An observed pressor effect of the cerebellum during endotoxin shock in the dog

The current study investigates the possibility that the cerebellum may be involved in the regulation of mean arterial pressure (MAP) during endotoxin shock in the anesthetized dog. The effect of intravenously injected Escherichia coli endotoxin on MAP in the cerebellectomized dog was compared to that observed in the intact animal. Even though removal of the cerebellum did not significantly affect MAP in a control group, the cerebellectomized animal (unlike the intact animal) was unable to recover from the initial hypotension typically seen immediately following an intravenous endotoxin injection. Previous investigators have demonstrated that stimulation of fastigial nuclei in the cerebellum increases MAP via beta-adrenergic activation of the renin-angiotensin system. Captopril (SQ 14,225, an angiotensin I-converting enzyme inhibitor) was used to determine whether this system could be responsible for the maintenance of MAP during endotoxin shock. When continuously infused into the intact dog given endotoxin, captopril suppressed MAP to a level similar to that of the cerebellectomized group. A similar response pattern to endotoxin was also observed in animals with a spinal transection at C2.