Measurement of intraluminal pH changes in the gastrointestinal tract of mice with gastrointestinal diseases

As a fundamental and essential property, gastrointestinal (GI) tract pH reflects its condition and changes in several GI diseases such as inflammatory bowel disease (IBD), gastritis, etc. As a result, accurately measuring the GI pH is crucial for treatment, diagnosis, and prevention of GI diseases and contributes to developing GI disease models for basic studies. However, among pH measuring studies with animal models, there is no reliable method that can reflect the value and changing trends of GI pH in actual patients. In the current study, we developed a fast, simple method with pH indicator paper to measure the GI pH changes with GI content in normal mice and mice with colitis or hepatitis. Results demonstrated that normal mice's mean GI pH values were between 6.0 and 8.0, which was consistent with previous reports. Furthermore, the GI pH of colitis and hepatitis model mice showed the same pattern of lower values in the intestine and higher values in the stomach compared with normal mice. Our simple and timesaving method can accurately measure the dramatic changes in the GI pH of mice with GI diseases and is suitable for measuring the pH of sticky liquids with limited volume. Given all the merits listed above, this method is helpful for further research.