MEASUREMENT OF FLOW CHARACTERISTICS DURING INDIVIDUAL CONTRACTIONS IN BOVINE MESENTERIC LYMPHATIC VESSELS

Abstract

We developed a novel technique for measuring flow characteristics during individualcontractions in lymph vessels. Bovine mesenteric lymph vessel segments (n=15) were mounted inorgan baths and allowed to equilibrate for 1 hr. Transmural pressure was subsequentlyincreased by 2 cm H2O increments at 15 min intervals and vessel outputs were collected duringthe final 10 min of each period and measured. Flow also was continuously recorded with an inline Doppler transducer connected to a flow analyzer, and flow characteristics were analyzed. The two methods of flow measurement correlated well (r2 = 0.92). Mean flow increasedwith increasing transmural pressure and reached a maximum of 0.5 ± 0.1 ml/min at atransmural pressure of 8 cm H2O. The rate of spontaneous contractions, the peak flow during acontraction-induced wave, and the total volume of flow during a wave also increased withincreasing transmural pressure and reached maximums of 12.4 ± 1.0 min-1, 8.2 ± 1.6 ml/min,and 0.21 ± 0.06 ml, respectively. Wave duration changed little in response to changes intransmural pressure.Continuous in-line flow measurement is an accurate technique for assessing flowcharacteristics during individual contractions in lymph vessels in vitro. Transmural pressureregulates flow by influencing spontaneous contraction frequency and total and peak flows duringcontraction-induced waves.