P2RX1 and colitis: Our in vivo data of increased purinergic signaling via P2X3 channels during acute TNBS-colitis are in line with previous in vitro findings of Wynn et al. [17] who showed that pelvic afferent nerve firing in response to colorectal distension was significantly increased in an isolated colon segment from rats with acute TNBS colitis and that this increase could be attenuated by the P2X receptor antagonist PPADS and the P2X1/P2X3 receptor antagonist TNP-ATP.