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Biomedical subjects

F E Curry

Publications and source records attributed to F E Curry.

At least 73 records · Page 4Linked to original sources
PubMed1983

Permeability of single capillaries to intermediate-sized colored solutes.

The fiber matrix theory of capillary permeability was evaluated by measuring permeability coefficients to colored solutes with Stokes radii between 0.5 and 1.76 nm. In vivo calibration of a microscope photometer established the range of linearity for optical density measurements from a rectangular window that included the test capillary and surrounding tissue. In individually perfused capillaries of frog mesentery the following permeability coefficients, expressed as mean +/- SE X 10(5) cm/s were obtained: azure C (mol wt 277), 11.0 +/- 0.2; patent blue violet (566), 3.95 +/- 0.67; Evans blue (960), 1.15 +/- 0.23; microperoxidase (1,900), 1.13 +/- 0.31; and FITC-dextran 3 (3,400), 0.48 +/- 0.18. There is significant restriction to diffusion of all solutes larger than azure C. Fibers 0.5 nm in radius occupying 8.5% of the volume of intercellular junctions (area 2.2 X 10(-3) cm2/cm2, depth 0.6 X 10(-4) cm) account for the 22-fold range of measured permeabilities. The fiber density estimated is larger than that required to describe water flow through the junction. Negative charges on solutes larger than 0.5 nm radius may contribute to exclusion and restriction to diffusion in intercellular junctions.

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PubMed1981

Effect of temperature on hydraulic conductivity of single capillaries.

Paired determinations of the hydraulic conductivity (Lv) of individually perfused capillaries in frog mesentery were measured at 22-25 and 5-8 degrees C. The mean value of the ratio of the hydraulic conductivity at 22-25 to that at 5-8 degrees C was 1.76 +/- 0.22 (SE) in 10 capillaries perfused with albumin in the Ringer perfusate and 1.81 +/- 0.11 in six capillaries perfused with Ringer alone. The ratio of Lp can be accounted for in terms of a 1.60-fold increase in water viscosity between 22-25 and 5-8 degrees C. The results conform to the hypothesis that the structure of the principal pathway for water across the capillary wall is invariant with temperature; models of the water pathway that imply a change in the number of pathways or a change in pathway structure with temperature are incompatible with these results. Temperature gradients across the tissue are negligible in these experiments; calculations show that in the presence of temperature gradients, which occur during tissue cooling or rewarming, transcapillary water flows due to thermoosmosis are likely to occur.

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PubMed1981

Antipyrine and aminopyrine permeability of individually perfused frog capillaries.

The mechanisms of transport of water and solutes across both hydrophilic and lipophilic pathways in the capillary wall were investigated. Paired measurements of the osmotic reflection and solute permeability coefficients of a lipid soluble solute (antipyrine MW 188 or aminopyrine 231) and a hydrophilic solute (glucose 180) were made on individually perfused capillaries of frog mesentery at temperatures between 5 and 25 degrees C. Below 15 degrees C, the lipophilic pathway accounts for less than 10% of the flux of antipyrine across the capillary wall, whereas at 25 degrees C the lipophilic pathway accounts of 50% of the flux. These results conform to the hypothesis that water and both hydrophilic and lipophilic solutes share an extracellular pathway, but water and lipids cross the cell by entirely separate routes. Both the activation energy for antipyrine and aminopyrine diffusion in the lipophilic pathway (25.9 kcal/mol) and the estimated cell membrane-water partition coefficients of the solutes are similar to values found for mammalian erythrocytes. Lateral diffusion in the cell membranes would account for the lipophilic pathway permeability just as well as diffusion across the cell membranes.

Aminopyrine↗
PubMed1979

The ultrastructure of frog mesenteric capillaries of known filtration coefficient.

The capillaries of the frog mesentery were investigated by transmission electronmicroscopy. The mean diameter of these vessels was 20 micrometers and a single layer of five to six endothelial cells (on average) contributed to each circumference. Their ultrastructure was very similar to that of mammalian capillaries of the continuous type [Bennett, Luft and Hampton, 1959]. The endotherlial cells, which contained many vesicles, were joined by specialized junctions and surrounded by a continuous basement membrane. Eleven capillaries were examined after the filtration coefficient of their walls had been investigated by the microperfusion micro-occlusion technique of Michel, Mason, Curry and Tooke [1974]. No abnormal appearances were observed even after the vessels had been perfused with protein free solutions which have been shown to increase filtration coefficient five fold. No morphological differences between capillaries were seen to accompany large differences in the filtration coefficients.

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PubMed1976

Osmotic reflextion coefficients of capillary walls to low molecular weight hydrophilic solutes measured in single perfused capillaries of the frog mesentery.

1. Individual capillaries of the transilluminated frog mesentery have been perfused with suspensions of human red cells in frog Ringer solution containing 1-0 g albumin 100 ml.-1. The outer surface of the mesentery has been washed with normal frog Ringer solution and with frog Ringer solutions made hypertonic by addition of one of the following solutes: sodium chloride (100 m-mole. 1.-1); urea (100 m-mole.1.-1); sucrose (20-50 m-mole. 1.-1); cyanocobalamin (8-5 m-mole. 1.-1). The temperature of the mesentery was between 14 and 16 degrees C in all experiments. 2. Wtih the mesentery superfused with normal Ringer, the filtration coefficient was determined from measurements of the rate of fluid filtration across the capillary wall, at a series of known capillary pressures (Michel, Mason, Curry & Tooke, 1974). Filtration coefficient varied from 0-69 X 10(-3) to 4-45 X 10(-3) mum. sec-1 .cm H2O-1 with an average value of 1-87 X 10(-3) mum. sec-1. cm H2O-1. 3. When the superfusate was made hypertonic by the addition of a test solute, the osmotic reflextion coefficient (sigma) of the capillary wall to test solute was calculated from the additional rate of filtration, the concentration of test solute in the superfusate and the filtration coefficient. Average values for sigma were: sodium chloride, 0-068 +/- 0-03 (three capillaries); urea, 0-071 +/- 0.015 (four capillaries); sucrose, 0-115 +/- 0-023 (seven capillaries); cyanocobalamin, 0-100 +/- 0-03 (three capillaries). 4. In further experiments, the osmotic reflextion coefficients to sodium chloride, urea and sucrose were determined in the same capillary. Five technically acceptable experiments were carried out. Although there were differences in the value of sigma between different capillaries, in any one capillary values of sigma were of the same magnitude and there appeared to be no significant trend with the molecular size of the test solute. 5. Our findings are inconsistent with the hypothesis that there is a single pathway for water and small hydrophilic molecules across the capillary wall. 6. Our results may be interpreted in terms of an exclusive channel for water in parallel with a channel shared by both water and small hydrophilic molecules. It is suggested that the exclusive water channel may be the membranes and cytoplasm of the endothelial cells and the shared channel may be located in the intercellular junctions. 7. Our data suggest the exclusive water channel represents about 10% of the total filtration coefficient in frog mesenteric capillaries. The shared channel shows relatively little restriction to the molecules investigated. Estimates of the volume flow throught the two channels are made for conditions where hydrostatic pressure differences and osmotic pressure differences are the driving forces.

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