Distension pressure on subserosal and mesenteric lymph pressures of rat jejunum

Lymph pressure (Pl) in the subserosal lymphatics and mesenteric lymphatics was determined in the jejunum at various intraluminal distension pressures (DP). Pl in the subserosal lymphatics was approximately equal to DP, in the range of 3-100 mmHg, whether the intestine was in the basal state or during water absorption. At a DP of 0 mmHg, Pl was 1.5 +/- 0.1 mmHg. When DP was 3, 10, 20, 40, 70, or 100 mmHg, Pl was 2.9 +/- 0.2, 11 +/- 1, 23 +/- 1, 43 +/- 1, 71 +/- 2, or 102 +/- 2 mmHg, respectively. From these findings and other considerations it is inferred that Pl in the subserosal lymphatics could be similar to the tissue fluid pressure, which is apparently determined by DP due to compression of the intestinal wall. On the other hand, Pl in the mesenteric lymphatics was not affected by DP at all. When DP was in the range of 0-70 mmHg with free flow of lymph, mean Pl was 6-8 mmHg, and it was 23-28 mmHg during lymphatic obstruction. During pressure measurement, rhythmical contractions of these lymphatics occurred, which may be mainly responsible for the increase of Pl and propulsion of lymph as well.