The effect on blood pressure of removal of portions of the spinal cord in the thoracic region
Experimental biology and medicine
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: ( I ) 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
... sidered by Sherrington,' 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, lea\-ing 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' showed that sjTstcmic blood pressure fell on paralysis of the medulla oblongata some days after the transection of the spinal cord. I t remains to determine the actual effect upon systemic blood pressure of removal of portions of the spiiial cord below the level of trailsection after an interval of recovery. The spinal cord was transected under aseptic conditions a t varying levels from the second to the nivth thoracic, and the animal allowed to recovei. Some days afterward, the animal was again anesthetized and the systemic blood pressure recorded from a cannula in one carotid artery. In one cat, in which the level of transection was just below the fifth thoracic root, the mean level of blood pressure was 1 1 4 millimeters of mercury six days after the transection. The blood pressure remained at 78 Cats were used in our experiments. A mercury manometer was used.