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Role of Quercetin in Modulating Chloride Transport in the Intestine

View Article: PubMed Central - PubMed

ABSTRACT

Epithelial chloride channels provide the pathways for fluid secretion in the intestine. Cystic fibrosis transmembrane conductance regulator (CFTR) and calcium-activated chloride channels (CaCCs) are the main chloride channels in the luminal membrane of enterocytes. These transmembrane proteins play important roles in many physiological processes. In this study, we have identified a flavonoid quercetin as a modulator of CaCC chloride channel activity. Fluorescence quenching assay showed that quercetin activated Cl− transport in a dose-dependent manner, with EC50 ~37 μM. Short-circuit current analysis confirmed that quercetin activated CaCC-mediated Cl− currents in HT-29 cells that can be abolished by CaCCinh-A01. Ex vivo studies indicated that application of quercetin to mouse ileum and colon on serosal side resulted in activation of CFTR and CaCC-mediated Cl− currents. Notably, we found that quercetin exhibited inhibitory effect against ANO1 chloride channel activity in ANO1-expressing FRT cells and decreased mouse intestinal motility. Quercetin-stimulated short-circuit currents in mouse ileum was multi-component, which included elevation of Ca2+ concentration through L-type calcium channel and activation of basolateral NKCC, Na+/K+-ATPase, and K+ channels. In vivo studies further revealed that quercetin promoted fluid secretion in mouse ileum. The modulatory effect of quercetin on CaCC chloirde channels may therefore represent a potential therapeutic strategy for treating CaCC-related diseases like constipation, secretory diarrhea and hypertension. The inverse effects of quercetin on CaCCs provided evidence that ANO1 and intestinal epithelial CaCCs are different calcium-activated chloride channels.

No MeSH data available.


Inhibition of gastrointestinal movement by quercetin in mice. (A) Photographs of isolated mouse intestines showing traveled distance of activated charcoal after intraperitoneal administration of saline (negative control), Eact (50 μM), quercetin (200 μM) or quercetin (200 μM) plus Eact (50 μM). (B) Histogram comparing the peristaltic indexes from different treatments. Data are the means ± SEs from five experiments, *indicates the significant difference from control at the P < 0.05 level.
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Figure 9: Inhibition of gastrointestinal movement by quercetin in mice. (A) Photographs of isolated mouse intestines showing traveled distance of activated charcoal after intraperitoneal administration of saline (negative control), Eact (50 μM), quercetin (200 μM) or quercetin (200 μM) plus Eact (50 μM). (B) Histogram comparing the peristaltic indexes from different treatments. Data are the means ± SEs from five experiments, *indicates the significant difference from control at the P < 0.05 level.

Mentions: ANO1 is expressed in the interstitial cells of Cajal in the intestine where it modulates smooth muscle contraction (Huang et al., 2009; Hwang et al., 2009; Ferrera et al., 2010). Thus, intestinal motility measurement was performed in mice to evaluate the efficacy of quercetin in vivo. Intraperitoneal administration of 50 μM of the ANO1 activator Eact accelerated intestinal peristalsis, with peristaltic index of 72 ± 5.5% compared to saline control of 56 ± 6.9%. As shown in Figure 9A, quercetin (200 μM) significantly inhibited the basal and Eact-stimulated intestinal peristalsis. Figure 9B compares the peristaltic indexes from the different treatments. These results demonstrated that quercetin slowed intestinal peristalsis by inhibiting ANO1 activity.


Role of Quercetin in Modulating Chloride Transport in the Intestine
Inhibition of gastrointestinal movement by quercetin in mice. (A) Photographs of isolated mouse intestines showing traveled distance of activated charcoal after intraperitoneal administration of saline (negative control), Eact (50 μM), quercetin (200 μM) or quercetin (200 μM) plus Eact (50 μM). (B) Histogram comparing the peristaltic indexes from different treatments. Data are the means ± SEs from five experiments, *indicates the significant difference from control at the P < 0.05 level.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5120089&req=5

Figure 9: Inhibition of gastrointestinal movement by quercetin in mice. (A) Photographs of isolated mouse intestines showing traveled distance of activated charcoal after intraperitoneal administration of saline (negative control), Eact (50 μM), quercetin (200 μM) or quercetin (200 μM) plus Eact (50 μM). (B) Histogram comparing the peristaltic indexes from different treatments. Data are the means ± SEs from five experiments, *indicates the significant difference from control at the P < 0.05 level.
Mentions: ANO1 is expressed in the interstitial cells of Cajal in the intestine where it modulates smooth muscle contraction (Huang et al., 2009; Hwang et al., 2009; Ferrera et al., 2010). Thus, intestinal motility measurement was performed in mice to evaluate the efficacy of quercetin in vivo. Intraperitoneal administration of 50 μM of the ANO1 activator Eact accelerated intestinal peristalsis, with peristaltic index of 72 ± 5.5% compared to saline control of 56 ± 6.9%. As shown in Figure 9A, quercetin (200 μM) significantly inhibited the basal and Eact-stimulated intestinal peristalsis. Figure 9B compares the peristaltic indexes from the different treatments. These results demonstrated that quercetin slowed intestinal peristalsis by inhibiting ANO1 activity.

View Article: PubMed Central - PubMed

ABSTRACT

Epithelial chloride channels provide the pathways for fluid secretion in the intestine. Cystic fibrosis transmembrane conductance regulator (CFTR) and calcium-activated chloride channels (CaCCs) are the main chloride channels in the luminal membrane of enterocytes. These transmembrane proteins play important roles in many physiological processes. In this study, we have identified a flavonoid quercetin as a modulator of CaCC chloride channel activity. Fluorescence quenching assay showed that quercetin activated Cl&minus; transport in a dose-dependent manner, with EC50 ~37 &mu;M. Short-circuit current analysis confirmed that quercetin activated CaCC-mediated Cl&minus; currents in HT-29 cells that can be abolished by CaCCinh-A01. Ex vivo studies indicated that application of quercetin to mouse ileum and colon on serosal side resulted in activation of CFTR and CaCC-mediated Cl&minus; currents. Notably, we found that quercetin exhibited inhibitory effect against ANO1 chloride channel activity in ANO1-expressing FRT cells and decreased mouse intestinal motility. Quercetin-stimulated short-circuit currents in mouse ileum was multi-component, which included elevation of Ca2+ concentration through L-type calcium channel and activation of basolateral NKCC, Na+/K+-ATPase, and K+ channels. In vivo studies further revealed that quercetin promoted fluid secretion in mouse ileum. The modulatory effect of quercetin on CaCC chloirde channels may therefore represent a potential therapeutic strategy for treating CaCC-related diseases like constipation, secretory diarrhea and hypertension. The inverse effects of quercetin on CaCCs provided evidence that ANO1 and intestinal epithelial CaCCs are different calcium-activated chloride channels.

No MeSH data available.