A 20-year-old woman is visiting Liberia. Two weeks into her trip, she develops painless diarrhea consisting of extremely watery stools. Upon seeking medical help, she is informed that there has been an epidemic of this infectious disease. She is treated with high volumes of oral rehydration fluid. The mechanism by which this diarrhea occurs involves a defect in the function of which ion transport?
- Sodium.
- Potassium.
- Calcium.
- Chloride.
- Phosphate.
The woman suffers from cholera. Vibrio cholerae secretes cholera toxin, which by way of increased cAMP activates the cystic fibrosis transmembrane conductance regulator (CFTR), resulting in hypersecretion of chloride into the small intestine. This, in turn, results in an influx of cations and water to balance the electrochemical and osmotic gradients.
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