Heparin inhibits contraction of smooth muscle cells in lymphatic vessels.

Heparin in concentrations of 10-50 U/ml produced a decrease in the amplitude and frequency of phasic contractions of smooth muscle cells of bovine mesenteric lymphatic vessels. Vascular wall tension was reduced under these conditions. The endothelium-dependent effect of heparin is realized via an increase in the production of nitric oxide by endothelial cells and, to a lesser degree, via the stimulation of prostacyclin synthesis.