Spinal root pathway of the adrenal medullary secretory nerve fibers in the dog.

Abstract

In dogs anesthetized with sodium pentobarbital, adrenal venous blood was collected and analyzed for adrenaline and noradrenaline fluorometrically. Electrical stimulation of the ventral spinal root from the fifth thoracic (T5) to the first lumbar (L1) segments produced a significant increase in adrenal medullary secretion. On the contrary, stimulation of the dorsal spinal root had no effect on adrenal medullary secretion. Unilateral section of the ventral spinal roots from T5 to L1 abolished an increased adrenal medullary secretion of the ipsilateral adrenal gland in response to insulin-induced hypoglycemia. Section of the dorsal spinal roots had no effect. It is concluded that the adrenal medullary secretory nerve fibers in dogs pass through the ventral spinal roots at the levels of T5-L1.