Sympathetic Vasodilator Outflow

Electrodes were implanted into the hypothalamus of dogs. Blood flow was measured in the femoral artery with an electromagnetic flow recorder. The circulation of the paw was cut off with a pneumatic cuff to ensure as pure muscle blood flow as possible. The electrodes were cemented into place when the sympathetic vasodilator area was reached as evident from the stimulatory response. Electrical activation of the sympathetic vasodilator area was repeated on the unanesthetized dogs. The circulatory responses and the behavior reactions were simultaneously recorded. As a final step, the animal was again anesthetized and the sympathetic vasodilator system activated to ensure that the electrodes were still in place. The dogs were then sacrificed and the hypothalamus removed for histological examination. (Author)