Cardiovascular Response to Experimental Spinal Cord Trauma in Cats

ABSTRACT

The study was undertaken to determine the cardiovascular response to spinal cord trauma and to determine the autonomic mechanisms involved. The arterial pressure was recorded in anesthetized cats during spinal cord trauma of 50gm-cm at T4-T6 levels. The spinal cord trauma resulted in a sudden increase of systemic blood pressure from a control level of 92mmHg to 140mmHg, an increase of 52%, at 45 seconds. This initial hypertensive plase lasted approximately 3 to 4 minutes, and then was followed by a hypotensive phase. 2) This pressor response was mediated by an beta-adrenergic blocking agent. 3) During the hypertensive phase, the pulse pressure was increased while the heart rate was decreased, The pulse pressure and the heart rate changed symmetrically, showing the maximal elevation and minimal decrease at 20 seconds, respectively. These results suggest that the alternations in blood pressure that follow the spinal cord trauma are most likely related to alternations of peripheral arteriolar resistance and venous return of blood to the heart.