Transepithelial SCFA fluxes link intracellular and extracellular pH regulation of mouse colonocytes

We have studied pH regulation in both intracellular and extracellular compartments of mouse colonic crypts, using distal colonic mucosa with intact epithelial architecture. In this work, we question how transepithelial SCFA gradients affect intracellular pH (pHi) and examine interactions between extracellular pH (pHo) and pHi regulation in crypts of distal colonic epithelium from mouse. We studied pH regulation in three adjacent compartments of distal colonic epithelium (crypt lumen, crypt epithelial cell cytosol, and lamina propria) with SNARF-1 (a pH sensitive fluorescent dye), digital imaging microscopy (for pHi), and confocal microscopy (for pHo). Combining results from the three compartments allows us to find how pHi and pHo are regulated and related under the influence of physiological transepithelial SCFA gradients, and develop a better understanding of pH regulation mechanisms in colonic crypts. Results suggest a complex interdependency between SCFA fluxes and pHo values, which can directly affect how strongly SCFAs acidify colonocytes.