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Dive into the research topics where Aubrey E. Taylor is active.

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Featured researches published by Aubrey E. Taylor.


Circulation Research | 1965

Permeability of the Alveolar Membrane to Solutes

Aubrey E. Taylor; Arthur C. Guyton; Vernon S. Bishop

The lower lobe of the left lung of 54 dogs was isolated and perfused with a dextran-Tyrodes solution. The alveoli were filled with Tyrodes solution, and permeability coefficients were measured for diffusion of several substances across the alveolar membrane. The permeability coefficients of the pulmonary membrane for K42, urea, Na24, glucose, D2O, and dinitrophenal(DNP) were 56.5 ± 3.5, 22.9±9.2, 7.5±2.1, 3.1±0.7, 400, and 400×10−7 cm/sec, respectively. The effect of varying the flow rate on the permeability coefficient of Na24 was investigated, and the data failed to show any significant correlation between the flow limits of 3.8 to 12. 8 cm/min/g lung tissue. The effect of two different procedures for filling the alveoli with fluid on the permeability coefficients was also investigated and no difference could be discerned in the results. The data support the thesis that the alveolar membrane has permeability characteristics similar to those of the usual cell membrane. The interstitial fluid volume of the lung (extravascular sodium space) was measured and yielded a value in normal lungs of 0.250 ± 0.129 cc/g lung tissiue. In three edematous lungs, this space averaged three times the normal value.


Circulation Research | 1981

Vascular permeability and transvascular fluid and protein transport in the dog lung.

J C Parker; R E Parker; D N Granger; Aubrey E. Taylor

We used steady state lymph-to-plasma concentration ratios of six endogenous protein fractions (effective hydrodynamic radii of 37,40,44, 53,100, and 120 A) to estimate pulmonary capillary permeability characteristics. Pulmonary lymph was collected from an afferent lymphatic to the left tracheobronchial lymph node, and left atrial pressure was elevated in steps until the lymphatic protein concentration obtained a constant value. Lymph flow and transvascular protein flux increased with each increase in left atrial pressure. Convective flux was the predominant mode of transport for the smaller fractions, and solvent-drag reflection coefficients increased as lymph flow increased. This dependency on lymph flow (capillary filtration) indicates a heteroporous membrane system. For lymph flows greater than five times control, the solvent-drag reflection coefficients were: 0.59 ± 0.11, 0.52 ± 0.06, 0.66 ± 0.05, 0.70 ± 0.05, 1.01 ± 0.04, and 1.05 ± 0.03 for the six fractions. Osmotic reflection coefficients estimated from the minimal lymph-to-plasma concentration ratios were: 0.50 ± 0.03, 0.59 ± 0.02, 0.67 ± 0.04, 0.72 ± 0.03, 0.94 ± 0.01, and 0.96 ± 0.01 for the six protein fractions. The osmotic reflection coefficients are consistent with a two-pore exchange model possessing equivalent pore radii of 80 and 200 A. Theoretical considerations indicate that only the two largest protein fractions (100 A and 120 A radii) achieved filtration-independent concentrations in pulmonary lymph, even at the highest filtration rates. This suggests that the reported osmotic reflection coefficients of the four small protein fractions underestimate their true values. Circ Res 48: 549-561, 1981


Microvascular Research | 1977

Analysis of lymphatic protein flux data: I. Estimation of the reflection coefficient and permeability surface area product for total protein

Aubrey E. Taylor; D.Neil Granger; Robert A. Brace

Abstract The reflection coefficient (σP,f) and permeability surface area product (PSf) were determined using lymph total protein fluxes in three different vascular beds: lung, intestine, and hindpaw. When protein flux (JP), lymph flow (JL) and concentration of protein in lymph and plasma are substituted into the Kedem and Katchalsky equation, the following equation results: J P = (1 − σ P,f ) ( (C P + C L ) 2 )J V + PS (C P − C L ) . At each lymph flow and protein flux state the above equation is linear in σP,f and PSf. This method was used at several different lymph flow states in order to produce a family of lines relating σP,f and PSf in any given capillary bed. These linear equations were then solved either graphically or numerically to obtain a σP,f and PSf between any pair of protein flux states. For the intestine, σP,f varied between 0.3 and 0.9 using data from several published sources. For the hindpaw data, σP,f varied from 0.700 to 0.997. For the lung, only one σP,f could be calculated using this approach and the calculated value was 0.73. From our analyses, it is quite clear that σP,f is a function of the volume flow and is not equal to the osmotic filtration coefficient [σP,D of the relationship JV = KF,C(ΔP − σP,D Δπ)] except for a homoporous capillary membrane. At the present time we do not have the necessary data to analyze our approach fully and future work should analyze not only total protein but each protein fraction present in lymph collected at as many physiological steady states as possible.


Circulation Research | 1979

Analysis of the permeability characteristics of cat intestinal capillaries.

