Abstract
Background:
The mechanism of initial lymphatic filling and the role of cardiogenic tissue motion in promoting lymph formation and propulsion are at present still controversial issues, in particular when considering interstitial tissues whose fluid pressure is well below atmospheric. To elucidate these aspects, the micropuncture technique was used to record interstitial (Pint) and intralymphatic pressure (Plymph) simultaneously in the diaphragmatic lymphatic plexus draining the pleural cavity.
Methods and Results:
The diaphragmatic lymphatic network was identified in anesthetized rabbits and rats through fluorescent dextrans injected intrapleurally. All Plymph and Pint traces were pulsatile, oscillating either in-phase (33% of traces) or out-of-phase (67%) during cardiogenic swings. Plymph swept between –4.1 ± 0.9 (SE) mmHg and 3.5 ± 1.1 mmHg in rabbits, and between –5.1 ±1.0 mmHg and –2.7 ± 1.1 mmHg in rats. Pint oscillated between –0.8 ± 0.7 mmHg and 4.9 ± 0.7 mmHg in rabbits, and between –0.6 ± 0.8 mmHg and 0.9 ± 0.7 mmHg in rats.
Conclusions:
The data revealed a great functional complexity of the diaphragmatic lymphatic network and suggested that cardiogenic oscillations may play an important role in promoting lymph formation and propulsion from interstitial tissues with subatmospheric tissue pressure.
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