H. M. Wei, A. K. Sinha and H. R. Weiss
Department of Anesthesia, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854-5635.
This study evaluated the hypothesis that the peripheral sympathetic nervous
system is one of the factors increasing the heterogeneity of venous O2
saturation in selective brain regions. Regional cerebral blood flow and O2
saturation were determined in the anterior cortex, posterior cortex, and
medulla of either sham-operated or bilaterally sympathectomized Long-Evans
rats. Cerebral venous O2 saturations, indicating the balance between local
O2 supply and consumption, were found to be significantly more
heterogeneous in the sham-operated group. In the anterior cortex, the
coefficient of variation [100(SD/mean)] for the sham-operated animals was
22.4%.
Sympathectomy significantly reduced this heterogeneity in the anterior cortex through a reduction in the number of low O2 saturation veins (coefficient of variation 11.7%). Blood flow and O2 consumption in
the anterior cortex were not different between groups. The effects of
sympathectomy in the posterior cortex were similar to those in the anterior
cortex. However, sympathectomy did not alter any measured variables in the
medulla. Thus, bilateral superior cervical ganglionectomy reduced the
heterogeneity of cerebrocortical venous O2 saturation by reducing the
number of low O2 saturation veins in the rostral part of the brain.