Cephalopod ink/secretion from the blue-ringed octopus (Hapalochlaena) is lethal because of which toxin, also found in certain pufferfish?
- A Tetrodotoxin — sodium channel blocker causing flaccid paralysis ✓
- B Conotoxin — calcium channel blocker
- C Saxitoxin — potassium channel opener causing depolarisation
- D Palytoxin — Na+/K+-ATPase inhibitor causing massive cell depolarisation
Correct answer: A. Tetrodotoxin — sodium channel blocker causing flaccid paralysis
Explanation
The blue-ringed octopus produces tetrodotoxin (TTX) in its salivary glands via symbiotic bacteria. TTX binds with high affinity to the outer vestibule of voltage-gated sodium channels (Nav1.4, Nav1.6, Nav1.7) and blocks sodium influx, preventing action potential generation in peripheral nerves and diaphragmatic muscle. The result is ascending flaccid paralysis and respiratory failure with preserved consciousness — a terrifying clinical picture. Pufferfish (fugu) toxicity is identical. There is no antidote; treatment is supportive ventilation.
Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.