Viscerovisceral convergence of urinary bladder and colorectal inputs to lumbosacral spinal neurons in rats

Extracellular potentials of single L6–S2 spinal neurons were recorded in pentobarbital anesthetized male rats. The urinary bladder was catheterized through the fundus and filled with warm saline for urinary bladder distension (UBD, 0.5–2.0 ml, 20 s). Colorectal distension (CRD) was produced by distending a latex balloon with air (20–80 mmHg, 20 s). Of 171 deeper neurons examined for responses to UBD and CRD, 49 (29%) neurons responded to both UBD and CRD; whereas 6/42 (14%) superficial neurons (depth