Distribution of Blood Flow in the Digestive Tract of the Rat

Steiner, Sheldon H.; Mueller, Gustave C. E.

doi:10.1161/01.res.9.1.99

Cited by 50 publications

(13 citation statements)

References 23 publications

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“…Our findings in the stomach and intestine are similar to what has been reported in other species (Dinda and Beck 1986;Steiner and Mueller 1961;Goodhead 1969). In the small intestine, a distally decreasing gradient in total wall intestinal bTood flow was present.…”

Section: Absolute G B~d Flow Of the Stomach And The Intestinesupporting

confidence: 92%

Gastrointestinal blood flow in the opossum with special reference to the esophagus

Zijlstra¹,

Hynna-Liepert²,

Dinda³

et al. 1990

Can. J. Physiol. Pharmacol.

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The opossum esophagus, like that of the human, is composed of striated muscle fibres proximally and smooth muscle fibres distally. Because of this similarity the opossum has been used extensively as an animal model for esophageal studies, but to date no data on esophageal blood flow have been reported in this species. The purpose of this study was to establish the basal blood flow characteristics of different regions of the opossum gastrointestinal tract with particular reference to the esophagus. Intracardiac injection of 15-microns microspheres was used to provide an estimate of blood flow (mL.min-1.g-1 dry tissue) to the whole wall, the combined layer of mucosa plus submucosa, and the muscularis propria. Basal blood flow in the whole tissue and mucosa-submucosa was significantly higher in the lower esophageal sphincter than in the proximal or distal esophagus. The muscularis propria blood flow displayed an aborally increasing gradient with flow to proximal esophagus (striated muscle) less than distal esophagus (smooth muscle) less than lower esophageal sphincter. Regional differences in blood flow to other regions of the gastrointestinal tract were similar to that described in other species. In addition, no changes in basal blood flow occurred despite repeated microsphere injections, suggesting that this species provides a good animal model for the study of gastrointestinal blood flow.

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Section: Absolute G B~d Flow Of the Stomach And The Intestinesupporting

confidence: 92%

Gastrointestinal blood flow in the opossum with special reference to the esophagus

Zijlstra¹,

Hynna-Liepert²,

Dinda³

et al. 1990

Can. J. Physiol. Pharmacol.

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“…Exponential fitting of the data of Inclusion of results from additional animals gave a mean value of 61 ± 17 (mean ± SD) ml/100 g per min (n = 5). This compares favorably with Steiner's determination of HBF in the fasted Sprague-Dawley rat, HBF = 80+ ml/100 g per min (n = 17) (26).…”

supporting

confidence: 66%

Deuterium nuclear magnetic resonance measurements of blood flow and tissue perfusion employing 2H2O as a freely diffusible tracer.

