Contractile response in isolated human groin lymphatics.

Lymphatics from the human superficial groin removed at operation in 21 patients (one with lymphedema) were examined in vitro. Histochemically no nerves were identified with either specific catecholamine fluorescence or immunoreactivity to tyrosine hydroxylase or dopamine beta-hydroxylase. Ring preparations of the lymphatics were mounted in tissue baths and isometric induced contractions were recorded after administration of K+ (124 mM), acetylcholine, selected amines and prostanoids. Noradrenaline (NA), adrenaline, dopamine, and acetylcholine had no or only weak contractile effects. In some segments, serotonin induced contractions. Prostaglandin E2 showed no contractile effect and prostaglandin F2 alpha induced contraction in most of the tested lymphatics. The prostaglandin-endoperoxide analogue U44069 uniformly elicited marked concentration-dependent contraction. In the lymphatic segment from the patient with lymphedema, a slightly greater contractile response to NA and serotonin was observed. The results overall suggest an absence of sympathetic innervation and contraction-mediating alpha adrenergic receptors in human superficial groin lymphatics, and support that certain prostanoids may be important regulators of human lymphatic contractility.