepithelial movement of heavy metals in rat jejunum

1987 ◽  
Vol 253 (2) ◽  
pp. G134-G138
Author(s):  
E. C. Foulkes ◽  
D. M. McMullen
Keyword(s):  
Heavy Metals ◽  
Venous Blood ◽  
Compartment Model ◽  
Intestinal Lumen ◽  
Rat Jejunum ◽  
Temperature Dependent ◽  
Appearance Time ◽  
Portal Venous Blood ◽  
Kinetics Of

The kinetics of the transepithelial movement of heavy metals were studied in the perfused rat jejunum in situ. The peak appearance time (TET) of Zn, Ni, and Cd in portal venous blood was determined after their transient (10 s) introduction into the intestinal lumen. Observed TET values for these metals were positively correlated with their affinities for metallothionein and agreed with those predicted on the basis of a linear three-compartment model that does not allow for paracellular pathways. Further evidence was provided to support the hypothesis that Cd absorption consists first of Cd binding to negative membrane charges followed by a temperature-dependent internalization step.

Mathematical Modeling of Different Molecule Removal on On-Line Haemodiafiltration: Influence of Dialysis Duration and Infusion Flow

2015 ◽  
Vol 39 (4) ◽  
pp. 288-296 ◽  
Author(s):  
Francisco Maduell ◽  
Juan Sanchez ◽  
Marta Net ◽  
Miquel Gomez ◽  
Jose M. Gonzalez ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Treatment Time ◽  
Compartment Model ◽  
Dialysis Dose ◽  
Β2 Microglobulin ◽  
Dialysis Duration ◽  
Two Compartment Model ◽  
On Line ◽  
The Impact ◽  
Kinetics Of

Background: In a previous study on a nocturnal, every-other-day online haemodiafiltration scheme, different removal patterns were observed for urea, creatinine, β2-​microglobulin, myoglobin and prolactin. The aim of this study was to evaluate the influence of dialysis duration and infusion flow (Qi) on the removal of different molecular weight (MW) solutes, and to quantify the effect of the different treatments on the kinetics of the solutes by using a classical two-compartment model. Methods: This prospective, in-center study was carried out in 10 patients on a nocturnal, every-other-day online post-dilution haemodiafiltration program. Each patient received four dialysis sessions with different conditions, two 4-h sessions (with infusion flows of 50 or 100 ml/min) and two 8-h sessions (with infusion flows of 50 or 100 ml/min). To analyze the solute kinetics, blood samples were obtained hourly during the dialysis treatments and in the first 3 h post-dialysis. Results: Removal patterns differed in the molecules studied, which were quantified by means of the two-compartment mathematical model. The main results show the impact of dialysis duration on the removal of low molecular weight molecules (urea and creatinine), while the impact of Qi is clearly shown for high molecular weight molecules (myoglobin and prolactin). For middle molecular weight solutes, such as β2-microglobulin, both factors (duration and Qi) enhance the removal efficiency of the dialyzer. Conclusions: Our study evaluates experimentally and mathematically how treatment time and infusion flow affect the filtration of solutes of different MW during post-dilution haemodiafiltration. The results provided by the present study should help physicians to select and individualise the most appropriate schedules to deliver an optimum diffusive and convective dialysis dose for each patient.

Influence or age and sex on the kinetics of intravenously administered L-phenylalanine.

1982 ◽  
Vol 28 (1) ◽  
pp. 204-206 ◽  
Author(s):  
R Jagenburg ◽  
C G Regårdh ◽  
S Rödjer
Keyword(s):  
Total Body Clearance ◽  
Kinetic Studies ◽  
Compartment Model ◽  
Peripheral Compartment ◽  
Two Compartment Model ◽  
Total Body ◽  
Kinetics Of ◽  
Effect Of Age ◽  
Age And Sex ◽  
Body Clearance

Abstract We studied the kinetics of intravenously administered L-phenylalanine with respect to the effect of age and sex, using a two-compartment model. We found that the volume of the peripheral compartment and total body clearance decrease with age. The sex-related influence was less obvious when distribution volumes and total body clearance were corrected for differences in body size. We emphasize the necessity of having age-matched control subjects in kinetic studies.

