Cermak R, Föllmer U, Wolffram S
Institute of Veterinary Physiology, University of Zurich, CH-8057 Zurich, Switzerland.
Am J Physiol. 1998 Nov;275(5):G1166-72. doi: 10.1152/ajpgi.1998.275.5.G1166.
The aim of this study was to investigate the possible effects of the flavonol quercetin, the most abundant dietary flavonoid, on the intestinal mucosa. In vitro experiments were performed with various segments of the rat intestine, using the Ussing chamber technique. Quercetin increased the short-circuit current (Isc) in the jejunum, ileum, and proximal and distal colon. Additional experiments were performed using preparations of the proximal colon. The maximum effective dose of quercetin was found to be approximately 100 microM. The quercetin-induced increase in Isc was inhibited by the Cl- channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoic acid. Adding blockers of the Na+-K+-2Cl- cotransporter to the serosal compartment diminished the increase of Isc due to quercetin. Ion substitution and flux measurements indicated that the effect of quercetin was due to electrogenic Cl- and HCO-3 secretion. In contrast to the aglycone, the quercetin glycoside rutin had no effect. The effect of quercetin on Isc was additive to the Isc increase induced by forskolin, but the flavonoid diminished the Isc evoked by carbachol. The phosphodiesterase inhibitor theophylline blocked the effect of quercetin. Genistein, a related isoflavone, did not alter the Isc evoked by quercetin. These findings demonstrate that the dietary flavonol quercetin induces Cl- secretion and most likely HCO-3 secretion in rat small and large intestine. The effects are restricted to the flavonol aglycone.
本研究的目的是调查膳食中最丰富的黄酮醇槲皮素对肠黏膜可能产生的影响。采用尤斯灌流小室技术，对大鼠肠道的不同节段进行了体外实验。槲皮素可增加空肠、回肠以及近端和远端结肠的短路电流（Isc）。使用近端结肠制剂进行了额外实验。发现槲皮素的最大有效剂量约为100微摩尔。Cl-通道阻滞剂5-硝基-2-（3-苯丙基氨基）苯甲酸可抑制槲皮素诱导的Isc增加。向浆膜腔室添加Na+-K+-2Cl-共转运体阻滞剂可减少槲皮素引起的Isc增加。离子置换和通量测量表明，槲皮素的作用是由于电生性Cl-和HCO-3分泌。与苷元不同，槲皮素糖苷芦丁没有作用。槲皮素对Isc的作用与福斯可林诱导的Isc增加具有相加性，但该黄酮类化合物可减少卡巴胆碱诱发的Isc。磷酸二酯酶抑制剂茶碱可阻断槲皮素的作用。相关异黄酮染料木黄酮不会改变槲皮素诱发的Isc。这些发现表明，膳食黄酮醇槲皮素可诱导大鼠小肠和大肠中的Cl-分泌，很可能还有HCO-3分泌。其作用仅限于黄酮醇苷元。