D N Granger; J P Granger; R A Brace; R E Parker; Aubrey E. Taylor

The permeability characteristics of cat small intestine capillaries were studied using both osmotic transient and lymph-to-plasma protein concentration ratio (L/P) techniques, A vascularly perfused segment of ileum in which superior mesenteric arterial pressure, blood flow, superior mesenteric venous pressure, and lymph flow were monitored was used for both determinations. Intestinal volume was continuously monitored during the osmotic transient experiments. Hyperosmotic solutions of various test solutes were infused at a constant rate directly into the superior mesenteric artery after the establishment of an isovolumetric state. Osmotic conductances were calculated from the initial rate of volume loss and the calculated plasma osmotic pressure change. Reflection coefficients for the various solutes were determined from the osmotic conductance and filtration coefficients within the same preparation. The predicted equivalent pore radius for intestinal capillaries using this approach is 200-350 A. In another group of cats, the L/P ratio for total plasma proteins was determined prior to and following graded increases in intestinal venous outflow pressure (10-30 mm Hg). At the greatest dilution of lymph proteins, the minimum osmotic reflection coefficient for total plasma proteins (ap) was estimated assuming ap = 1 - (Ci/Cp), and values of op between 0.87 and 0.92 were acquired. Minimum osmotic reflection coefficients for total plasma proteins were then determined during osmotic transients induced by hypertonic glucose (20-70 MM). Values of op between 0.56 and 0.74 were acquired during the osmotic transients. The results of these studies suggest that intestinal capillaries are relatively impermeable to endogenous plasma proteins. The discrepancy between the L/P ratio and osmotic transient techniques results, at least in part, from an increased capillary permeability during the osmotic transient. Circ Res 44: 335-344, 1979


Microvascular Research | 1977

Analysis of lymphatic protein flux data: II. Effect of capillary heteroporosity on estimates of reflection coefficients and PS products

Robert A. Brace; D.Neil Granger; Aubrey E. Taylor

Abstract In the first paper in this series we presented a direct method for estimating the capillary membrane reflection coefficient (σ) and permeability-surface area product ( PS ) for the plasma proteins using various lymph protein flux states. Basically, the method consisted of measuring lymph protein concentration and flow at two or more different flux states and solving the Kedem and Katchalsky equation for σ and PS for each pair of flux states. The present paper applies this method to data generated with a two-pore computer model where the pores have unequal reflection coefficients. The estimates of σ and PS for the model data display the same changes with venous pressure as those for experimental data. It is seen that the values of σ and PS calculated assuming a membrane is homoporous will most often significantly underestimate the true values of σ and PS if the membrane is heteroporous. Furthermore, it is shown that the capillary membrane cannot be characterized by a single value of σ since the reflection coefficient which describes protein movement σ f changes with filtration rate and is not generally equal to the reflection coefficient which describes fluid movement ( σ d ) across the capillary membrane.


Microvascular Research | 1977

Time course of lymph protein concentration in the dog

Robert A. Brace; Aubrey E. Taylor; Arthur C. Guyton

Abstract Lymph protein concentrations were measured in spontaneously flowing lymph collected from lymphatic ducts in the hind limb, forelimb, neck, and the left thoracic duct. Lymph from all ducts except the thoracic duct underwent a gradual increase in protein concentration of approximately 1 g/dl during the first 2 hr after anesthetization and remained constant during the subsequent 4 hr. After the protein concentration had increased to this high level, gentle massage of the area always caused a large increase in lymph flow and simultaneously a decrease in lymph protein concentration of approximately 1 g/dl after a flow of only 50 to 100 μl had occurred. Throughout the experiment, plasma protein concentration did not change. These data provide two separate indications that lymph protein concentration is not always identical to interstitial fluid. First, lymphatic protein concentration in a large fraction of the body increases while plasma protein concentration remains constant, which would be an impossibility if the protein concentration in the large volume of interstitial fluid increased. Second, lymphatic protein concentration following massage falls by approximately 1 g/dl when the volume and thus protein content of the interstitial fluid essentially has not changed at all.


