title: Traditional Chinese formula, lubricating gut pill, stimulates cAMP-dependent CI(−) secretion across rat distal colonic mucosa.
abstract: OBJECTIVE
  Lubricating gut pill (LGP), a traditional Chinese formula, had been conformed to improve the loperamide-induced rat constipation by stimulation of Cl(-) secretion, but its mechanism has not been fully explored. Thus, the purpose of this study was to identify the action sites of LGP-stimulated Cl(-) secretion across rat distal colonic mucosa.
  
  
  METHODS
  Rat distal colonic mucosa was mounted in Ussing chambers and short circuit current (I(SC)), apical Cl(-) current and basolateral K(+) current were recorded. Intracellular cyclic adenosine monophosphate (cAMP) content and protein kinase A (PKA) activity were determined with ELISA kit and the non-radioactive PepTag test, respectively.
  
  
  RESULTS
  LGP at 800μg/ml elicited a sustained increase in Cl(-) secretory response, which was inhibited by CFTR(inh)172, a cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor. Permeabilizing apical membrane with nystatin revealed that LGP-stimulated basolateral K(+) current was significantly inhibited by KCNQ1 K(+) channel inhibitor chromanol 293B. LGP-stimulated I(SC) was markedly reduced by pretreatment with cis-N-[2-phenylcyclopentyl]-azacyclotridec-1-en-2amine (MDL-12,330A) and N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), but not with inhibitors of Ca(2+)-dependent signaling pathway. Treatment of tissue with LGP resulted in an increase in intracellular cAMP level and the activation in protein kinase A. The E-prostanoid(4) (EP)(4) receptor antagonist L-161,982 completely eliminated LGP-induced response.
  
  
  CONCLUSIONS
  The results showed that LGP enhances Cl(-) and fluid secretion via prostanoid receptor signaling and also cAMP and protein kinase A pathway, subsequently triggering the activation of apical Cl(-) channels mostly CFTR and basolateral cAMP-dependent K(+) channel.
authors.affiliation: Institute of Chinese Materia Medica, Shanghai University of TCM, Shanghai 201203, China.
authors.forename: Dazheng
authors.initials: D
authors.lastname: Wu
authors.forename: Jiyan
authors.initials: J
authors.lastname: Zhou
authors.forename: Xinhong
authors.initials: X
authors.lastname: Wang
authors.forename: Bo
authors.initials: B
authors.lastname: Cui
authors.forename: Rui
authors.initials: R
authors.lastname: An
authors.forename: Hailian
authors.initials: H
authors.lastname: Shi
authors.forename: Jianye
authors.initials: J
authors.lastname: Yuan
authors.forename: Zhibi
authors.initials: Z
authors.lastname: Hu
mesh_terms: D000818:Animals; D000838:Anions / Q000378:metabolism; D001565:Benzoates; D002462:Cell Membrane; D065101:Chloride Channel Agonists; D002712:Chlorides / Q000378:metabolism*; D003106:Colon / Q000187:drug effects* / Q000378:metabolism; D003248:Constipation / Q000188:drug therapy / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004365:Drugs, Chinese Herbal / Q000494:pharmacology* / Q000627:therapeutic use; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D019684:Magnoliopsida; D008297:Male; D009761:Nystatin / Q000494:pharmacology; D010539:Permeability; D008517:Phytotherapy; D011188:Potassium / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D058309:Receptors, Prostaglandin E, EP4 Subtype / Q000037:antagonists & inhibitors; D053778:Thiazolidines
chemical_list: C482900:3-((3-trifluoromethyl)phenyl)-5-((3-carboxyphenyl)methylene)-2-thioxo-4-thiazolidinone; D000838:Anions; D001565:Benzoates; D065101:Chloride Channel Agonists; D002712:Chlorides; D004365:Drugs, Chinese Herbal; D026902:Potassium Channel Blockers; D058309:Receptors, Prostaglandin E, EP4 Subtype; D053778:Thiazolidines; D009761:Nystatin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D011188:Potassium