A Physiologically Based, Recirculatory Model of the Kinetics and Dynamics of Propofol in Man

2005 ◽  
Vol 103 (2) ◽  
pp. 344-352 ◽  
Author(s):  
Richard N. Upton ◽  
Guy Ludbrook
Keyword(s):  
Management Strategies ◽  
Compartment Model ◽  
The Body ◽  
Data Sets ◽  
Blood Flows ◽  
Two Compartment Model ◽  
Physiologically Based ◽  
Kinetics And Dynamics ◽  
In Series ◽  
Recirculatory Model

Background The disposition of propofol in man is commonly described using a three-compartment mamillary model. However, these models do not incorporate blood flows as parameters. This complicates the representation of the changes in blood flows that may occur in surgical patients. In contrast, complex physiologically based models are derived from data sets (e.g., tissue:blood partition coefficients) that may not be readily collected in man. Methods Alternatively, the authors report a recirculatory model of propofol disposition in a "standard" man that incorporates detailed descriptions of the lungs and brain, but with a lumped description of the remainder of the body. The model was parameterized from data in the literature using a "meta-modeling" approach. The first-pass passage of propofol through the venous vasculature and the lungs was a function of the injected drug mixing with cardiac output and passing through a three-"tank in series" model for the lungs. The brain was represented as a two-compartment model defined by cerebral blood flow and a permeability term. The Bispectral Index was a linear function of the mean brain concentration. The remainder of the body was represented by compartment systems for the liver, fast distribution and slow distribution. Results The model was a good fit of the data and was able to predict other data not used in the development of the model. Conclusions The model may ultimately find a role in improving the fidelity of patient simulators currently used to train anesthetists and for clinical practice simulation to optimize dosing and management strategies.

scholarly journals Vitamin E kinetics in sheep

1987 ◽  
Vol 58 (1) ◽  
pp. 113-125 ◽  
Author(s):  
M. Hidiroglou ◽  
K. Karpinski
Keyword(s):  
Vitamin E ◽  
Jugular Vein ◽  
Compartment Model ◽  
The Other ◽  
Intravenous Route ◽  
Biological Availability ◽  
Blood Samples ◽  
Two Compartment Model ◽  
Three Compartment Model ◽  
Kinetics Of

1. Kinetics of physiological doses of D-α-[5-Me-3H]tocopherol(200 μCi) administered to twenty-four sheep were studied using one of four routes: intravenous, oral (capsules), intraruminal and intramuscular.2. Blood samples were withdrawn from the jugular vein periodically for 96 h after the intravenous and oral administrations, for 168 h after the intraruminal administration and for 216 h after the intramuscular administration.3. The study indicated that the biological availability of α-tocopherol followed the order intravenous > intramuscular > oral > intraruminal.4. The rate of elimination was in the order intravenous > oral > intraruminal ˜ intramuscular.5. The intravenous route was fitted with a three-compartment model, whereas the other routes exhibited a good fit for either a one- or two-compartment model.

scholarly journals Quantification of Volumetric Bone Mineral Density of Proximal Femurs Using a Two-Compartment Model and Computed Tomography Images

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Yan-Lin Liu ◽  
Jui-Ting Hsu ◽  
Tian-Yu Shih ◽  
Dmytro Luzhbin ◽  
Chun-Yuan Tu ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Bone Mineral Density ◽  
Bone Mineral ◽  
Compartment Model ◽  
The Body ◽  
Volumetric Bone Mineral Density ◽  
Mineral Density ◽  
The Real ◽  
Computed Tomography Images ◽  
Two Compartment Model

Objectives. Dual-energy X-ray absorptiometry (DXA) is frequently used to measure the areal bone mineral density (aBMD) in clinical practice. However, DXA measurements are affected by the bone thickness and the body size and are unable to indicate nonosseous areas within the trabecular bone. This study aims to quantify the volumetric bone mineral density (vBMD) using computed tomography (CT) images and the two-compartment model (TCM) methods. Methods. The TCM method was proposed and validated by dipotassium phosphate (K2HPO4) phantoms and a standard forearm phantom. 28 cases with DXA scans and pelvic CT scans acquired within six months were retrospectively collected. The vBMD calculated by TCM was compared with the aBMD obtained from DXA. Results. For the K2HPO4 phantoms with vBMD ranging from 0.135 to 0.467 g/cm3, the average difference between the real and calculated vBMD was 0.009 g/cm3 and the maximum difference was 0.019 g/cm3. For the standard forearm phantom with vBMD of 0.194, 0.103, and 0.054 g/cm3, the average differences between the real and calculated vBMD were 0.017, 0.014, and 0.011 g/cm3. In the clinical CT image validation, a good linear relationship between vBMD and aBMD was observed with the Pearson correlation coefficient of 0.920 (p<0.01). Conclusions. The proposed TCM method in combination with the homemade cortical bone equivalent phantom provides accurate quantification and spatial distribution of bone mineral content.

