Stool pH measurement
Luminal stool pH was measured in Cftr +/+ andCftr -/- mice pre and 3 hours post gavage with Tenapanor. One to two fresh stool pellets were collected, placed in 50μl unbuffered distilled water and the pH determined with a pH-strip (Carl Roth, Karlsruhe, Germany). Following this, the pellets were homogenized and the pH was measured via a pre-calibrated TitraLab TIM 865 pH meter (Hach, Düsseldorf, Germany) with a Sension+ 5209 pH electrode (Hach, Düsseldorf, Germany).