Slowed gastric emptying and improved oral glucose tolerance produced by a nanomolar‐potency inhibitor of calcium‐activated chloride channel TMEM16A

Abstract

Interstitial cells of Cajal, which express the calcium‐activated chloride channel transmembrane member 16A (TMEM16A), are an important determinant of gastrointestinal (GI) motility. We previously identified the acylaminocycloalkylthiophene class of TMEM16A inhibitors, which, following medicinal chemistry, gave analog 2‐bromodifluoroacetylamino‐5,6,7,8‐tetrahydro‐4H‐cyclohepta[b]thiophene‐3‐carboxylic acid o‐tolylamide (TMinh‐23) with 30 nM half‐maximal inhibitory concentration. Here, we tested the efficacy of TMinh‐23 for inhibition of GI motility in mice. In isolated murine gastric antrum, TMinh‐23 strongly inhibited spontaneous and carbachol‐stimulated rhythmic contractions. Pharmacokinetic analysis showed predicted therapeutic concentrations of TMinh‐23 for at least 4 h following a single oral or intraperitoneal dose at 10 mg/kg. Gastric emptying, as assessed following an oral bolus of phenol red or independently by [99mTc]‐diethylenetriamine pentaacetic acid scintigraphy, was reduced by TMinh‐23 by ∼60% at 20 min. Interestingly, there was little effect of TMinh‐23 on baseline whole‐gut transit time or time to diarrhea induced by castor oil. Consequent to the delay in gastric emptying, TMinh‐23 administration significantly reduced the elevation in blood sugar in mice following an oral but not intraperitoneal glucose load. These results provide pharmacological evidence for involvement of TMEM16A in gastric emptying and suggest the utility of TMEM16A inhibition in disorders of accelerated gastric emptying, such as dumping syndrome, and potentially for improving glucose tolerance in diabetes mellitus/metabolic syndrome and enhancing satiety in obesity.—Cil, O., Anderson, M. O., Yen, R., Kelleher, B., Huynh, T. L., Seo, Y., Nilsen, S. P., Turner, J. R., Verkman, A. S. Slowed gastric emptying and improved oral glucose tolerance produced by a nanomolar‐potency inhibitor of calcium‐activated chloride channel TMEM16A. FASEB J. 33, 11247–11257 (2019). http://www.fasebj.org

Genome-wide Analysis Identifies Novel Gallstone-susceptibility Loci Including Genes Regulating Gastrointestinal Motility

“…ANO1 (also known as TMEM16A ) is a calcium-activated chloride channel widely expressed in the gastrointestinal tract with roles in automaticity and contraction of the smooth muscle cells via the interstitial cells of Cajal 33 . Administration of ANO1 inhibitors (TMinh-23) in murine models impedes gastric emptying with improved oral but not parenteral glucose tolerance supporting the role of ANO1 as a gastric motility promoter 33,34 . ANO1 is also expressed in the biliary epithelium where it has another role in secretion of fluid from the apical cholangiocyte membrane in response to bile acids suggesting it may promote increased bile flow 35 .…”

SLC26A6-selective inhibitor identified in a small-molecule screen blocks fluid absorption in small intestine

“…Clonal FRT cell lines were generated by limited dilution, examined by fluorescence microscopy to confirm mCherry and YFP expression, and functionally characterized to confirm slc26a6 activity to generate the cell line FRT-YFP-slc26a6. FRT cell lines coexpressing YFP and slc26a3, slc26a4, SLC26A9, or TMEM16A were previously described ( 7 , 11 , 28 ). FRT cells were cultured with Kaign’s modified Ham’s F12 medium supplemented containing 10% FBS, 2 mM L-glutamine, 100 U/ml penicillin, 100 μg/ml streptomycin, 18 μg/ml myo-inositol, and 45 μg/ml ascorbic acid, with appropriate selection antibiotics.…”

“…Niflumic acid was used as a positive control for SLC26A isoforms ( 7 ). For TMEM16A, the selective small-molecule inhibitor TM inh -23 was used as a positive control ( 28 ). The activities of ENaC, CFTR, and CaCC were determined using well-differentiated HBE cells as described previously ( 13 ).…”

A small molecule inhibitor of the chloride channel TMEM16A blocks vascular smooth muscle contraction and lowers blood pressure in spontaneously hypertensive rats

“…Our group recently identified, and optimized by medicinal chemistry, TMEM16A inhibitor TM inh -23 (Figure 1a), which showed nanomolar potency and good selectivity and pharmacologic properties. 15,16 Herein, we investigated its efficacy in blocking vascular smooth muscle contraction in vitro and reducing BP in a rat model of hypertension.…”