Fig. 2.

Multiple pumping behaviors predicted by simulations and observed in vivo (Movies S1–S4). (A) Lymphatic contractions in the mouse hindlimb model occur with a range of frequencies and amplitudes. High-amplitude, low-frequency strong pumping (blue), and lower-amplitude, higher-frequency weak pumping (red) are seen in the collecting lymphatic vessel feeding the popliteal lymph node in C57BL/6 mice (plots are from intravital microscopy of the same mouse at different times). (B) In addition to strong and weak pumping, vessels can dilate and minimize contractions (black line) in response to inflammation induced by oxazolone skin painting. (C) Strong (blue) and weak pumping (red) are reproduced in the simulations by varying the axial pressure gradient. (D) To simulate the multiple behaviors during inflammation, only the baseline diameters and pressure gradient were adjusted. The large-diameter mode with no contractions can be reproduced in the simulations by imposing a driving axial pressure gradient, which induces shear stress, producing NO and maintaining relaxation (black).