Huqi San-Evoked Rat Colonic Anion Secretion through Increasing CFTR Expression

Huqi San (HQS) is a Chinese herbal preparation of eight medicinal herbs that promote diuresis, detoxification, blood circulation, and cholestasis. Defects in transporter expression and function can cause cholestasis and jaundice. However, the mechanism of the cholestasis underlying HQS effects, especially on the gastrointestinal tract ion secretion, has not been elucidated. Real-time RT-PCR and Western blotting were used to study the expression and localization of cystic fibrosis transmembrane conductance regulator (CFTR) and α-ENaC in rat alimentary tract, and then the effect of HQS on the ion transport in rat distal colon mucosa was investigated using the short-circuit current (I SC) technique. The results showed that pretreatment with HQS significantly enhanced mRNA transcripts and protein content of CFTR in liver and distal colon but not α-ENaC in alimentary organs. HQS increases I SC and decreases the transepithelial resistance. Pretreatment with epithelial Na(+) channel blocker did not affect the I SC responses elicited by HQS, but removal of extracellular Cl(-) or pretreatment with Cl(-) channel or Na(+)-K(+)-2Cl(-) cotransporter blocker inhibited HQS-elicited I SC responses. These findings demonstrated that HQS, RA, and RP can stimulate Cl(-) secretion in the distal colon by increasing the mRNA transcripts and protein content of CFTR in liver and distal colon.