Sympathetic Control of the Circulation in the Hind Leg of the Dog

¹ From the Department of Surgery, Western Reserve University School of Medicine, City Hospital of Cleveland, Cleveland, Ohio

Experiments were undertaken to test the effects of ablation or stimulation of the lumbar sympathetic nerves upon the circulation of the skin and skeletal muscle in the hind leg of the dog. Insulation of the skin was abolished by wetting the fur. Insulation of the muscles was abolished by incising and reflecting the skin which covered the part to be studied. As indices of circulation, the temperatures of skin and muscle were recorded by means of thermocouples, and the tensions of oxygen in skin and muscle were recorded as measured by the polarograph. Most of the experiments were conducted in a room in which temperature and humidity were controlled. After chronic sympathetic denervation, the temperature and oxygen tension of skeletal muscle were lower than in the contralateral control. Those of the skin were higher than in the control side. Electric stimulation of the lumbar sympathetic trunk consistently caused a rise in the tension of oxygen in muscle and a fall in skin. This was not attributable to hematometakinesia but to active vasodilation in muscle. Changes in temperature were always in the same direction as changes in oxygen tension.