Ackerman¹,

Ewy²,

Becker³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

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The use of deuterium oxide (21120) is proposed as a freely diffusible nuclear magnetic resonance (NMR) blood flow and tissue perfusion tracer of potential clinical utility. Deuterium is a stable, nonradiative isotope commercially available as 2H20 at enrichment levels of essentially 100%-i.e., 110 molar equivalent deuterium. This high concentration, together with the short relaxation time of the spin 1 (quadrupole) deuterium nuclide, provides substantial sensitivity for NMR spectroscopy. As a result, when 2H20 is administered in a bolus fashion to a specific tissue or organ in vivo, the deuterium NMR intensity time course can be analyzed, using mathematical models developed by others for radiolabeled tracers, to measure the rate of blood flow and tissue perfusion. Such an application is demonstrated herein at a static magnetic field of 8.5 tesla. Using single-compartment flow modeling, hepatic blood flow and tissue perfusion in fasted (18 hr) male Sprague-Dawley rats was determined to be 61 ± 17 (mean ± SD) ml/100 g per min (n = 5).The measurement of regional blood flow and tissue perfusion provides an important clinical indicator of tissue viability and vascular competency. Nuclear magnetic resonance (NMR) flow measurement techniques, including those based on spin-imaging procedures, that employ observation of the naturally abundant 1H resonance from H20 have been developed (for reviews, see refs. 1-3). These techniques generally rely on the spatial evolution of 1H magnetization after the initial preparation of a nonequilibrium spin-state population distribution. Therefore, magnetic resonance flow measurements are often limited by the lifetime of the nonequilibrium state and, thus, by the water spin-lattice and spin-spin 1H relaxation times. However, such approaches are extremely attractive because of their completely noninvasive nature and their development remains an area of very active investigation (4, 5).Alternatively, as described in the early pioneering work of Kety (6-8), one can introduce an exogenous substance as a blood-flow tracer, usually one containing a radiolabel. Although the administration of the tracer substance introduces an invasive character to the flow measurement, the high sensitivity of nuclear decay detection and the use of radiolabels that decay slowly relative to blood flow result in measurement methods of considerable practical utility (9-11). Importantly, by employing tracer substances that freely diffuse through aqueous spaces (i.e., intracellular, interstitial), a quantification of tissue perfusion is achieved in contrast to a measurement of simply linear or plug flow velocity in large vessels. One such tracer substance that has seen considerable use in combination with positron emission detection is H2150 (12)(13)(14)(15)(16)(17)(18).We propose herein the analogous use of 2H20 as a diffusible blood-flow and tissue-perfusion tracer where deuterium NMR is used to monitor label intensity as a function of time. Deuterium is a nonradiative, naturally abundant (0.0156%), quadr...

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“…Even a highly lipid-soluble gas, such as '3Xe, has a A of 0.74 (2). Hepatic blood flow in the rat is about 1.9 ml/g/min (3). It can be calculated, therefore, that within 3 min the partial pressure of the gases in liver tissue will have reached 95 % of their final equilibrated concentrations.…”

Section: Experimental Designmentioning

confidence: 99%

“…Inspection of the data for the diffusion-limited model II '/°CH4 FIGURE 3 Relation of the absorption rate of gases to their solubilities in blood (model I). The observed absorption rate of a gas relative to CH4(Q./QCH4) is plotted against the ratio of the solubility of the gas in blood to that of CH4(ao/acH4).…”

Section: Lich4pch4mentioning

confidence: 99%

Use of Inert Gases to Study the Interaction of Blood Flow and Diffusion during Passive Absorption from the Gastrointestinal Tract of the Rat

Levitt

Levitt²

1973

J. Clin. Invest.

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A B S T R A C T Measurement of the relative absorption rates of inert gases (H2, He, CH4, SF6, and n33Xe) was used to investigate the interaction between diffusion and blood flow during passive absorption from the stomach, small bowel, and colon of the rat. If uptake is blood flow limited, the gases should be absorbed in proportion to their solubilities in blood, but if diffusion limited, uptake should be proportional to the diffusion rate of the gases in mucosal tissues.The observed absorption data were fitted to a series of models of interaction between perfusion and diffusion. A simple model accurately predicted the absorption rates of the gases from all segments of bowel. In this model, gas is absorbed into two distinct blood flows: one which flows in proximity to the lumen and completely equilibrates with the lumen, and a second which is sufficiently rapid and distant from the lumen that its gas uptake is entirely diffusion limited. The fraction of the total absorption attributable to the equilibrating flow can be readily calculated and equalled 93%, 77%, and 33% for the small bowel, colon, and stomach, respectively. Thus the rate of passive absorption of gases from the small bowel is limited almost entirely by the blood flow to the mucosa, and absorption from the stomach is largely limited by the diffusion rate of the gases. The flow which equilibrates with the lumen can be quantitated, and this flow may provide a useful measure of "effective" mucosal blood flow.

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Distribution of Blood Flow in the Digestive Tract of the Rat

Cited by 50 publications

References 23 publications

Gastrointestinal blood flow in the opossum with special reference to the esophagus

Gastrointestinal blood flow in the opossum with special reference to the esophagus

Deuterium nuclear magnetic resonance measurements of blood flow and tissue perfusion employing 2H2O as a freely diffusible tracer.

Use of Inert Gases to Study the Interaction of Blood Flow and Diffusion during Passive Absorption from the Gastrointestinal Tract of the Rat

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