Barakol Extracted from Cassia siamea Stimulates Chloride Secretion in Rat Colon

Abstract

Barakol is a purified extract of Cassia siamea, a plant that has been used as a laxative in traditional medicine. In this study, the effect of barakol on anion transport across the rat colon epithelium was investigated. Colonic epithelium was mounted in Ussing chambers and bathed with Ringer's solution. Addition of 1 mM barakol to the basolateral solution produced a slow increase in short-circuit current (Isc) in proximal colon and distal colon by 24.5 Ϯ 2.2 and 24.2 Ϯ 1.4 A/cm 2 , respectively. Barakol increased Isc in a concentration-dependent manner with an EC 50 value of 0.4 mM. The barakol-stimulated increase in Isc was inhibited by subsequent treatment with 500 M diphenylamine-2-carboxylic acid or 400 M glibenclamide added to the apical solution and 200 M bumetanide added to the basolateral solution. Pretreatment of the tissues with 200 M bumetanide, but not 10 M amiloride, completely abolished the barakol-increased Isc. Ion substitution experiments showed an inhibition of barakol-stimulated Isc in chloride-free solution but not in bicarbonate-free solution. In addition, pretreatment of tissues with 10 M tetrodotoxin or 10 M indomethacin, but not 1 M atropine or 10 M hexamethonium, partially inhibited the Isc response by barakol. The present results demonstrated the stimulatory effect of barakol on the bumetanide-sensitive chloride secretion in rat colon. The effect of barakol was partly mediated by the stimulation of submucosal nerves and through the release of cyclooxygenase metabolites. These findings thus provide an explanation for the underlying mechanism of barakol as a secretagogue in mammalian colon.

Laxative activities of Mareya micrantha (Benth.) Müll. Arg. (Euphorbiaceae) leaf aqueous extract in rats

“…Most of the naturally laxative exert their effects on the colonic epithelium by stimulating Cl - secretion and/or inhibiting Na + absorption, resulting in an accumulation of fluid and subsequent increased colonic motility [25]. …”

Segregation of Na/H exchanger-3 and Cl/HCO3exchanger SLC26A3 (DRA) in rodent cecum and colon

“…The functional segments demarcated by our study appear to have two easily identifiable anatomical features. First, the proximal portion of the colon that expresses abundant NHE3 but scant DRA (0 -20% length) roughly corresponds to the segment that displays serosal palmleaf striations (21,31,55). Second, the portion of the rodent distal colon that is deficient in NHE3 (60 -100% colon length in rats and 75-100% in mice) is largely comprised of the extraperitoneal segment that extends from the pelvic brim to the anus; previous studies have indicated that this segment, sometimes called the rectum (30), uniquely exhibits aldosterone-stimulated electrogenic Na ϩ absorption and a weaker Cl Ϫ secretory capacity (7,30,43).…”

Traditional Chinese formula, lubricating gut pill, stimulates cAMP-dependent Cl− secretion across rat distal colonic mucosa

“…Disorders resulting in increased Cl − secretion, for example in bacterial or viral infections, are a primary cause of secretory diarrhea (Field, 2003). Whereas, decreased secretory function or increased fluid absorption in the colonic epithelium is typically associated with cystic fibrosis and constipation (Deachapunya et al, 2005;Bijvelds et al, 2009).…”