Regulating Effect Of Tongxie-Yaofang On Colonic Epithelial Secretion Via Cl- And Hco3- Channel

AIMTo investigate the pharmacological effect of TongXie-YaoFang (TXYF) formula, a Chinese herbal formula, on Diarrhea-predominant irritable bowel syndrome (D-IBS) rats.METHODSIn a neonatal maternal separation plus restraint stress (NMS + RS) model of D-IBS, male Sprague Dawley rats were randomly divided into two groups (NMS + RS group and TXYF-formula group) with no handlings were used as controls (NH group). Starting from postnatal day 60, rats in TXYF-formula group were administered TXYF-formula (4.92 g/100 g bodyweight) orally twice a day for 14 consecutive days while NH group and NMS + RS group were given distilled water. Using short-circuit current technology, we observed 5-HT-induced changes of current across ion channels, such as cystic fibrosis transmembrane conductance regulator (CFTR) Cl-channel, epithelial Na+ channel (ENaC), Ca2+-dependent Cl-channel (CACC), Na+-K+-2Cl-co-transporter (NKCC), and Na+-HCO3- co-transporter (NBC), in the colonic epithelium of three groups after exposure to drugs and specific blockers with a Power Lab System (AD Instruments International).RESULTSUnder basal conditions, the changes of short-circuit current (Delta Isc, mu A/cm(2)) induced by 5-HT were similar in NH group and TXYF-formula group, and both higher than NMS + RS group (70.86 mu A/cm(2) +/- 12.32 mu A/cm(2), 67.67 mu A/cm(2) +/- 11.68 mu A/cm(2) vs 38.8 mu A/cm(2) +/- 7.25 mu A/cm(2), P < 0.01, respectively). When CACC was blocked by 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid, 5-HT-induced Delta Isc was smaller in NMS + RS group than in NH group and TXYF-formula group, respectively (48.41 mu A/cm(2) +/- 13.15 mu A/cm(2) vs 74.62 mu A/cm(2) +/- 10.73 mu A/cm(2), 69.22 mu A/cm(2) +/- 11.7 mu A/cm(2), P < 0.05, respectively). The similar result could be obtained when ENaC was blocked by Amiloride (44.69 mu A/cm(2) +/- 12.58 mu A/cm(2) vs 62.05 mu A/cm(2) +/- 11.26 mu A/cm(2), 62.11 mu A/cm(2) +/- 12.01 mu A/cm(2), P < 0.05, respectively). However, when CFTR Cl-channel was blocked by 1,1-dimethyl piperidinium chloride (DPC), 5-HT-induced.Isc did not significantly differ in three groups (42.28 mu A/cm(2) +/- 10.61 mu A/cm(2) vs 51.48 mu A/cm(2) +/- 6.56 mu A/cm(2) vs 47.75 mu A/cm(2) +/- 7.99 mu A/cm(2), P > 0.05, respectively). The similar results could also be obtained in three groups when NBC and NKCC were respectively blocked by their blockers.CONCLUSIONTXYF-formula can regulate the Cl- and HCO3- secretion of colonic mucosa via CFTR Cl-channel, Cl-/HCO3- exchanger, NBC and NKCC co-transporters.