Regulation of extracellular volume and interstitial fluid pressure in rat bone marrow

The volume and fluid pressure characteristics of the intact bone marrow is incompletely understood. We used microspheres and lipoproteins for measurements of intravascular volume (IVV) and EDTA for interstitial fluid volume (IFV) within the rat bone marrow. Interstitial fluid pressure (IFP) was determined with micropipettes connected to a servo-controlled counter-pressure system. Both the microspheres and the lipoproteins yielded estimates of IVV of ∼1 ml/100 g. After a brief reactive hyperemia, IVV increased to 2.5 ml/100 g, whereas IFV decreased with ∼1.5 ml/100 g, so that total extracellular volume did not change. Baseline bone marrow IFP was 9.7 mmHg. The hyperemia led to a transient twofold increase in IFP, whereas a marked blood loss decreased IFP by almost one-half. These novel data suggest that extracellular volume and IFP within the bone marrow can be measured with tracer methods and the micropuncture technique. The responses of IVV, IFV, and IFP during changes in blood flow to the bone marrow suggest a tight regulation and are thus compatible with those for a low-compliant tissue.

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Interstitial fluid pressure, composition of interstitium, and interstitial exclusion of albumin in hypothyroid rats

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2000.278.5.h1627 ◽

2000 ◽

Vol 278 (5) ◽

pp. H1627-H1639 ◽

Cited By ~ 39

Author(s):

Helge Wiig ◽

Rolf K. Reed ◽

Olav Tenstad

Keyword(s):

Thyroid Hormones ◽

Interstitial Fluid ◽

Fluid Pressure ◽

Interstitial Fluid Pressure ◽

Albumin Concentration ◽

Rat Serum ◽

Interstitial Fluid Volume ◽

Hindlimb Muscle ◽

The Difference ◽

And Control

Lack of thyroid hormones may affect the composition and structure of the interstitium. Hypothyrosis was induced in rats by thyroidectomy 4–12 wk before the experiments. In hypothyroid rats ( n = 16), interstitial fluid pressure measured with micropipettes in hindlimb skin and muscle averaged +0.1 ± 0.2 and +0.5 ± 0.2 mmHg, respectively, with corresponding pressures in control rats ( n = 16) of −1.5 ± 0.1 ( P < 0.001) and −0.8 ± 0.1 mmHg ( P < 0.001). Interstitial fluid volume, measured as the difference between the distribution volumes of 51Cr-EDTA and125I-labeled BSA, was similar or lower in skin and higher in hypothyroid muscle. Total protein and albumin concentration in plasma and interstitial fluid (isolated from implanted wicks) was lower in hypothyroid compared with control rats. Hyaluronan content ( n = 9) in rat hindlimb skin was 2.05 ± 0.15 and 1.92 ± 0.09 mg/g dry wt ( P > 0.05) in hypothyroid and control rats, respectively, with corresponding content in hindlimb skeletal muscle of 0.35 ± 0.07 and 0.23 ± 0.01 mg/g dry wt ( P < 0.01). Interstitial exclusion of albumin in skin and muscle was measured after 125I-labeled rat serum albumin infusion for 120–168 h with an implanted osmotic pump. Relative excluded volume for albumin (Ve/Vi) was calculated as 1 − Va/Vi, and averaged 28 and 28% in hindlimb muscle ( P > 0.05), 44 and 45% in hindlimb skin ( P > 0.05), and 19 and 32% in back skin ( P < 0.05) in hypothyroid and control rats, respectively. Albumin mass was higher in back skin in spite of a lower interstitial fluid albumin concentration, a finding explained by a reduced Ve/Vi in back skin in hypothyroid rats. These experiments suggest that lack of thyroid hormones in rats changes the interstitial matrix again leading to reduced interstitial compliance and changes in the transcapillary fluid balance.

