Effects of lung volume on clearance of solutes from the air spaces of lungs

1988 ◽  
Vol 64 (3) ◽  
pp. 1068-1075 ◽  
Author(s):  
B. T. Peterson ◽  
H. L. James ◽  
J. W. McLarty
Keyword(s):  
Human Serum Albumin ◽  
Lung Volume ◽  
Clearance Rate ◽  
Compartmental Analysis ◽  
Compartment Model ◽  
Lung Inflation ◽  
Experimental Animals ◽  
Two Compartment Model ◽  
Additional Control ◽  
Albumin Clearance

Several investigators have shown that the clearance rate of aerosolized 99mTc-labeled diethylenetriamine pentaacetate (DTPA, mol wt = 492, radius = 0.6 nm) from the air spaces of the lungs of humans and experimental animals increases with lung volume. To further investigate this phenomenon we performed a compartmental analysis of the 2-h clearance of DTPA from the lungs of anesthetized sheep using a new method to more accurately correct for the effects of DTPA recirculation. This analysis showed that the DTPA clearance in eight sheep ventilated with zero end-expired pressure was best described by a one-compartment model with a clearance rate of 0.42 ± 0.15%/min. Ventilating eight sheep with an end-expired pressure of 10 cmH2O throughout the study increased the end-expired volume 0.4 ± 0.1 liter BTPS and created a clearance curve that was best described by a two-compartment model. In these sheep 56 ± 16% of the DTPA cleared from the lungs at a rate of 7.9 ± 2.9%/min. The remainder cleared at a rate similar to that measured in the sheep ventilated with zero end-expired pressure (0.35 ± 0.18%/min). Additional control and lung inflation experiments were performed using 99mTc-labeled human serum albumin (mol wt = 66,000, radius = 3.6 nm). In six control sheep ventilated with zero end-expired pressure the albumin clearance was best described by a one-compartment model with a clearance rate of 0.06 ± 0.02%/min. The clearance rate in six sheep with increased lung volume was slightly larger (0.09 ± 0.02, P less than 0.05) but was well described by a one-compartment model.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship of end-expiratory pressure, lung volume, and 99mTc-DTPA clearance

1987 ◽  
Vol 63 (4) ◽  
pp. 1586-1590 ◽  
Author(s):  
J. A. Cooper ◽  
H. van der Zee ◽  
B. R. Line ◽  
A. B. Malik
Keyword(s):  
Lung Volume ◽  
Clearance Rate ◽  
Base Line ◽  
Lung Inflation ◽  
Alveolar Epithelial ◽  
Pulmonary Clearance ◽  
Residual Capacity ◽  
Dose Response Effect ◽  
Relationship Of ◽  
Line P

We investigated the dose-response effect of positive end-expiratory pressure (PEEP) and increased lung volume on the pulmonary clearance rate of aerosolized technetium-99m-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA). Clearance of lung radioactivity was expressed as percent decrease per minute. Base-line clearance was measured while anesthetized sheep (n = 20) were ventilated with 0 cmH2O end-expiratory pressure. Clearance was remeasured during ventilation at 2.5, 5, 10, 15, or 20 cmH2O PEEP. Further studies showed stepwise increases in functional residual capacity (FRC) (P less than 0.05) measured at 0, 2.5, 5, 10, 15, and 20 cmH2O PEEP. At 2.5 cmH2O PEEP, the clearance rate was not different from that at base line (P less than 0.05), although FRC was increased from base line. Clearance rate increased progressively with increasing PEEP at 5, 10, and 15 cmH2O (P less than 0.05). Between 15 and 20 cmH2O PEEP, clearance rate was again unchanged, despite an increase in FRC. The pulmonary clearance of aerosolized 99mTc-DTPA shows a sigmoidal response to increasing FRC and PEEP, having both threshold and maximal effects. This relationship is most consistent with the hypothesis that alveolar epithelial permeability is increased by lung inflation.

