Water flow across the walls of single muscle capillaries in the frog, Rana pipiens.

Curry, F. E.; J, Frøkjaer-Jensen

doi:10.1113/jphysiol.1984.sp015202

Cited by 33 publications

(17 citation statements)

References 22 publications

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“…The value for Lp found in the present experiments is very much lower than that of other endothelia (3 % of that found for frog skeletal muscle and 0 4 % of that found for mesenteric microvessels, see (Curry & Froekjaer-Jensen, 1984). The value obtained in the present study is similar to that found in mammals (Fenstermacher & Johnson, 1967;Paulson, Hertz, Bolwig & Lassen, 1977) in which the whole brain microvasculature was assessed, and is compatible with many of the measurements for cell membranes.…”

Section: Assessment Of Techniquesupporting

confidence: 76%

Measurement of filtration coefficient in single cerebral microvessels of the frog.

Fraser

Dallas

Davies

1990

The Journal of Physiology

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SUMMARY1. This study reports the first results of measurements of filtration coefficient (LP) and osmotic reflection coefficient to sucrose (oauk) in single brain microvessels.2. Microvessels on the surface of frog brain were cannulated with a micropipette and perfused with an artificial cerebrospinal fluid (CSF) containing the low molecular weight impermeant dye carboxyfluorescein (MW 376). The superfusing solution was a similar CSF which could be made hypertonic by the addition of 40-125 mmol 1I sucrose.3. Vessels were assessed for dye retention using video-intensified microscopy after occlusion with a glass microneedle. Only six vessels out of a total of ninety-five were tight under the experimental conditions used. Those vessels which were tight were occluded while an osmotic load was applied across them. When this load was 50 mosmol 11 and less, the steady-state dye concentration within the vessel lumen was similar to that predicted assuming the endothelium behaves as a perfect semipermeable membrane, with concentration polarization of solute.4. The product L or was estimated in two ways: (i) from the fitted monoexponential function that described the rising dye concentration within the occluded segment, and (ii) from the initial rate of increase in dye concentration. The two values obtained were similar and it was concluded that 0(NaC1 = -suc = 1, and the best estimate for filtration coefficient Lp = 2-0 x 10-cm (cmH2O s)-1.5. At the osmotic loads of 100 mosmol 1I1 and more, the initial rate of increase estimate of Lp o was less than half of the whole curve estimate, the axial dye distributions were dissimilar from those predicted by a mathematical model based on the perfect semipermeable membrane, and the steady-state concentration was less than 70 % of that expected. These findings are consistent with a diffusive pathway having opened. The model was modified to include patches of vessel wall which had developed leaks and a good fit to the data was obtained with a sucrose permeability and an Lp similar to skeletal muscle endothelium.6. The possibility that water passes through a paracellular pathway across the intact blood-brain barrier is discussed. It is concluded that this pathway could not

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Section: Assessment Of Techniquesupporting

confidence: 76%

Measurement of filtration coefficient in single cerebral microvessels of the frog.

Fraser

Dallas

Davies

1990

The Journal of Physiology

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“…First, while a change of capillary volume does follow a change in P, this change is rapid and when P, is greater than 10 cmH2O it is usually complete within 1 s (Michel et al 1974;Mason, 1976;Michel, 1980;Curry & Fr0kjaer-Jensen, 1984). In our micro-occlusion experiment this initial rapid movement of the red cell flow markers was not used to estimate transcapillary fluid movement.…”

Section: Discussionmentioning

confidence: 99%

“…In order to have rapid initial perfusion of the capillary and yet measure fluid movements across the capillary wall at pressures of 10-15 cmH2O, the pressure applied to the pipette for the initial perfusion was set initially at 30-35 cmH2O and then dropped into the desired range by the turn of a tap connected to a second manometer maintained at the lower pressure. On lowering the pressure, the immediate movement of the red cells reflected a rapid reduction of volume of the capillary (compliance effect) but this was usually complete within 1-2 s (Michel et al 1974;Mason, 1976;Smaje & Swayne, 1983;Curry & Fr0kjaer-Jensen, 1984 It is worth noting that for BSA, oC estimated from the transient data has a value of 0-76 (S.E. of mean + 004) and from the steady-state data has a value of 0-75 (S.E.…”

Section: Measurements Offluid Filtration In Single Capillariesmentioning

confidence: 99%

Steady‐state fluid filtration at different capillary pressures in perfused frog mesenteric capillaries.

