The effect on blood pressure of removal of portions of the spinal cord in the thoracic region

The argument for the functional independence of the peripheral ganglia of the sympathetic nervous system has rested largely on the experiments of Goltz, who removed portions of the thoracic region of the spinal cord after previous transection. Two conditions should be sharply distinguished here: (1) when the transection of the spinal cord is in the lower cervical region above the level of outflow of the sympathetic fibers from the thoracic roots. This condition has been considered by Sherrington, 1 who showed that the blood pressure fell markedly on actual destruction of the spinal cord 300 days after the first transection. (2) When the spinal cord is transected in the upper thoracic region, leaving a functional connection of the medulla oblongata with the periphery through a few rami communicantes of the sympathetic system emerging with the roots of the upper thoracic nerves. Miss Yates 2 showed that systemic blood pressure fell on paralysis of the medulla oblongata some days after the transection of the spinal cord. It remains to determine the actual effect upon systemic blood pressure of removal of portions of the spinal cord below the level of transection after an interval of recovery.

Cats were used in our experiments. The spinal cord was transected under aseptic conditions at varying levels from the second to the ninth thoracic, and the animal allowed to recoyel. Some days afterward, the animal was again anesthetized and the systemic blood pressilre recorded from a cannula in one carotid artery. A mercury manometer was used. In one cal, in which the level of transection was just below the fifth thoracic root, the mean level of blood pressure was 114 millimeters of mercury six days after the transection. The blood pressure remained at 78 millimeters after removal of a section of the spinal cord eight centimeters long below the level of the first transection.