RESUMEN
Single unit activity were recorded from 157 dorsal horn neurons in the spinal rats by stimulation of left surat nerves. Stretching urinary bladder were performed after the neurons were identified by somatic afferents. 32 out of the 157 could also be activated by stretching urinary bladders. These recorded dorsal horn neurons which responded to both somatic and visceral inputs are called somatovisceral convergent neurons (SVCN). The afferent visceral fibers were N group according to conductive velocity in our experiment. It has been shown that C-fiber component in 9 WDR neurons were incresed by stimulating the left sural nerves after stretching urinary bladders. 15 spontaneous- discharge WDR neurons were recorded and 13 out of them were excited, meanwhile, 2 out of them were inhibited after urinary bladders were stretched. The study provides the new data for the convergence from the somatic and visceral afferents in the dorsal horn of spinal cord and supplies the first evidence for central mecha nism of visceral referred pain.