Insights into ways to treat diarrhoea

In the setting of diarrhoea, the colon often secretes substantial amounts of water, secondary chloride (Cl⁻) and/or potassium (K⁺). This ion secretion occurs via Cl⁻ (CFTR) and K⁺ (BK) channels, which are generally assumed to be co-located in the colonocyte apical membrane, although their exact cellular sites are not known. Linley and his co-workers have now identified the location of these channels in the colon epithelium. They found two types of crypt cells with regards to these ion channels with goblet cells having one particular type of channel (BK) and the other colonocytes expressing CFTR. Thus, in the colon, Cl⁻ secretion originates from colonocytes expressing apical CFTR, whereas K⁺ secretion is derived from a smaller population of goblet cells expressing apical BK channels. Their findings will help direct the development of anti-diarrheal drugs.⇓