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Hyaluronan efflux from canine lung with increased hydrostatic pressure and saline loading
M I Townsley1, R K Reed, M Ishibashi
1Department of Physiology, University of South Alabama, Mobile 36688.
American Journal of Respiratory and Critical Care Medicine
|December 1, 1994
Summary
Lung lymphatic washout of hyaluronan increases with elevated lymph flow, challenging the idea that it depletes lung hyaluronan. This suggests rapid mobilization of lung hyaluronan is possible.
Area of Science:
- Pulmonary Physiology
- Lymphatic System Dynamics
- Biochemistry
Background:
- The role of lymphatic hyaluronan (HA) washout in lung hydration and albumin exclusion remains unclear.
- Previous hypotheses suggest HA depletion contributes to altered lung permeability.
- Direct testing of HA lymphatic transport during lung hydration is needed.
Purpose of the Study:
- To investigate the direct relationship between lung lymphatic flow and hyaluronan transport.
- To test the hypothesis that lymphatic washout depletes lung interstitial hyaluronan.
- To quantify lung hyaluronan mobilization under conditions of increased lymph flow.
Main Methods:
- Anesthetized, ventilated dogs underwent cannulation of a prenodal lung lymphatic.
- Measurements included lymph flow and hyaluronan concentration under varying pleural pressure (Pla) or following saline infusion.
- Lung hyaluronan content was assessed post-experiment in a subset of animals.
Main Results:
- Increased lymph flow consistently elevated lymph hyaluronan concentration and flux (p < 0.05).
- Lung hyaluronan content did not significantly decrease after saline infusion, despite increased lymphatic transport.
- Daily lung hyaluronan turnover via lymph increased from 2-3% at baseline to 54% after saline infusion.
Conclusions:
- Lymphatic washout of hyaluronan increases with elevated lymph flow, but does not deplete interstitial lung hyaluronan.
- Lung hyaluronan is rapidly mobilized via lymphatic pathways when lymph flow is increased.
- The findings challenge the hypothesis that lymphatic hyaluronan depletion underlies altered lung permeability during hydration.
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