Lymphatic Innervation

Abstract

Bovine mesenteric lymphatic vessels have nerves in their walls which in response to field stimulation cause an increase in freqency of spontaneous lymphatic contractions and this could be blocked by α-antagonists. When vessels were loaded with [³H]-noradrenaline, ³H-effiux was increased in response to field stimulation and this was potentiated by α₂-antagonists and depressed by α₂-agonists. Electrical activity in these vessels consisted of a single action potential which preceded each contraction. Mean resting potential was –61 mV ± 5.7 (SD). Stimulation of postsynaptic α-receptors caused a depolarization accompanied by a decrease in membrane conductance while β-receptor stimulation had the opposite effect. Lymphatic noradrenergic nerves appear to have a role in the living animal since stimulation of the sympathetic chain in anaesthetized sheep increased popliteal efferent lymph flow and this could be blocked by α-adrenergic blockers.