Primary function within an organ is flow regulation, thereby determining oxygen delivery and the washout of metabolic by-products. Regulate, in part, capillary hydrostatic pressure and therefore influence capillary fluid exchange . Fluid and macromolecular exchange occur most prominently at venular junctions. Sympathetic innervation of larger venules can alter venular tone which plays a role in regulating capillary hydrostatic pressure. Larger lymphatics also have smooth muscle cells.
Sympathetic nerves can modulate vasomotion and cause contraction.