Abstract
It has been reported that unilateral, noxious somatic stimulation of the elbow joint increases cerebral blood flow (CBF) over broad, bilateral areas of the cerebral cortices in anesthetized cats, in association with an increase in systemic arterial pressure (Exp. Brain Res., 1998; 118:439). The present study was designed to re-examine this phenomenon in cats that had their spinal cord transected at the first thoracic segment, in order to eliminate the confounding effects of elevated systemic blood pressure on CBF. Noxious cutaneous pinching of a forepaw or noxious inward and outward rotation of an elbow joint for 20-30s resulted in a significant increase in CBF in cats spinalized at the T1 level. Specifically, blood flow increased in the forelimb area of primary somatosensory cortex contralateral to the side stimulated; the systemic blood pressure in these animals remained unchanged. These data suggest that the increases in CBF in the other brain regions described previously in somatically stimulated cats were indirectly due to the increased blood pressure seen in those animals. Our results are discussed in the context of data reported in anesthetized rats whose spinal cord was transected at the upper thoracic level. [J Physiol Sci. 2008;58 Suppl:S98]