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Balance point characterization of interstitial fluid volume regulation

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00097.2009 ◽

2009 ◽

Vol 297 (1) ◽

pp. R6-R16 ◽

Cited By ~ 23

Author(s):

R. M. Dongaonkar ◽

G. A. Laine ◽

R. H. Stewart ◽

C. M. Quick

Keyword(s):

Fluid Balance ◽

Interstitial Fluid ◽

Fluid Pressure ◽

Fluid Volume ◽

Interstitial Fluid Pressure ◽

Lymphatic Function ◽

Balance Point ◽

Interstitial Fluid Volume ◽

Algebraic Solutions

The individual processes involved in interstitial fluid volume and protein regulation (microvascular filtration, lymphatic return, and interstitial storage) are relatively simple, yet their interaction is exceedingly complex. There is a notable lack of a first-order, algebraic formula that relates interstitial fluid pressure and protein to critical parameters commonly used to characterize the movement of interstitial fluid and protein. Therefore, the purpose of the present study is to develop a simple, transparent, and general algebraic approach that predicts interstitial fluid pressure ( P i) and protein concentrations ( C i) that takes into consideration all three processes. Eight standard equations characterizing fluid and protein flux were solved simultaneously to yield algebraic equations for P i and C i as functions of parameters characterizing microvascular, interstitial, and lymphatic function. Equilibrium values of P i and C i arise as balance points from the graphical intersection of transmicrovascular and lymph flows (analogous to Guyton's classical cardiac output-venous return curves). This approach goes beyond describing interstitial fluid balance in terms of conservation of mass by introducing the concept of inflow and outflow resistances. Algebraic solutions demonstrate that P i and C i result from a ratio of the microvascular filtration coefficient (1/inflow resistance) and effective lymphatic resistance (outflow resistance), and P i is unaffected by interstitial compliance. These simple algebraic solutions predict P i and C i that are consistent with reported measurements. The present work therefore presents a simple, transparent, and general balance point characterization of interstitial fluid balance resulting from the interaction of microvascular, interstitial, and lymphatic function.

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Increased negativity of interstitial fluid pressure in rat trachea after mast cell degranulation

Journal of Applied Physiology ◽

10.1152/jappl.1993.74.5.2135 ◽

1993 ◽

Vol 74 (5) ◽

pp. 2135-2139 ◽

Cited By ~ 32

Author(s):

M. E. Koller ◽

K. Woie ◽

R. K. Reed

Keyword(s):

Mast Cell ◽

Interstitial Fluid ◽

Control Level ◽

Fluid Pressure ◽

Polymyxin B ◽

Mast Cell Degranulation ◽

Interstitial Fluid Pressure ◽

Tissue Water ◽

Edema Formation ◽

Interstitial Fluid Volume

The present study was performed to investigate whether the increased negativity of interstitial fluid pressure (Pif) observed after intravenous injection of dextran could be mediated via mast cell degranulation induced by C48/80 and polymyxin B sulfate. Increased negativity of Pif, concomitant with edema formation and increased albumin extravasation, was seen with both substances. However, the two substances differed in that polymyxin B sulfate induced less negativity in Pif and a larger but transient increase in capillary albumin extravasation and interstitial fluid volume. Total tissue water (TTW) increased from 2.11 to 2.71 ml/g dry wt 10 min after polymyxin B and returned to control level at 30 and 60 min. Injection of C48/80 increased TTW to 2.68 ml/g dry wt at 30 min, and TTW was still elevated at 60 min. Albumin extravasation followed a similar pattern; polymyxin B sulfate increased albumin extravasation from < 0.08 to 1.18 ml/g dry wt during the first 5 min after administration. C48/80 was less potent, and maximal albumin leakage was seen after 10–25 min (0.25 ml/g dry wt). The observations demonstrate the importance of the interstitium and the loose connective tissues as "active" participants in the edema-generating process and suggest an interaction with the structural components of the interstitium, as well as an important role for the mast cells in the chain of events creating increased negativity of Pif.

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Interstitial Fluid Pressure in Control of Interstitial Fluid Volume During Normal Conditions, Injury and Inflammation

Mechanics of Swelling ◽

10.1007/978-3-642-84619-9_27 ◽

1992 ◽

pp. 475-485

Author(s):

R. K. Reed ◽

H. Wiig ◽

T. Lund ◽

S. Å. Rodt ◽

M.-E. Roller ◽

...

