Contractile stimuli in collecting lymph vessels
Hargens, A.R.; Zweifach, B.W.
American Journal of Physiology 233(1): H57-H65
1977
ISSN/ISBN: 0002-9513 PMID: 879337 Document Number: 117770
Contractility was investigated in collecting lymph vessels of rat and guinea pig mesentery. Lymphatic diameter and micropressure were simultaneously recorded under normal conditions and during micromanipulation of intralymphatic pressure. Spontaneous activity involved characteristic changes in intralymphatic pressure coincident with opening and closure of upstream and downstream valves. Contractions were irregular but still predictable by noting the trend of intraluminal pressure as it approached a threshold level. Mechanical obstruction upstream of lymph vessels reduced lymph pressure amplitude and spontaneous contraction frequency. Occlusion downstream increased intralymphatic pressure and contraction frequency. Microinjection or withdrawal of fluid caused contraction frequency to rise and fall, respectively. Contraction rate was not affected by the level of general anesthesia. Lymphatic wall tension, as calculated from pressure-radius variables, correlated well with contraction frequency, suggesting a myogenic origin for the contractile mechanism. However, lymphatic smooth muscle may be inherently unstable since some contractility persists despite an absence of pressure stimuli.