Involvement of central vs. peripheral mechanisms in mediating sympathoadrenal activation in endotoxic rats

central vs. peripheral mechanisms in mediating sympathoadre-nal activation in endotoxic rats. Am. J. Physiol. 265 (Regulatory Integrative Comp. Physiol. 34): R683-R688, 1993.-The contri-bution of central vs. peripheral mechanisms in mediating in-creases in plasma norepinephrine (NE) and epinephrine (Epi) during endotoxicosis were studied. Plasma catecholamine re-sponses after endotoxin were assessed in conscious animals and in animals without central regulatory mechanisms (pithed rats). In conscious rats, endotoxin (1.5 mg/kg iv) induced a marked elevation in plasma NE after 90 min (3-fold), but elevations were not seen in pithed rats. Endotoxin also induced a profound increase (12- to 13-fold) in plasma Epi in conscious rats, but increases were less (2- to 3-fold) and delayed in pithed rats. These results suggest hat central mechanisms are essential in plasma NE response to endotoxic challenge, whereas plasm