Keyword(s):

Interstitial Fluid ◽

Fluid Pressure ◽

Fluid Volume ◽

Interstitial Fluid Pressure ◽

Interstitial Fluid Volume

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Increased negativity of interstitial fluid pressure in rat trachea in dextran anaphylaxis

Journal of Applied Physiology ◽

10.1152/jappl.1992.72.1.53 ◽

1992 ◽

Vol 72 (1) ◽

pp. 53-57 ◽

Cited By ~ 26

Author(s):

M. E. Koller ◽

R. K. Reed

Keyword(s):

Interstitial Fluid ◽

Circulatory Arrest ◽

Fluid Pressure ◽

Fluid Volume ◽

Interstitial Fluid Pressure ◽

Tracheal Mucosa ◽

Interstitial Fluid Volume ◽

Dextran 70 ◽

Mean Pressure ◽

Rat Trachea

This study shows that, in rat trachea, dextran anaphylaxis is associated with increased negativity of interstitial fluid pressure (Pif) as measured with sharpened glass capillaries (tip diameter 3–7 microns) connected to a servo-controlled counterpressure system. Experiments were carried out in pentobarbital-anesthetized Wistar-Moller rats. Pif in the control situation was -2.5 +/- 0.38 (SD) mmHg. The mean pressure in animals killed 2 min after initiation of the anaphylactic reaction by injection of 1 ml of 10% Dextran 70 in 0.9% NaCl was -10.3 +/- 2.6 mmHg. In another experimental series, interstitial fluid volume was measured after dextran administration but without inducing circulatory arrest. Interstitial fluid volume increased from 0.94 +/- 0.16 to 1.56 +/- 0.42 ml/g dry wt after 10 min to 1.57 +/- 0.30 and 1.10 +/- 0.27 ml/g dry wt after 30 and 60 min, respectively. The increased negativity in Pif in tracheal mucosa in the early phase of dextran anaphylaxis will markedly increase the transcapillary net filtration pressure in the initial phase of edema development.

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Control of interstitial fluid pressure: Role of [beta ]-integrins

Seminars in Nephrology ◽

10.1053/snep.2001.21646 ◽

2001 ◽

Vol 21 (3) ◽

pp. 222-230 ◽

Cited By ~ 42

Author(s):

Rolf K. Reed ◽

Ansgar Berg ◽

Eli-Anne B. Gjerde ◽

Kristofer Rubin

Keyword(s):

Interstitial Fluid ◽

Fluid Pressure ◽

Interstitial Fluid Pressure

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Dynamics of Interstitial Fluid Pressure in Extracellular Matrix Hydrogels in Microfluidic Devices

Journal of Biomechanical Engineering ◽

10.1115/1.4031020 ◽

2015 ◽

Vol 137 (9) ◽

Cited By ~ 5

Author(s):

Joe Tien ◽

Le Li ◽

Ozgur Ozsun ◽

Kamil L. Ekinci

Keyword(s):

Extracellular Matrix ◽

Pressure Distribution ◽

Interstitial Fluid ◽

Scaling Laws ◽

Fluid Pressure ◽

Interstitial Fluid Pressure ◽

External Loading ◽

Interstitial Pressure ◽

Time Resolved ◽

Long Time

In order to understand how interstitial fluid pressure and flow affect cell behavior, many studies use microfluidic approaches to apply externally controlled pressures to the boundary of a cell-containing gel. It is generally assumed that the resulting interstitial pressure distribution quickly reaches a steady-state, but this assumption has not been rigorously tested. Here, we demonstrate experimentally and computationally that the interstitial fluid pressure within an extracellular matrix gel in a microfluidic device can, in some cases, react with a long time delay to external loading. Remarkably, the source of this delay is the slight (∼100 nm in the cases examined here) distension of the walls of the device under pressure. Finite-element models show that the dynamics of interstitial pressure can be described as an instantaneous jump, followed by axial and transverse diffusion, until the steady pressure distribution is reached. The dynamics follow scaling laws that enable estimation of a gel's poroelastic constants from time-resolved measurements of interstitial fluid pressure.

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