Effect of hydration on lung interstitial conductivity response to electrically charged solutions.
ABSTRACT 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: 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. · 3.48 Impact Factor
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ABSTRACT: Please cite this paper as: Dongaonkar RM, Stewart RH, Quick CM, Uray KL, Cox CS, Laine GA. Time course of myocardial interstitial edema resolution and associated left ventricular dysfunction. Microcirculation 19: 714–722, 2012. AbstractObjective: Although the causal relationship between acute myocardial edema and cardiac dysfunction has been established, resolution of myocardial edema and subsequent recovery of cardiac function have not been established. The time to resolve myocardial edema and the degree that cardiac function is depressed after edema resolves are not known. We therefore characterized temporal changes in cardiac function as acute myocardial edema formed and resolved.Methods: Acute myocardial edema was induced in the canine model by elevating coronary sinus pressure for three hours. Myocardial water content and cardiac function were determined before and during coronary sinus pressure elevation, and after coronary sinus pressure restoration.Results: Although no change in systolic properties was detected, accumulation of water in myocardial interstitium was associated with increased diastolic stiffness. When coronary sinus pressure was relieved, myocardial edema resolved within 180 minutes. Diastolic stiffness, however, remained significantly elevated compared with baseline values, and cardiac function remained compromised.Conclusions: The present work suggests that the cardiac dysfunction caused by the formation of myocardial edema may persist after myocardial edema resolves. With the advent of new imaging techniques to quantify myocardial edema, this insight provides a new avenue for research to detect and treat a significant cause of cardiac dysfunction.Microcirculation (New York, N.Y.: 1994) 11/2012; 19(8). · 2.37 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. · 2.93 Impact Factor