Increased Cl secretion is a mechanism associated with which toxin?

Increased chloride secretion is primarily associated with Vibrio cholera toxin. This toxin works by inhibiting the adenylate cyclase activity in intestinal epithelial cells, leading to an increase in intracellular cAMP levels. Elevated cAMP stimulates the cystic fibrosis transmembrane conductance regulator (CFTR) protein, which enhances chloride ion transport across the intestinal epithelium into the intestinal lumen. This results in increased secretion of chloride ions, which also drives water out of the cells into the lumen, resulting in the characteristic watery diarrhea seen in cholera infection.

In contrast, other mentioned toxins do not primarily function through this chloride secretion mechanism. For instance, Staphylococcal enterotoxin causes food poisoning by stimulating the vomiting center but does not directly increase chloride secretion. Botulinum toxin acts on nerves to inhibit acetylcholine release, causing paralysis rather than gastrointestinal fluid secretion. Clostridium perfringens toxin can lead to enterotoxemia but operates through different mechanisms and is not directly involved in the increased secretion of chloride like Vibrio cholera toxin. This specificity of action helps to accurately associate Vibrio cholera toxin with elevated chloride secretion in the gut.