Sympathetic stimulation causes increased output of lymphocytes from the popliteal node in anaesthetized sheep.

Stimulation of the lumbar sympathetic chain at a frequency of 4 Hz caused a threefold increase in the lymphocyte output in efferent lymph from the popliteal node in anaesthetized sheep. The increase was accounted for by a rise in both lymph flow and lymphocyte count. Intra-arterial infusion of phentolamine (10 micrograms kg-1 min-1) abolished the nerve-mediated increases in flow and cell count.