Simultaneous measurement of pressure in the interstitium and the terminal lymphatics of the cat mesentery.

Abstract

Simultaneous measurements of the pressure in terminal lymphatics and interstitial tissue were made in the exteriorized cat mesentery superfused with either physiological salt solution (Krebs solution) or a water-immiscible fluorocarbon, FC-80. The pressures within individual terminal lymphatics were measured using glass micropipettes attached to a servo pressure-measuring system. Tissue pressures were recorded using saline-filled cotton-wool wicks. Mean pressures recorded in the terminal lymphatics of the Krebs-superfused mesentery were slightly above atmospheric (+ 0.2 mmHg, n = 45), while those recorded in the FC-80-superfused mesentery were slightly below atmospheric (- 0.2 mmHg, n = 46). Tissue pressures were also slightly subatmospheric in the in situ mesentery, and the recently exposed tissue. Continuous superfusion with Krebs solution caused the tissue pressure to rise to atmospheric pressure or above; with FC-80-superfusion the tissue pressure also rose, but never to above atmospheric pressure. Isolated strips of mesentery immersed in Krebs solution of different concentrations gained weight, but when immersed in FC-80 no change in weight was detected. The interstitial gel of the mesentery is normally unsaturated and superfusion with Krebs solution leads to tissue edema. This tendency is less marked in FC-80-superfused preparations. Possible mechanisms for lymph formation and propulsion are discussed.