THE EFFECT OF LUMBAR SYMPATHETIC STIMULATION ON THE VASCULATURE OF BONE

1 The nutrient artery to the tibia of anaesthetized dogs was perfused at a constant rate by blood from the femoral artery and the perfusion pressure in the artery, the intramedullary pressure of the bone and the pressure in the nutrient vein recorded. 2 Low frequency stimulation (1 to 5 Hz) of the lumbar sympathetic chain always increased the perfusion pressure but the intramedullary pressure sometimes increased, sometimes decreased and sometimes remained unchanged. 3 The α‐adrenoceptor blocking agents, phentolamine (1 mg/kg i.v.) and dihydroergotamine (0.5 mg/kg i.v.) reduced or abolished these effects whereas the β‐adrenoceptor blocking agent, propranolol (1 mg/kg i.v.) did not modify them. 4 The nutrient vein end pressure did not differ significantly from the intramedullary pressure and underwent similar variations during stimulation of the lumbar sympathetic chain.