Phosphorus Fluxes in Limnetic Cladocerans: Coupling of Allometry and Compartmental Analysis

1994 ◽  
Vol 51 (5) ◽  
pp. 1055-1064 ◽  
Author(s):  
Yuan Hua Wen ◽  
Alain Vézina ◽  
Robert Henry Peters
Keyword(s):  
Body Weight ◽  
Steady State ◽  
Body Size ◽  
Time Course ◽  
Compartmental Analysis ◽  
Compartment Model ◽  
Size Dependent ◽  
Two Compartment Model ◽  
Metabolic Activities ◽  
Total P

A size-dependent two-compartment model was developed for estimation of 32P turnover and fluxes by limnetic cladocerans in steady state. After feeding on radioactively labelled food, uniformly labelled animals were fed unlabelled cells and the time course of release of tracer followed. Rates of turnover and size-specific fluxes were subsequently fitted to a two-compartment model. The model predicted that steady-state turnover and size-specific fluxes for 32P excretion declined with body weight and that the exponent of weight did not significantly differ from −0.25, suggesting the relationships between total P turnover or flux rates and body size in cladocerans follow the same allometry observed for other organisms and other metabolic activities. However, rate constants for intercompartmental exchanges declined faster than weight−0.25, indicating that their turnover and flux declined much faster with increasing body size than would be expected from general allometry. Size-specific ingestion and assimilation rates of 32P by cladocerans decreased with increasing body size with a slope of the allometric function similar to −0.25.

scholarly journals Erythropoietin kinetics in rats: generation and clearance

Blood ◽  
1986 ◽  
Vol 67 (3) ◽  
pp. 646-649 ◽  
Author(s):  
SE Steinberg ◽  
JF Garcia ◽  
GR Matzke ◽  
J Mladenovic
Keyword(s):  
Intravenous Injection ◽  
Plasma Volume ◽  
Rat Model ◽  
Clearance Rate ◽  
Half Life ◽  
Plasma Clearance ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Two Compartment Model ◽  
Disappearance Curve

Abstract Detailed studies to analyze the early events of erythropoietin (Ep) secretion and clearance were performed in a rat model using a double antibody radioimmunoassay. Ep clearance was determined following intravenous injection of 1 mL of Ep-rich plasma, 1,080 mU/mL, obtained from phlebotomized rats. Analysis revealed a disappearance curve that conformed to a two-compartment model with an alpha half-life t1/2 of 3.6 minutes and a beta t1/2 of 86 minutes. The volume of distribution was similar to the calculated plasma volume. In anephric animals, there was no change in the plasma clearance rate or the volume of distribution. Rapid Ep secretion was elicited by a single 15 mL/kg phlebotomy (hematocrit decrement 45% to 30%), so that levels reached 20 to 30 times baseline (524 +/- 76 v 24 +/- 7 mU/mL) at five hours, whereas they plateaued for at least 33 hours. The increase in the rate of secretion was geometric, from 9.9 mU/h baseline secretion to 429 mU/h. These data identify a very sensitive and rapidly responsive system for Ep modulation in the rat.

Pulmonary transvascular flux of transferrin

1989 ◽  
Vol 67 (5) ◽  
pp. 1850-1854 ◽  
Author(s):  
J. A. Cooper ◽  
A. B. Malik
Keyword(s):  
Plasma Concentration ◽  
Clearance Rate ◽  
Compartment Model ◽  
Input Function ◽  
Volume Of Distribution ◽  
Blood Pool ◽  
Two Compartment Model ◽  
Clearance Rate Constant ◽  
Extravascular Volume ◽  
Lung Lymph

We compared the pulmonary transvascular fluxes of transferrin and albumin in the intact sheep lung. Anesthetized sheep were prepared with lung lymph fistulas. The vascular blood pool was marked with 99mTc-erythrocytes, autologous transferrin was labeled with 113mIn, and albumin was labeled with 125I. Samples of blood, plasma, lymph, and lung were obtained up to 180 min after tracer infusion. Lymph tissue radioactivities were corrected for the intravascular component and expressed as extravascular-to-plasma concentration ratios. Clearance of transferrin and albumin from the plasma space followed a two-compartment model. The clearance rate constant was 2.1 +/- 0.1 x 10(-3) min for albumin and 2.4 +/- 0.1 x 10(-3) min for transferrin (P less than 0.05). Lymph-to-plasma ratios for albumin and transferrin were not different. However, the extravascular-to-plasma ratio for albumin was greater than transferrin (P less than 0.05). The lymph and lung data were deconvoluted for the plasma input function and fit to a two-compartment model. The results indicate that albumin and transferrin have similar permeabilities across the vascular barrier but have different pulmonary circulation to lymph kinetics because the extravascular volume of distribution of albumin is greater than transferrin.

