Enterotoxigenic E. coli (ETEC) heat-stable toxin (ST) causes secretory diarrhea by increasing which intracellular second messenger in enterocytes?
- A cAMP
- B cGMP ✓
- C IP3
- D Calcium
Correct answer: B. cGMP
Explanation
ETEC heat-stable toxin binds to guanylate cyclase C on enterocytes, raising intracellular cGMP and causing secretory diarrhea. This mechanism is distinct from heat-labile toxin (LT) and cholera toxin, which activate adenylate cyclase and increase cAMP. Shiga toxin inhibits protein synthesis. The most tempting distractor is cAMP, but ST specifically acts via guanylate cyclase C.
Reference: Harrison's Principles of Internal Medicine, 20th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.