An optical multiple indicator dilution technique to measure lung permeability-surface area: calibration and baseline measurement

Diffusion and viscosity-dependent flow rates generally decrease with decrease of temperature in biological systems. We have examined the extraction (Ec) of tracer water in isolated dog lungs perfused near 37 degrees C and near 15 degrees C with multiple-indicator dilution experiments. If Ec were barrier limited, Ec should be less at lower temperatures. Two runs at 37 degrees C were followed by two runs at 15 degrees C. Evans blue (T-1824) was used as vascular reference, and tritium oxide (THO) was used as water tracer. Values of Ec were based on the ratio of the areas under the two indicator curves from appearance time to time of peak of T-1824. Values for permeability-surface area (PS) products were calculated from the classical Crone relationship in 14 experiments with a total of 56 runs. Neither Ec nor PS decreased with temperature. Instead, modest but statistically significant increases were found. We conclude that the extraction of tracer water in these preparations is not barrier limited.

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Assessment of Liver Microcirculation with the Multiple Indicator Dilution Technique

Liver Microcirculation and Hepatobiliary Function - Progress in Applied Microcirculation ◽

10.1159/000422310 ◽

2015 ◽

pp. 40-51 ◽

Cited By ~ 1

Author(s):

J. Reichen

Keyword(s):

Indicator Dilution ◽

Dilution Technique ◽

Liver Microcirculation ◽

Multiple Indicator Dilution ◽

Indicator Dilution Technique ◽

Multiple Indicator

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A comparison of ascorbate and glucose transport in the heart

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1985.249.1.h141 ◽

1985 ◽

Vol 249 (1) ◽

pp. H141-H149 ◽

Cited By ~ 2

Author(s):

J. B. Bassingthwaighte ◽

J. T. Kuikka ◽

I. S. Chan ◽

T. Arts ◽

R. S. Reneman

Keyword(s):

Surface Area ◽

Indicator Dilution ◽

Cell Permeability ◽

Intracellular Space ◽

Molecular Weights ◽

Multiple Indicator Dilution ◽

Modeling Analysis ◽

Permeability Surface ◽

Spatially Distributed ◽

Multiple Indicator

Multiple indicator-dilution experiments were done to compare the transcapillary exchange of tracer amounts of L-[14C]ascorbate and D-[3H]glucose (against an intravascular reference 131I-albumin) in Ringer-perfused (5 mM glucose) isolated rabbit hearts. The indicator-dilution curves for the two were virtually superimposed over the first 40-80 s. Estimates of the capillary permeability-surface area products, PSc, were the same, 2.3 +/- 0.7 (SD) ml X g-1 X min-1 (n = 18), in accord with the coincidence of their instantaneous extractions. The similarity of glucose and ascorbate permeabilities is explained by the similarity in molecular weights and passive diffusivity, their lipophobic nature, and the paucity of carrier-mediated endothelial transport for either molecule. The data were analyzed via a model composed of aggregates of spatially distributed capillary-tissue units (capillary blood, interstitium, myocytes) accounting for the heterogeneity of regional flows. The interstitial volumes in this preparation are enlarged, 0.30 +/- 0.04 ml/g. There is substantial entry into myocardial cells, the cell permeability-surface area products being approximately 2-3 ml X g-1 X min-1 for ascorbate and glucose. The estimated volumes of interstitial and intracellular space, 0.30 and 0.47 ml X g-1 X min-1, reflect interstitial edema and are very close to measured values, giving reassurance concerning the methods of modeling analysis.

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