Michel

Phillips

1987

The Journal of Physiology

128

101

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SUMMARY1. The theory of steady-state filtration through capillary walls (Michel, 1984) P, less than the perfusate oncotic pressure, the transient data showed reabsorption of fluid from the tissues, but in the steady state either fluid movements were so small as to be undetected or slight filtration was observed. The steady-state data followed the pattern predicted by theory.4. The transient data were used to estimate the reflection coefficient ofthe capillary wall (o-) to the macromolecular solute. In seven vessels, the mean o-to BSA was 0-76 (S.E. of mean + 0-04) and in eight different vessels mean a to Ficoll 70 in the presence of BSA (10 mg ml-') was 0-98 (s.E. of mean +0 05). The steady-state data were consistent with the prediction that the oncotic pressure opposing high filtration rates approximates to o-21Ic in the steady state, where Hc is the perfusate oncotic pressure.

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“…Because hyperosmolarity may affect capillary permeability (Granger et al 1979;Rasio, Bendayan & Goresky, 1981;Friedman & DeRose, 1982; but cf. Theven, Xuan, Vallois, Syrota & Pocidalo, 1982;Curry & Frokjaer-Jensen, 1984), hyperosmolar perfusions were always performed last. Osmotic transients have been described for continuous capillaries (e.g.…”

Section: Model Of Trans-synovialflowmentioning

confidence: 99%

Relation Between Trans‐synovial Flow and Plasma Osmotic Pressure, With an Estimation of the Albumin Reflection Coefficient in the Rabbit Knee

1988

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SUMMARYThe volume of synovial fluid in a joint correlates inversely with plasma colloid osmotic pressure (COP). The inferred influence of plasma osmotic forces on trans-synovial flow was investigated directly here, in isolated perfused hindquarters of sixteen rabbits. Flow of intra-articularly infused Krebs solution across the synovial lining of the cannulated knee was recorded at controlled intra-articular pressure (18 cmH2O). Colloid osmotic pressure in the synovial microcirculation was varied by perfusion with oxygenated red cells resuspended in albumin solution or plasma from an extra-corporeal system at constant perfusion pressure. Studies in vitro showed that the COP versus concentration curve for commercial bovine albumin samples was variable and not reliably described by a widely used polynomial. The rate of trans-synovial absorption Qs was a positive linear function of intravascular COP T,, (r = 0-936, P < 0 001, n = 83). The average slope dQ,/dl7T was 0-20 ,ul min-' cmH20-' (S.E. + 0-01 lld min-, cmH201), the slope depending on hydraulic conductance and osmotic reflection coefficient. Transsynovial flow was a negative linear function of synovial capillary pressure (Pc). Absolute slope dQ,/d7Tp was on average only 78% of dQ8/dP, in the same joint. The osmotic reflection coefficient of the blood-joint barrier to serum albumin was estimated from these slopes as 0-78-0-81 (S.E.M. + 0 06). Vascular perfusion with a hyperosmolar solution of glucose, sucrose or NaCl generated a transient, rapidly decaying osmotic absorption from the joint cavity, with a half-life of 17-60 s. A reversed osmotic transient occurred on reperfusion with isotonic fluid. It was concluded that the blood-joint barrier, which comprises fenestrated endothelium and synovial intima, approximates to an imperfect semipermeable membrane for albumin solutions, justifying the application of Starling's hypothesis to trans-synovial flow. For small solutes the tissues form a highly permeable but nevertheless slightly osmotically reflective membrane.

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Water flow across the walls of single muscle capillaries in the frog, Rana pipiens.

Cited by 33 publications

References 22 publications

Measurement of filtration coefficient in single cerebral microvessels of the frog.

Measurement of filtration coefficient in single cerebral microvessels of the frog.

Steady‐state fluid filtration at different capillary pressures in perfused frog mesenteric capillaries.

Relation Between Trans‐synovial Flow and Plasma Osmotic Pressure, With an Estimation of the Albumin Reflection Coefficient in the Rabbit Knee

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