Colonic inflammation increases Na+ currents in bladder sensory neurons.

The purpose of this study was to determine whether sensitization of pre-spinal afferents induced by colonic inflammation can affect the physiology of the urinary bladder. Tetrodotoxin-resistant (TTX-R) Na+ currents were examined in bladder sensory neurons after experimental colitis. Cell bodies of bladder dorsal root ganglia were retrogradely labeled and TTX-R Na+ currents were recorded in capsaicin-sensitive neurons. Colitis significantly enhanced response of bladder neurons to capsaicin by approximately 60% and the peak amplitude of TTX-R Na+ current by 51%. These results suggest that colonic inflammation leads to increased excitability of nociceptive bladder neurons.