Adrenal Medullary Secretion in Response to Insulin Hypoglycemia in Dogs with Transection of the Spinal Cord

Experiments were done in dogs anesthetized with Nembutal. Adrenal venous blood was collected and analyzed for adrenaline and noradrenaline by the fluori-method. In intact dogs insulin hypoglycemia was accompanied by a marked metric increase in adrenal medullary secretion. In dogs whose spinal cord was transected at the level of the lowest cervical segment one or 4-7 days previously, the adrenal medullary secretion was increased significantly by insulin hypogly-cemia. The magnitude of increase in these dogs was, however, far smaller than that in intact ones. Section of the splanchnic nerves abolished almost com-pletely the rise in adrenal medullary secretion of the ipsilateral gland in response to insulin hypoglycemia. It is concluded that although the thoracic (or thoracico-lumbar) spinal center is sensitive to hypoglycemia and plays some role in promoting adrenal medullary secretion, the upper center situated above the level of spinal cord transection plays a more essential role for the adrenal medullary response to hypoglycemia.