Document Detail

Influence of actin cytoskeleton on intra-articular and interstitial fluid pressures in synovial joints.
MedLine Citation:
PMID:  11678632     Owner:  NLM     Status:  MEDLINE    
Fibroblast microfilamentous actin (F-actin) influences interstitial fluid pressure via linkages to collagen in rat skin (Berg et al., 2001). The present aims were to determine whether the actin cytoskeleton of synovial endothelium, fibroblasts, and synoviocytes influences in vivo (i) fluid exchange between a joint cavity and synovial microcirculation and (ii) extracellular fluid pressures in joints. Rabbit knee joints were treated intra-articularly with the F-actin disrupting drugs cytochalasin D and latrunculin B while joint fluid pressure P(j) was recorded. In joints injected with small volumes of control solution, P(j) fell with time (-0.05 +/- 0.01 cm H2O x min(-1), mean +/- SEM, n = 9, equivalent drainage rate 3.9 microl x min(-1)). Cytochalasin or latrunculin reversed this in approximately 4 min in vivo; P(j) increased with time, e.g., +0.12 +/- 0.04 cm H2O x min(-1) at 200 microM cytochalasin (equivalent filtration rate into joint 6.6-12.5 microl x min(-1), n = 4), with a cytochalasin EC50 of 45 microM. Plasma gamma-globulin clearance into the joint cavity was also increased. Post mortem, cytochalasin did not reverse dP(j)/dt and had no more effect on P(j) than did control solution. Also, when synovial interstitial fluid pressures were measured by servonull micropipette post mortem (control -0.95 +/- 0.37 cmH2O, n = 18) cytochalasin had no significant effect on interstitial pressure over 60 min, even at 1 mM. It was concluded that synovial endothelial F-actin has an important role in the normal synovial microvascular resistance to fluid filtration and plasma gamma-globulin permeation and is thus a potential link between pro-inflammatory mediators and arthritic joint effusions. The results provided no support for the hypothesis that synoviocyte F-actin influences the swelling tendency of synovial matrix and hence extracellular fluid pressures, in contrast to the findings of Berg et al. (2001) in rat dermis.
A Poli; D Scott; K Bertin; G Miserocchi; R M Mason; J R Levick
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Microvascular research     Volume:  62     ISSN:  0026-2862     ISO Abbreviation:  Microvasc. Res.     Publication Date:  2001 Nov 
Date Detail:
Created Date:  2001-10-26     Completed Date:  2002-01-31     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0165035     Medline TA:  Microvasc Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  293-305     Citation Subset:  IM    
Copyright Information:
Copyright 2001 Academic Press.
Department of Physiology, St. George's Hospital Medical School, London, SW17 ORE, United Kingdom.
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MeSH Terms
Actins / physiology*
Capillary Permeability / physiology
Cartilage, Articular / metabolism
Cytochalasin D / pharmacology*
Endothelium / cytology,  physiology
Extracellular Space / drug effects*,  physiology
Hindlimb / physiology
Knee Joint / blood supply*,  metabolism,  physiology*
Metabolic Clearance Rate / drug effects
Microcirculation / metabolism
Osmotic Pressure
Synovial Fluid / physiology*
Synovial Membrane / chemistry,  physiology*
gamma-Globulins / metabolism
Reg. No./Substance:
0/Actins; 0/gamma-Globulins; 22144-77-0/Cytochalasin D

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