Ozone inhibits phloem loading from a transport pool: compartmental efflux analysis in Pima cotton

2000 ◽  
Vol 27 (9) ◽  
pp. 859 ◽  
Author(s):  
David A. Grantz ◽  
John F. Farrar
Keyword(s):  
Sugar Content ◽  
Soluble Sugar ◽  
Carbon Assimilation ◽  
Compartmental Analysis ◽  
Compartment Model ◽  
Phloem Loading ◽  
Assimilate Transport ◽  
Future Research ◽  
Pima Cotton ◽  
Two Compartment Model

This paper originates from a presentation at the International Conference on Assimilate Transport and Partitioning, Newcastle, NSW, August 1999 The rate of export of recent photoassimilate from source leaves of Pima cotton (Gossypium barbadense L.) is inhibited by ozone (O3). To characterize these effects on export, source leaves of Pima cotton were exposed to pulses (0.75 h) of O3 (0.0, 0.2, 0.5 and 0.8 L L–1) followed by pulses of 14CO2. Leaves were monitored by gas exchange and with a Geiger–Muller tube, for a sufficient period to characterize carbon assimilation (A) and a rapid and a slower phase of export. Double exponential decay functions (two-compartment model) were fitted and a compartmental analysis conducted. O3 reduced by half the fast rate constant describing export from a transport pool, without affecting the rate constants for transport from or to a storage compartment. Measured soluble sugar contents increased slightly from control concentrations (1.2 g C m–2) by about 5–10% at all O3 concentrations. The calculated soluble sugar content in the transport pool increased from about 200 to 300 mg C m–2 with increasing exposure to O3. The calculated storage pool did not respond to O3 but exceeded measured contents. This discrepancy is attributed to starch deposition and mobilization, which are not considered in the two-compartment model, uncertainties in slower decay parameters, and non-steady-state A induced by O3 exposure. Specific inhibition of rapid efflux suggests oxidant damage at the plasmalemma or plasmodesmata of mesophyll or phloem companion cells, and little effect on the tonoplast. A was affected less than export. Future research should target oxidation of components involved in phloem loading.

The Mechanics of Terminal Lymph Flow

1985 ◽  
Vol 107 (4) ◽  
pp. 376-380 ◽  
Author(s):  
G. E. Miller ◽  
J. L. Seale
Keyword(s):  
Clearance Rate ◽  
Interstitial Fluid ◽  
Subcutaneous Tissue ◽  
Diffusion Constant ◽  
Compartment Model ◽  
External Pressure ◽  
Test Results ◽  
Sulfur Colloid ◽  
Two Compartment Model ◽  
External Pressures

The effects of external pressure on the terminal lymphatic clearance rate are studied. Sulfur colloid tagged with 99mTc is injected into the subcutaneous tissue in the hind thigh of canines. The activity of the tracer is measured over the injection site for 90 min to determine the lymphatic clearance rate of the sulfur colloid. Several experiments are performed at different external pressures applied to the surface of the canine thigh. A two-compartment model is defined to determine both the terminal lymphatic flow rate per unit volume of tissue and the diffusion constant (sulfur colloid/interstitial fluid) from the raw data. Experimental results indicate that increases in the external pressure applied to the skin cause terminal lymphatic clearance rates to increase until the pressure reaches 60 mm Hg. At this level, some test results showed reduced levels of clearance. At 75 mm Hg, the lymphatic clearance of sulfur colloid from the subcutaneous tissue was stopped suggesting occlusion of the vessels resulting from vessel collapse.

The Recovery of Terminal Lymph Flow Following Occlusion

1987 ◽  
Vol 109 (1) ◽  
pp. 48-54 ◽  
Author(s):  
G. E. Miller ◽  
J. L. Seale
Keyword(s):  
Clearance Rate ◽  
Subcutaneous Tissue ◽  
Applied Pressure ◽  
Compressive Loading ◽  
Compartment Model ◽  
External Pressure ◽  
Sulfur Colloid ◽  
Two Compartment Model ◽  
External Pressures ◽  
Pressure Phase

The effects of external pressure on the relative terminal lymphatic flow rate following occlusion of the lumph system were studied. Sulfur colloid tagged with 99mTc was injected into the hind thigh of dogs prior to compressive loading. Initially, the lymphatic clearance of the tracer was measured for approximately forty minutes with no applied external pressure. The terminal lymph vessels were then occluded for thirty minutes with the application of an applied external pressure of 75 mm Hg. Finally, the lymphatic clearance following occlusion was measured with the application of a nonocclusive pressure. External pressures of 0, 30, and 45 mm Hg were tested to determine the effects of post-occlusive pressure application on terminal lymphatic clearance. Results indicated that terminal lymphatic clearance did not resume for an applied pressure of 45 mm Hg following occlusion. The relative lymphatic clearance rate at an external pressure of 30 mm Hg following occlusion was 54% of the clearance rate for a 0 mm Hg applied pressure prior to lymph occlusion. The results for a 0 mm Hg external pressure following occlusion indicated a 23 percent clearance rate compared to the pre-occlusive state. A two compartment model was utilized to determine the lymphatic clearance rate per unit tissue volume of subcutaneous tissue from the experimental data for each pressure phase.

