Role of hyaluronan chain length in buffering interstitial flow across synovium in rabbits
Synovial fluid drains out of joints through an interstitial pathway. Hyaluronan, the major polysaccharide of synovial fluid, attenuates this fluid drainage; it creates a graded opposition to outflow that increases with pressure (outflow âbufferingâ). This has been attributed to size-related mole...
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Published in | The Journal of physiology Vol. 526; no. 2; pp. 425 - 434 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
The Physiological Society
15.07.2000
Blackwell Science Ltd Blackwell Science Inc |
Subjects | |
Online Access | Get full text |
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Summary: | Synovial fluid drains out of joints through an interstitial pathway. Hyaluronan, the major polysaccharide of synovial fluid,
attenuates this fluid drainage; it creates a graded opposition to outflow that increases with pressure (outflow âbufferingâ).
This has been attributed to size-related molecular reflection at the interstitium-fluid interface. Chain length is reduced
in inflammatory arthritis. We therefore investigated the dependence of outflow buffering on hyaluronan chain length.
Hyaluronan molecules of mean molecular mass â2200, 530, 300 and 90 kDa and concentration 3.6 mg ml â1 were infused into the knees of anaesthetized rabbits, with Ringer solution as control in the contralateral joint. Trans-synovial
drainage rate was recorded at known joint pressures. Pressure was raised in steps every 30â60 min (range 2â24 cmH 2 O).
With hyaluronan-90 and hyaluronan-300 the fluid drainage rate was reduced relative to Ringer solution ( P < 0.001, ANOVA) but increased steeply with pressure. The opposition to outflow, defined as the pressure required to drive
unit outflow, did not increase with pressure, i.e. there was no outflow buffering.
With hyaluronan-530 and hyaluronan-2000 the fluid drainage rate became relatively insensitive to pressure, causing a near
plateau of flow. Opposition to outflow increased markedly with pressure, by up to 3.3 times over the explored pressures.
Hyaluronan concentration in the joint cavity increased over the drainage period, indicating partial reflection of hyaluronan
by synovial interstitium. Reflected fractions were 0.12, 0.33, 0.25 and 0.79 for hyaluronan-90, -300, -530 and -2200, respectively.
Thus the flow-buffering effect of hyaluronan depended on chain length, and shortening the chains reduced the degree of molecular
reflection. The latter should reduce the concentration polarization at the tissue interface, and hence the local osmotic pressure
opposing fluid drainage. In rheumatoid arthritis the reduced chain length will facilitate the escape of hyaluronan and fluid. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1111/j.1469-7793.2000.00425.x |