This study was designed to assess the effects of hemodynamic changes and cerebrospinal fluid dynamics on spinal cord function during experimental thoracic aortic occlusion. We investigated the effects of dopamine, sodium nitroprusside, and sodium thiopental in this model. Proximal and distal aortic pressures and cerebrospinal fluid pressure were measured during occlusion in 12 adult mongrel dogs under control conditions and during drug interventions. Spinal cord function was assessed by spinal somatosensory evoked potentials recorded during 3-minute intervals of reversible spinal cord ischemia. By multiple regression analysis, the degree of spinal cord ischemia was positively related to the cerebrospinal fluid pressure (p = 0.0092) and negatively related to the percent change in cerebrospinal fluid pressure (p = 0.028); there were no significant drug effects on cerebrospinal fluid pressure or on the degree of spinal cord ischemia. This study indicates that cerebrospinal fluid pressure is an important factor in determining the degree of spinal cord ischemia during aortic occlusion and suggests that measures to reduce cerebrospinal fluid pressure will mitigate the degree of spinal cord ischemia.