title: Stimulation of chloride secretion by baicalein in isolated rat distal colon.
abstract: The effect of baicalein on mucosal ion transport in the rat distal colon was investigated in Ussing chambers. Mucosal addition of baicalein (1-100 microM) elicited a concentration-dependent short-circuit current (I(sc)) response. The increase in I(sc) was mainly due to Cl(-) secretion. The presence of mucosal indomethacin (10 microM) significantly reduced both the basal and subsequent baicalein-evoked I(sc) responses. The baicalein-induced I(sc) were inhibited by mucosal application of diphenylamine-2-carboxylic acid (100 microM) and glibenclamide (500 microM) and basolateral application of chromanol 293B (30 microM), a blocker of K(v)LQT1 channels and Ba(2+) ions (5 mM). Treatment of the colonic mucosa with baicalein elicited a threefold increase in cAMP production. Pretreating the colonic mucosa with carbachol (100 microM, serosal) but not thapsigargin (1 microM, both sides) abolished the baicalein-induced I(sc). Addition of baicalein subsequent to forskolin induced a further increase in I(sc). These results indicate that the baicalein evoked Cl(-) secretion across rat colonic mucosa, possibly via a cAMP-dependent pathway. However, the action of baicalein cannot be solely explained by its cAMP-elevating effect. Baicalein may stimulate Cl(-) secretion via a cAMP-independent pathway or have a direct effect on cystic fibrosis transmembrane conductance regulator.
authors.affiliation: Department of Physiology, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China. whko@cuhk.edu.hk
authors.forename: W H
authors.initials: WH
authors.lastname: Ko
authors.forename: V W Y
authors.initials: VW
authors.lastname: Law
authors.forename: W C Y
authors.initials: WC
authors.lastname: Yip
authors.forename: G G L
authors.initials: GG
authors.lastname: Yue
authors.forename: C W
authors.initials: CW
authors.lastname: Lau
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D003106:Colon / Q000187:drug effects* / Q000378:metabolism*; D000242:Cyclic AMP / Q000096:biosynthesis; D015232:Dinoprostone / Q000494:pharmacology; D004553:Electric Conductivity; D005260:Female; D044950:Flavanones; D005419:Flavonoids / Q000494:pharmacology*; D007213:Indomethacin / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000187:drug effects; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D026902:Potassium Channel Blockers; D051381:Rats; D017207:Rats, Sprague-Dawley; D013779:Tetrodotoxin / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D002712:Chlorides; D044950:Flavanones; D005419:Flavonoids; D018727:Muscarinic Antagonists; D026902:Potassium Channel Blockers; D005576:Colforsin; D013779:Tetrodotoxin; C006680:baicalein; D019284:Thapsigargin; D001285:Atropine; D000584:Amiloride; D002217:Carbachol; D000242:Cyclic AMP; D015232:Dinoprostone; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine; D007213:Indomethacin