Microvascular Research | 1977

Metabolism of coronary arteries and arterioles: A histochemical study☆

Billy H. Cook; Harris J. Granger; Aubrey E. Taylor

Abstract Because of sample size limitations, very little if any information is available concerning the biochemistry and metabolism of coronary arterioles. Using the histochemical approach, we studied glycolysis, β-oxidation of fatty acids, the Krebs cycle, and the respiratory chain in coronary arteriolar smooth muscle. In addition, the activities of myosin ATPase and other energy-consuming reactions were also determined. Our results suggest that the metabolism of coronary arterioles is predominately aerobic in nature with the strong possibility that fatty acids serve as the major energy source. The aerobic nature of microvascular metabolism is suggested by: (a) a low glycolytic potential as reflected in weak reactions for glycogen, α-glycerophosphate dehydrogenase, and lactate dehydrogenase; (b) high Krebs cycle activity as indicated by intensity of isocitrate, succinate, and malate dehydrogenase reactions; (c) high respiratory chain activity as reflected by heavy deposition of reaction products of ubiquinone and cytochrome oxidase; (d) preference for lipid as metabolic substrate as revealed by strong reactions for free fatty acids and β-hydroxybutyrate dehydrogenase. Myosin ATPase activity was greater in coronary arterioles than in the larger arteries, suggesting a more active contractile apparatus in the microvessels. When compared to the arterioles, the histochemical profile of small and intermediate coronary arteries revealed high potential for anaerobic glycolysis and very low oxidative activities. In view of this metabolic heterogeneity within the coronary vasculature, we suggest that data obtained from small coronary arteries cannot be extrapolated to the coronary microvasculature.


Journal of Surgical Research | 1978

Unchanged pulmonary capillary filtration coefficients after Escherichia coli endotoxin infusion

Joseph C. Gabel; Robert E. Drake; James F. Arens; Aubrey E. Taylor

Abstract The pulmonary capillary filtration coefficient ( K f,c ) was measured in intact, anesthetized dogs before and after the intravenous administration of alloxan and E. coli endotoxin. The method used to measure K f,c was that of determining the capillary filtration rate by analyzing the weight transient following a change in capillary pressure ( ΔP c ) and dividing the initial filtration rate by ΔP c . In four dogs given 75 mg/kg of alloxan, the K f,c increased 10-fold. This indicated that the capillary membranes were damaged by the alloxan and that, by using this method of measuring K f,c , changes in K f,c were easily detected. The K f,c , measured after a 3-hr continuous infusion of a total of 4 mg/kg of E. coli endotoxin [0.35 ± 0.21 (SD) ml/min/mm Hg/100g], was not different from the value found in the same animals before the endotoxin (0.33 ± 0.29). Since the K f,c is a sensitive indicator of capillary membrane pore size, these results strongly suggest that E. coli infusion did not damage the pulmonary capillary membrane.


Microvascular Research | 1976

Histochemistry of microvascular smooth muscle in the gastrointestinal tract

D.N. Granger; B.H. Cook; Harris J. Granger; Aubrey E. Taylor

Abstract Representative enzymes and substrates of the major metabolic pathways were analyzed and compared in submucosal arteriolar smooth muscle of the stomach, ileum, and colon by histochemical methods. Anaerobic glycolysis was represented by lactate dehydrogenase, the Krebs cycle by isocitrate dehydrogenase, and the respiratory chain by cytochrome oxidase. The hexose monophosphate shunt was represented by glucose-6-phosphate dehydrogenase, while fat utilization was demonstrated by β-hydroxybutyrate. Glycogen, cholesterol, free fatty acid, and neutral fat levels were also determined. The results of the study indicate that, in general, the ileal microvessels are metabolically more diverse than those of the stomach and colon. Unlike stomach and colon microvessels, arteriolar smooth muscle in the ileum maintains large endogenous stores of carbohydrates and fats. In addition, ileal microvessels possess a high potential for energy production via each of the major metabolic pathways. The metabolic profile of colonic microvessels was similar to that of ileum except for the absence of endogenous substrate stores. Stomach microvessels also lacked endogenous substrate stores; yet, unlike ileum and colon microvessels, no discernible glucose-6-phosphate dehydrogenase activity was determined for these vessels. The results of this study indicate that the metabolic machinery of vascular smooth muscle varies markedly between the functionally related organs of the gastrointestinal tract.


Journal of Surgical Research | 1967

Bidirectional movement of water through the skin of a nonsweating animal

William A. Neely; M.D. Turner; Aubrey E. Taylor

Abstract Exchange of water between body fluids and a saturated atmosphere was measured in dogs using D 2 O as the tracer. Bidirectional transfer rates were calculated from a series of eight experiments in which the tracer was placed first in the chamber. Outward diffusion of D 2 O averaged 32.5 ± 5.9 (S.D.) gm. per square meter per hour and inward 26 ± 13.4 gm. per square meter per hour. Outward transfer was calculated from a second series of nine experiments in which the D 2 O was injected intravenously into the dog and averaged in this series 34.5 ± 15.5 gm. per square meter per hour. Mean water loss through the skin of these nonsweating animals was greater than absorption even in a saturated atmosphere.

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Arthur C. Guyton

University of Mississippi Medical Center

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Harris J. Granger

University of Mississippi Medical Center

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Robert A. Brace

University of Mississippi Medical Center

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D.Neil Granger

University of Mississippi Medical Center

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B.H. Cook

University of Mississippi Medical Center

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D.N. Granger

University of Mississippi Medical Center

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James F. Arens

University of Mississippi Medical Center

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Joseph C. Gabel

University of Mississippi Medical Center

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Kiichi Sagawa

University of Mississippi Medical Center

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M.D. Turner

University of Mississippi Medical Center

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