The purpose of this study in anesthetized rats was to determine the effects of stimulating cardiopulmonary sympathetic afferents (CPSA) and vagal afferents on C1-C2 descending propriospinal neurons. We hypothesized that inhibition of spinal sensory neurons produced by CPSA or vagus activation might relay in C1-C2 spinal segments. Extracellular action potentials were recorded from 73 C1-C2 neurons whose axons were antidromically activated in lumbar segments. CPSA input excited 22 cells, inhibited two cells and excited/inhibited one cell, whereas vagal input excited eight cells and inhibited two cells. Results are consistent with the hypothesis that CPSA input can be processed in C1-C2 segments to produce neural modulation in distant spinal segments.