scholarly journals Models for in vivo Kinetic Interactions of Dopamine D2-Neuroreceptors and 3-(2'-[18F]Fluoroethyl)Spiperone Examined with Positron Emission Tomography

1989 ◽  
Vol 9 (6) ◽  
pp. 840-849 ◽  
Author(s):  
Mark M. Bahn ◽  
Sung-Cheng Huang ◽  
Randall A. Hawkins ◽  
Nagichettiar Satyamurthy ◽  
John M. Hoffman ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Nonlinear Model ◽  
Compartment Model ◽  
Emission Tomography ◽  
Positron Emission ◽  
Two Compartment Model ◽  
Model Configuration ◽  
Net Uptake ◽  
Kinetics Of

The in vivo tracer kinetics of 3-(2apos;-[18F]fluoroethyl)spiperone (FESP) in the caudate/striatum and cerebellar regions of the human and monkey brain were studied with positron emission tomography (PET). The minimal model configuration that can describe the kinetics was determined statistically. Three two-compartment model configurations were found to be suitable for describing the kinetics in caudate/striatum and cerebellum: (1) a nonlinear model (five parameters) applicable to studies using nontracer (partially saturating) quantities of FESP in monkey striatum, (2) a linear four-parameter model applicable to the caudate/striatal and cerebellar kinetics in human and monkey studies with tracer quantities of FESP, and (3) a linear three-parameter model derived from the four-parameter model by assuming irreversible binding applicable to tracer studies of the human caudate. In the human studies, when the caudate kinetics ( n = 4) were fit by model 2 (with four parameters), the value of the in vivo ligand dissociation constant kd was found to be 0.0015 ± 0.0032/min. The three-parameter model (model 3) was found to fit the data equally well; this model is equivalent to model 2 with kd set to zero. In the monkey studies, it was found that for short (90 min) studies using tracer quantities of FESP, model 2 fit the striatal kinetics better than model 3. The parameters estimated using model 2 (four parameters) were in better agreement with those estimated by the nonlinear model (model 1) than those estimated using model 3 (three parameters). The use of a graphical approach gives estimates of the plasma–tissue fractional transport rate constant K1 and the net uptake constant K3 comparable to estimates using model 3 for both human and monkey studies.

Pharmacokinetic studies on Sulfamonomethoxine in rabbits

2019 ◽  
Vol 20 (2) ◽  
pp. 92-97
Author(s):  
M Amer ◽  
M Elsayed ◽  
S Kazawaki ◽  
W Fathy ◽  
Eman El-Ashry
Keyword(s):  
Half Life ◽  
Area Under The Curve ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
The Body ◽  
Pharmacokinetic Studies ◽  
Plasma Drug ◽  
Time Data ◽  
Drug Concentrations ◽  
Two Compartment Model

The present study was performed to determine the pharmacokinetics of sulfamonomethoxine (20mg/kg) in 5 rabbits after its oral and intravenous administration. Blood samples were collected immediately before (time 0) and at 0.08, 0.25, 0.5, 1, 3, 5 and 8 hours post-dosing to evaluate the pharmacokinetics of sulfamonomethoxine. Plasma sulfamonomethoxine concentrations were quantified with HPLC-UV, and plasma drug concentration versus time data after IV was best fitted to the two-compartment model, characterized with the distribution phase (α) equaled to 2.05 h-1 with a distribution half-life [t0.5(α)] equaled to 0.61 h. The volume of distribution of (V1c) was 0.15 ml/kg., whereas the volume of distribution at a steady – state [Vdss] was 0.20 ml/kg, and the body clearance was 0.03 ml/ kg / h. After oral administration of SMM, plasma drug concentrations were best fitted to a two-compartment model, of which the mean half-life of absorption (t1/2ab) and elimination (t1/2β) were 0.02 and 1.99 h, respectively. The maximal absorption concentration (Cmax) was estimated as 114.06 µg/ml at 0.12 h, and the Area under the curve (AUC) was 340.42 µg/ml/h.

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