Cerebral blood flow and oxygen consumption in the rat brain after lesions of the noradrenergic locus coeruleus system.

The effect of lesions of the locus coeruleus neuron system on cerebral metabolic rate for oxygen (CMRO2) and blood flow (CBF) was evaluated in paralyzed and mechanically ventilated rats, using a 133xenon modification of the Kety-Schmidt inert gas technique. Bilateral electrothermic lesions of its ascending bundle caused no significant change in CBF or CMRO2. The 6-hydroxydopamine lesions did not influence the CBF and CMRO2 responses to hypercapnia and hypoxia. It is concluded that the locus coeruleus does not exert any resting tone on CBF and CMRO2 and that no influence on the CBF and CMRO2 responses to hypercapnia and hypoxia is mediated via its ascending projections.