Effect of hydration on lung interstitial conductivity response to electrically charged solutions
Wenner-Gren Research Laboratory, University of Kentucky, Lexington 40506-0070, USA.Respiration Physiology 10/1997; 109(3):261-72. DOI: 10.1016/S0034-5687(97)00061-3
In interstitial segments of rabbit lung, we compared the flow of a solution containing cationic protamine sulfate (0.08 mg/ml) or cationic dextran (0.1%) to that of Ringer or neutral dextran solution. Also compared, were the flow of solutions containing anionic dextran (0.1 or 1.5%) to those containing neutral dextran and the flow of hyaluronidase solution (0.02%) to that of Ringer solution, at mean interstitial pressures (Pm) between -5 and 15 cmH2O. Driving pressure was set at 5 cmH2O. Cationic protamine or cationic dextran-to-Ringer flow ratio increased with Pm (presumably as hydration increased) but in nonedematous interstitium (-5 cmH2O Pm), flow ratio was 1, indicating a viscosity-dependent flow. In contrast, the flow of anionic dextran solution decreased relative to that of neutral dextran; this decrease was constant with hydration, but was greater at the higher concentration of dextran. Interstitial conductivity to the flow of hyaluronidase increased with hydration. However, this behavior was absent after the flow of 1.5% anionic dextran, indicating an inhibitory effect of the higher concentration of anionic dextran on the hyaluronidase response. A negative charge in microvascular filtrate may control fluid clearance in normal interstitium, while a positive charge would enhance clearance only in edema formation.
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ABSTRACT: Albumin diffusion measured in an isolated segment of rabbit lung interstitium with a radioactive tracer ((125)I-albumin) technique was independent of albumin concentration and similar to the free diffusion of albumin in water (Qiu et al, 1998. J Appl Physiol 85: 575-583). We studied the effect of hyaluronidase on the diffusion of albumin. Isolated rabbit lungs were inflated with silicon rubber by way of airways and blood vessels, and two chambers were bonded to the sides of a approximately 0.5-cm thick slab enclosing a vessel with an interstitial cuff. One chamber was filled with 2 g/dl albumin solution containing (125)I-albumin and 0.02 g/dl hyaluronidase. Unbound (125)I was removed from the tracer by dialysis before use. The other chamber filled with Ringer's solution was placed within a NaI(Tl) scintillation detector. Diffusion of tracer was measured continuously for 120 h. Albumin diffusion coefficient (D) and interstitial area (A) were obtained by fitting the tracer-time curve with the theoretical solution of the equation describing one-dimension diffusion of a solute across a membrane. D averaged 5.2 x 10(-7) cm(2)/s for albumin diffusion with hyaluronidase, 20% less than that measured previously without hyaluronidase. Hyaluronidase had no effect on A. Results indicated an interaction between albumin and interstitial hyaluronan that was the opposite of the steric effect on albumin excluded volume measured in solution.Beiträge zur Klinik der Tuberkulose 02/1999; 177(5):273-88. DOI:10.1007/PL00007647 · 2.27 Impact Factor
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ABSTRACT: In previous studies, the flow of albumin solution through hydrated lung interstitial segments was higher than a prior flow of Ringer solution (A. Tajaddinni et al., 1994, J. Appl. Physiol. 76, 578-583). We wondered whether this effect was caused by an increased pore size. We measured the flow of albumin solutions through interstitial segments subjected to a driving pressure of 5 cm H(2)O and various mean interstitial pressures (P(if)). The ratio of albumin concentration (C(alb)) of the output solution to that of the input solution (C(out)/C(in), sieving ratio) was measured using tracer (125)I-albumin. At normal hydration (0 cm H(2)O P(if)), C(out)/C(in) was minimal (0.6) with the flow of Ringer solution, increased to 0.8 with the flow of 5 g/dl albumin solution, and increased to 1 with increased hydration at 15 cm H(2)O P(if). We modeled the interstitium as a membrane subjected to flows of high Peclet numbers. Accordingly, the albumin reflection coefficient [sigma = 1 - (C(out)/C(in))] at 0 cm H(2)O P(if) was 0.4 with the flow of Ringer solution and decreased to 0 at 5 g/dl C(alb) and 15 cm H(2)O P(if). This behavior suggests that the flow of albumin occurred through interstitial pores that increased in size as either C(alb) or hydration increased. We conceive of an interstitium that consists of pores with permeable moveable walls across which osmotic interaction occurs between the pore liquid and the surrounding tissue.Microvascular Research 02/2002; 63(1):27-40. DOI:10.1006/mvre.2001.2363 · 2.13 Impact Factor
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ABSTRACT: The growth rate and albumin concentration of interstitial fluid cuffs were measured in isolated rabbit lungs inflated with albumin solution (3 g/dl) to constant airway (Paw) and vascular pressures for up to 10 h. Cuff size was measured from images of frozen lung sections, and cuff albumin concentration (Cc) was measured from the fluorescence of Evans blue labeled albumin that entered the cuffs from the alveolar space. At 5-cmH2O Paw, cuff size peaked at 1 h and then decreased by 75% in 2 h. The decreased cuff size was consistent with an osmotic absorption into the albumin solution that filled the vascular and alveolar spaces. At 15-cmH2O Paw, cuff size peaked at 0.25 h and then remained constant. Cc rose continuously at both pressures, but was greater at the higher pressure. The increasing Cc with a constant cuff size was modeled as diffusion through epithelial pores. Initial Cc-to-airway albumin concentration ratio was 0.1 at 5-cmH2O Paw and increased to 0.3 at 15 cmH2O, a behavior that indicated an increased permeability with lung inflation. Estimated epithelial reflection coefficient was 0.9 and 0.7, and equivalent epithelial pore radii were 4.5 and 6.1 nm at 5- and 15-cmH2O Paw, respectively. The initial cuff growth occurred against an albumin colloid osmotic pressure gradient because a high interstitial resistance reduced the overall epithelial-interstitial reflection coefficient to the low value of the interstitium.Journal of Applied Physiology 02/2004; 96(1):283-92. DOI:10.1152/japplphysiol.00581.2003 · 3.06 Impact Factor
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