TNF and irritable bowel syndrome: As the effects of tenapanor on DRG hyperexcitability could be downstream of changes to intestinal permeability (10), we next probed the influence of tenapanor on intestinal barrier function under IBS-like conditions using primary human colon monolayer cultures treated with the proinflammatory cytokines TNF-α and IL-6, or fecal supernatants from patients with IBS-C and healthy controls.