title: Rhein stimulates electrogenic chloride secretion by activation of submucosal neurons in guinea pig colon.
abstract: Conventional flux chamber methods were applied to investigate the mode of action of rhein, an active metabolite derived from colonic microbial fermentation of the naturally occurring sennoside laxatives, in muscle-stripped segments of guinea pig colon. Mucosal or serosal application of rhein (10 nmol/1 to 0.5 mmol/l) resulted in a dose-dependent increase in short-circuit current (Isc) that was superimposed by irregular fluctuations in Isc. The response to electrical field stimulation was increased. The rhein-evoked increase in Isc was reduced by serosal addition of 50 mumol/l bumetanide, 1 mumol/l tetrodotoxin, 1 mumol/l atropine and 10 mumol/l piroxicam but not 100 mumol/l hexamethonium, 1 mumol/l ICS 205 930 or 10 mumol/l cimetidine. The study suggests that rhein activates chloride secretion by excitation of submucosal neurons and release of acetylcholine and endogenous prostaglandins, but not by release of histamine or serotonin.
authors.affiliation: Department of Gastroenterology, Heinrich Heine University of Düsseldorf, FRG.
authors.forename: T
authors.initials: T
authors.lastname: Frieling
authors.forename: C
authors.initials: C
authors.lastname: Rupprecht
authors.forename: M
authors.initials: M
authors.lastname: Schemann
mesh_terms: D000109:Acetylcholine / Q000502:physiology; D000818:Animals; D000880:Anthraquinones / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001692:Biological Transport; D018118:Chloride Channels / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism*; D003106:Colon / Q000187:drug effects* / Q000294:innervation; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D017615:Enteric Nervous System / Q000187:drug effects* / Q000502:physiology; D006168:Guinea Pigs; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000502:physiology; D011453:Prostaglandins / Q000502:physiology
chemical_list: D000880:Anthraquinones; D018118:Chloride Channels; D002712:Chlorides; D011453:Prostaglandins; D000109:Acetylcholine; C020491:rhein