scholarly journals Erythropoietin kinetics in rats: generation and clearance

Blood ◽  
1986 ◽  
Vol 67 (3) ◽  
pp. 646-649
Author(s):  
SE Steinberg ◽  
JF Garcia ◽  
GR Matzke ◽  
J Mladenovic
Keyword(s):  
Intravenous Injection ◽  
Plasma Volume ◽  
Rat Model ◽  
Clearance Rate ◽  
Half Life ◽  
Plasma Clearance ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Two Compartment Model ◽  
Disappearance Curve

Detailed studies to analyze the early events of erythropoietin (Ep) secretion and clearance were performed in a rat model using a double antibody radioimmunoassay. Ep clearance was determined following intravenous injection of 1 mL of Ep-rich plasma, 1,080 mU/mL, obtained from phlebotomized rats. Analysis revealed a disappearance curve that conformed to a two-compartment model with an alpha half-life t1/2 of 3.6 minutes and a beta t1/2 of 86 minutes. The volume of distribution was similar to the calculated plasma volume. In anephric animals, there was no change in the plasma clearance rate or the volume of distribution. Rapid Ep secretion was elicited by a single 15 mL/kg phlebotomy (hematocrit decrement 45% to 30%), so that levels reached 20 to 30 times baseline (524 +/- 76 v 24 +/- 7 mU/mL) at five hours, whereas they plateaued for at least 33 hours. The increase in the rate of secretion was geometric, from 9.9 mU/h baseline secretion to 429 mU/h. These data identify a very sensitive and rapidly responsive system for Ep modulation in the rat.

Surfactant disaturated phosphatidylcholine kinetics in infants with bronchopulmonary dysplasia measured with stable isotopes and a two-compartment model

2005 ◽  
Vol 99 (1) ◽  
pp. 323-329 ◽  
Author(s):  
Paola E. Cogo ◽  
Gianna Maria Toffolo ◽  
Antonina Gucciardi ◽  
Arianna Benetazzo ◽  
Claudio Cobelli ◽  
...  
Keyword(s):  
Bronchopulmonary Dysplasia ◽  
Gestational Age ◽  
Decay Curve ◽  
Compartmental Analysis ◽  
Compartment Model ◽  
Study Groups ◽  
Gas Chromatography Mass Spectrometry ◽  
Isotope Tracer ◽  
Two Compartment Model ◽  
Intracellular Storage

We previously found a shorter surfactant disaturated phosphatidylcholine palmitate (DSPC-PA) half-life in infants with bronchopulmonary dysplasia (BPD) by using a single stable isotope tracer and simple formulas based on a one-exponential fit of the final portion of the enrichment decay curve. The aim of this study was to apply noncompartmental and compartmental analysis on the entire enrichment decay curve of DSPC-PA and to compare the kinetic data with our previous results. We analyzed 10 preterm newborns with BPD (gestational age 26 ± 0.6 wk, weight 777 ± 199 g) and 6 controls (gestational age 26 ± 1.4 wk, weight 787 ± 259 g). All took part in our previous study. Endotracheal 13C-labeled dipalmitoyl phosphatidylcholine was administered, and the 13C-enrichment of surfactant DSPC-PA was measured from serial tracheal aspirates by gas chromatography-mass spectrometry. Noncompartmental and compartmental models were numerically identified from the tracer-to-tracee ratio and kinetic parameters related to the accessible (pool accessible to sampling, likely to be the lung alveolar pool) and to the nonaccessible pools (pools not accessible to samplings, likely to be the intracellular storage pool) were estimated in the two study groups. Comparison was performed by Mann-Whitney test. A two-compartment model provided the most reliable assessment of DSPC-PA kinetics. In BPD vs. controls, mean ± SE residence time of DSPC-PA in the accessible was 17.5 ± 2.6 vs. 32.2 ± 6.4 h ( P < 0.05), whereas it was 49.7 ± 3.5 vs. 54.4 ± 3.9 h (NS, not significant) in the nonaccessible pool; DSPC-PA recycling was 0.26 ± 0.05 vs. 0.43 ± 0.04% (NS), respectively. A two-compartment model of surfactant DSPC-PA kinetics allowed a thorough assessment of DSPC-PA kinetics, including masses, synthesis, and fluxes between pools. The most important findings of this study are that in BPD infants DSPC-PA loss from the alveolar pool was higher and recycling through the intracellular pool lower than in controls.

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